ProSoundWeb Community

Sound Reinforcement - Forums for Live Sound Professionals - Your Displayed Name Must Be Your Real Full Name To Post In The Live Sound Forums => AC Power and Grounding => Topic started by: Frank DeWitt on September 08, 2014, 01:22:23 PM

Title: No Box, Safe?
Post by: Frank DeWitt on September 08, 2014, 01:22:23 PM
Sometimes we decide something is safe because of the physics involved.  Sometimes we think it is safe because that is the way we do it.   I have found home wiring from the late 1800s and early 1900s that did not use any boxes.  Seems wrong.

Then I found this.
Is it safe?

(http://lot271.files.wordpress.com/2011/06/img_2519.jpg)

http://www.electrical-contractor.net/forums/ubbthreads.php/topics/213916/1.html (http://www.electrical-contractor.net/forums/ubbthreads.php/topics/213916/1.html)
Title: Re: No Box, Safe?
Post by: Stephen Swaffer on September 08, 2014, 02:00:56 PM
Code only allows mounting brackets like that for low voltage/power limited circuits over here.  Also lack of staples securing the wire is unsafe.  I have heard of people being injured because a toggle bolt tightened up on a piece of unsecured romex and became energized-the incident I heard of happened with a bathroom towel bar - obviously not a good place for that to happen!

I am sure a lot of people get away with doing it that way-for a while.
Title: Re: No Box, Safe?
Post by: Frank DeWitt on September 08, 2014, 02:09:15 PM
I am sure a lot of people get away with doing it that way-for a while.

It is not code in the US but a lot of people have been getting away with it for a long time in Australia where this picture was taken.
Title: Re: No Box, Safe?
Post by: Mike Sokol on September 08, 2014, 06:58:09 PM
Sometimes we decide something is safe because of the physics involved.  Sometimes we think it is safe because that is the way we do it.   I have found home wiring from the late 1800s and early 1900s that did not use any boxes.  Seems wrong.

Then I found this.
Is it safe?


One of the functions of the "j-box" is to contain any sparks from loose wiring connections (such as wire nuts). Without a non-flammable box to contain them, those sparks could easily ignite flammable materials in the walls. And an electrical fire inside of a wall is very bad.

One of the reasons that old K&T wiring didn't catch fire as often as you might imagine may be that those were soldered connections. While wire nuts are certainly safe if properly installed, I would consider a properly soldered and taped connection to be far superior to a wire nut connection, at least as far as spark potential.

Now, I'm not advocating a return to the days of molten solder pots held over your head while standing on a ladder. But wire nuts and modern screw-connected receptacles are not designed to be mounted next to flammable material. They both need to be in non-flammable boxes.   
Title: Re: No Box, Safe?
Post by: Jonathan Johnson on September 08, 2014, 07:35:39 PM
Upon seeing this, but before clicking in the link to the forum where this picture came from, I quickly recognized this as being from somewhere outside of the United States. My second thought was that maybe the electrical devices (switches, receptacles) that were to be installed included surface mount boxes which would contain the connections.

Then I clicked the link and learned the truth. Oh, my.
Title: Re: No Box, Safe?
Post by: TJ (Tom) Cornish on September 08, 2014, 09:04:33 PM
Sometimes we decide something is safe because of the physics involved.  Sometimes we think it is safe because that is the way we do it.   I have found home wiring from the late 1800s and early 1900s that did not use any boxes.  Seems wrong.

Then I found this.
Is it safe?
Safe is relative.  Presumably someone has done statistical analysis to understand the ramifications of various building practices, though like government, building codes tend to meander over time.
Title: Re: No Box, Safe?
Post by: Stephen Swaffer on September 08, 2014, 10:34:27 PM
I should have taken another picture.  Saturday I rewired a fan on a grain bin.  Old wiring = 8-3 indoor romex, line end supported by terminal screws on breaker in an outdoor panel with the cover open, ran about 50 feet, mid way was a splice (no box-result of being run over with a mower), load end ran though a piece of flex, but no strain relief.  Been that way for a couple of years, and no one got hurt.  With this as your sample group, statistically it was safe (even with the hole in front of the open panel that made you lose your balance and fall towards the open panel.)  I'm guessing no insurance company would want to cover the install though.

Tom is right though-safe can never be an absolute-it is really about minimizing risk, or at least getting it to an acceptable level which varies depending on your standard.

Mike has advocated using the NEC as the standard here.  By that standard the OP is not safe.
Title: Re: No Box, Safe?
Post by: Frank DeWitt on September 08, 2014, 11:17:03 PM

Mike has advocated using the NEC as the standard here.  By that standard the OP is not safe.

But by Second Edition AS/ACIF S009:2006. It is safe.  I don't think it is.  I would prefer boxes. But codes are local.  If I had a trained professional build a house in Australia there would be no boxes.  Btw I understand that wires are terminated differently and wire nuts are not used. 

Please understand that I am not advocating not using boxes.  I am just pointing out that codes may or may not be enough.  We actually need to think through what is safe and why.  Mike points out that a box will contain sparks and help prevent fires in walls.  A good point and I agree with it.

In another thread I said that our church goes beyond code with electrical safety in our Baptismal.  We did that because we thought it through and decided that NEC was not enough. 

Understanding the why as this forum keeps teaching us is better then only knowing the code.
Title: Re: No Box, Safe?
Post by: Steve M Smith on September 09, 2014, 02:53:37 AM
We don't use wire nuts in the UK.  They looked positively scary the first time I saw one!

Mike points out that a box will contain sparks and help prevent fires in walls.  A good point and I agree with it.
Although it would be better not to have any sparks to contain!


Steve.
Title: Re: No Box, Safe?
Post by: Jeff Bankston on September 09, 2014, 05:10:36 AM
We don't use wire nuts in the UK.  They looked positively scary the first time I saw one!
Although it would be better not to have any sparks to contain!


Steve.
wire nuts are awsome ! i use Ideal brand wing nuts. uh oh i just told everyone i'm a wing nut job !
Title: Re: No Box, Safe?
Post by: Steve M Smith on September 09, 2014, 06:15:06 AM
uh oh i just told everyone i'm a wing nut job !

We already knew - we could tell by your profile picture!


Steve.
Title: Re: No Box, Safe?
Post by: TJ (Tom) Cornish on September 09, 2014, 07:31:37 AM
But by Second Edition AS/ACIF S009:2006. It is safe.  I don't think it is.  I would prefer boxes. But codes are local.  If I had a trained professional build a house in Australia there would be no boxes.  Btw I understand that wires are terminated differently and wire nuts are not used.
I don't disagree with you about preferring boxes, but being the devil's advocate for a moment, why do we allow Romex?  Surely requiring MC/BX or conduit and metal boxes would be safer?  Why is it legal to use $0.19 receptacles and switches that are so poor quality that they fail within a couple years and get loose or arc?
Title: Re: No Box, Safe?
Post by: Stephen Swaffer on September 09, 2014, 08:20:30 AM

In another thread I said that our church goes beyond code with electrical safety in our Baptismal.  We did that because we thought it through and decided that NEC was not enough. 

Understanding the why as this forum keeps teaching us is better then only knowing the code.

One of the inspectors I frequently work with, has pointed out that he often sees substandard work (at least in his eyes).  Legally he can only mandate code (that is the law in his jurisdiction), so he can't insist on changes.  IMO, code is your starting point-a lot of time has gone into coming to a consensus on safety (I know politics and money influences it, too).-and often by people who have more knowledge or data in a given area than most of us do.

Why not wire everything with explosion proof fittings, or rigid conduit like they used to do?  Wire ampacities are based on a certain ultimate temperature of the wire-if you load a wire to its 90 deg C ampacity it will run at 90 deg C and most people touching a wire that is that warm would be alarmed.  (It is almost never acceptable to run at the 90 deg ampacity anyway, but that is another discussion) Why not adjust the tables and insist we run cooler?

For that matter cables and trip hazards, as discussed.  Why not just trench them in every time?  Concrete floor you say?  They make jack hammers...

Obviously being facetious-but making the point it always comes down to cost/practicality vs safety-and statistics.  But that is where codes have to stop short at times.  I think it is better to require an attainable level of safety-if you set the bar too high and people can't get there, then they tend to throw caution out the window and just do whatever.
Title: Re: No Box, Safe?
Post by: Steve M Smith on September 09, 2014, 08:23:06 AM
I don't know if it appears in American laws, rules or codes, but in UK legislation, the words 'as far as is reasonably practical' appear quite a lot.


Steve.
Title: Re: No Box, Safe?
Post by: Frank DeWitt on September 09, 2014, 09:14:35 AM
We don't use wire nuts in the UK.  They looked positively scary the first time I saw one!
Although it would be better not to have any sparks to contain!
Steve.

Interesting. I can see why they would look scary.  If we did the same thing inside a product it would be called a flying splice or haywired  In a product every splice should be in a terminal or terminal strip.

Steve.  Help us out.  What do you use instead of wire nuts?  Are there extra terminals on switches and lamp fixtures for wires that are passing through?   I found reference on the internet to a ceiling "rose" with terminals but it was called the old way.

Thanks in advance.
Title: Re: No Box, Safe?
Post by: Steve M Smith on September 09, 2014, 09:48:00 AM
Steve.  Help us out.  What do you use instead of wire nuts?  Are there extra terminals on switches and lamp fixtures for wires that are passing through?
Junction boxes and ceiling roses:
http://www.speedyelectrical.co.uk/1.aspx?NSearchMode=SINGLE&NSearchStr=5374&gclid=CNukrb-i1MACFagfwwodkXUAYA (http://www.speedyelectrical.co.uk/1.aspx?NSearchMode=SINGLE&NSearchStr=5374&gclid=CNukrb-i1MACFagfwwodkXUAYA)
http://uk.farnell.com/productimages/farnell/standard/42267559.jpg (http://uk.farnell.com/productimages/farnell/standard/42267559.jpg)
Wired like this: http://www.davesdiytips.com/wp-content/uploads/2009/01/daves-ceiling-rose.jpg (http://www.davesdiytips.com/wp-content/uploads/2009/01/daves-ceiling-rose.jpg)
 
Steve.
 
 
Title: Re: No Box, Safe?
Post by: Jonathan Johnson on September 09, 2014, 12:37:34 PM
We don't use wire nuts in the UK.  They looked positively scary the first time I saw one!

Prior to the invention of wire nuts, the proper method of connecting wires was to twist them together and solder them, then wrap them in vulcanized rubber tape, followed by friction tape (an asphalt impregnated fabric tape). This is a superior method to a wire nut, but it is extremely time-consuming in comparison, and does not make for easy modifications (adding a connection) in the future.

The problem is that most homeowners did not solder the connections, but only twisted the wires together and taped them. This often resulted in a weak connection, and when the circuit is loaded near the ampacity of the wire, the connections would heat up, arc, and cause fires. Prior to the invention of PVC electrical tape (aka "black tape"), homeowners also skipped the rubber tape, wrapping the unsoldered connection only in friction tape.

There was an interim connection method -- still used for EGC (grouding) wires -- of using a crimp ring, then taping the crimped connection.

I believe the invention of the wire nut, and it's subsequent acceptance by codes and AHJ, was spurred by the improper use of "twist and tape" connections. At the very least, a properly installed wire nut is far superior to an unsoldered "twist and tape" connection. One of the problems with wire nuts is that it's easy for a wire to not be gripped tightly when installing the nut, resulting an an equally hazardous loose connection. That's why after installing a wire nut, I tug on EACH wire individually to make sure they are secure.

There is debate about whether or not you should pretwist the wire ends together before installing the wire nuts. Many manufacturers indicate it's not necessary. Twisting may help prevent a wire slipping out during installation, but twisting could also prevent the conductors from making good contact with each other because the wire nut might not be able to "crimp" them together. Personally, I don't pretwist; I ensure the integrity of the connection by tugging as previously described. More debate: http://www.mikeholt.com/forum/Forum1/HTML/005609.html
Title: Re: No Box, Safe?
Post by: Steve M Smith on September 09, 2014, 01:01:23 PM
The problem is that most homeowners did not solder the connections, but only twisted the wires together and taped them.

When I moved into my previous house, I wondered why the power to the shed used to trip out all the time.  When I investigated it, I found the cable running from the house to the shed was ordinary cable intended for internal use.  It was also made up of two pieces which had been joined by twisting the solid (not stranded) conductors together and taping them... this was buried in the ground!!

Do wire nuts require stranded cable?  I can't see them working with our solid conductors.


Steve.
Title: Re: No Box, Safe?
Post by: Art Welter on September 09, 2014, 01:54:42 PM
Do wire nuts require stranded cable? 
No, they are used both with solid single conductor and stranded. In the case of wiring lighting fixtures, a wire nut may join both types of wire.


Title: Re: No Box, Safe?
Post by: Frank Koenig on September 09, 2014, 02:26:50 PM
I hate wire nuts. They're ugly. But they are the customary way of splicing small building wire in the United States, so I have made peace with them in the following way:

Choose a manufacturer whose wire nuts work. Some don't. I've had good luck with the ones from 3M.

Use the right size nut for the total cross-sectional area of the splice. When in doubt, try it, and change it if needed.

Ensure that the ends of all the wires line up perfectly. One way of doing this is to strip the wires a little long, line up the insulation, and then trim the wires all together to the proper length with a flush cutter. Watch where the schnibbles go.

When splicing solid wire, such as 12 AWG THHN, do not twist. Hold the wires very tightly to preserve the alignment and make sure the nut has achieved a good bite into all the wires before cranking it down hard. Stop when more torque would start to twist the wires outside the nut.

When splicing a stranded wire to solid wire (16 AWG fixture wire to 12 AWG solid, for example) lightly twist and flatten the stranded against the larger solid wire and then gingerly start the nut so as not to push the stranded wire down.

And, of course, when done give each wire a good, hard wiggle and pull relative to the nut, to ensure that it's tight.

Whenever given the choice I use stranded wire and high quality (nylon insulated) crimp-on lugs and wire stuff like and airplane, not a house.
Title: Re: No Box, Safe?
Post by: Steve M Smith on September 09, 2014, 03:16:19 PM
If we did the same thing inside a product it would be called a flying splice or haywired  In a product every splice should be in a terminal or terminal strip.

Strangely, the only place I have seen wire nuts in this country is inside a product.

I recently fitted a bathroom mirror with lights which had wire nuts inside. 


Steve.
Title: Re: No Box, Safe?
Post by: Art Welter on September 09, 2014, 03:27:35 PM
Choose a manufacturer whose wire nuts work. Some don't. I've had good luck with the ones from 3M.
Unfortunately, it seems we often find out which wire nuts don't work well when we open up a box and see plastic bits of the wire nuts laying on the bottom, or expanded helical coil wire nut inserts no longer making connection, or bi-metalic corrosion from the dissimilarity of the coil and wire material.

Title: Re: No Box, Safe?
Post by: TJ (Tom) Cornish on September 09, 2014, 03:43:04 PM
Choose a manufacturer whose wire nuts work. Some don't. I've had good luck with the ones from 3M.
Coming from the land of 3M this is a bit hard for me to say, but either I had an entire bag of nuts from a defective run, or 3M nuts suck.  I had tons of problems with the nut just spinning on the wires.  Maybe that's intentional and I'm stupid, but I don't think so.  I've used Ideal nuts for years with great results. 
Title: Re: No Box, Safe?
Post by: Jeff Bankston on September 09, 2014, 04:51:02 PM
3m scotch locks are the worst wire nuts i'v ever seen. even then the improved ones are junk. i never allowed them on my jobs. if the supply house my boss used only had scotch i would tell him to call another supply house and get Ideal or GB wing nuts. a man needs to know how to tighten his nuts and keep the junk nuts out of his trunk.
Title: Re: No Box, Safe?
Post by: Art Welter on September 09, 2014, 05:35:53 PM
Coming from the land of 3M this is a bit hard for me to say, but either I had an entire bag of nuts from a defective run, or 3M nuts suck.  I had tons of problems with the nut just spinning on the wires.  Maybe that's intentional and I'm stupid, but I don't think so.  I've used Ideal nuts for years with great results.
Also coming from the Land of 10,000 Nuts, and having worked in a plastics factory there, saw many examples of parts that were failure prone from too rapid heat/cold cycling in manufacture, and parts with metal inserts were especially problematic. There is a fine line between good parts/too slow, and more parts per hour that will fail.

As simple as a wire nut seem on the surface, there a lot of things to go wrong, and when they do there may be batches of them.
Title: Re: No Box, Safe?
Post by: Mike Sokol on September 11, 2014, 04:34:49 PM
As simple as a wire nut seem on the surface, there a lot of things to go wrong, and when they do there may be batches of them.

I've been helping a No~Shock~Zone reader chase down the reason for his RV hot-skin voltage, and looks like the culprit was a wire-nut connecting solid and stranded wires for the chassis ground. See below. I personally don't think wire nuts should be used in moving vehicles such as RV trailers since the vibration from bouncing down the road is a sure way to loosen up things in a hurry.

Mike - I think I found it!  The pigtail in the junction box between the Franks Autotransformer and the Power center bare wire had come loose from the wire nut.  Since it was wrapped with black tape it looked secure but was not.

Since it was “inside” the Franks “power tester” the incoming ground was solid but the ground to the power center was not. Tomorrow I will solder those three connections and wrap with Splicing tape. Hopefully this will solve my hot skin issue.
Lou
Title: Re: No Box, Safe?
Post by: Stephen Swaffer on September 11, 2014, 06:09:04 PM
Properly sized and applied wire nuts don't need tape-taped wired nuts are often a sign of someone using the wrong size/defective or poor quality nwire nut.  I would guess in manufacturing low price wins-so perhaps an inferior design.  Also, tape is sometimes used to "weatherprooof" a connection-tape alone does not work well and especially on wire nuts because their is a void to hold moisture, where as a connection that dries quickly would be less liekly to corrode. 

I have used wire nuts in a pinch in vehicles and they work fine-spring tension is usually a plus in high vibration applications. 

Someone mentioned using crimp connectors earlier in the thread-though the exact application was not clear.  I have had inspectors point out that the terminals on devices (switches/receptacles) are UL listed for connection with either solid or stranded wire-but not necessarily with terminals.  But I do not take sides on that issue and plead the 5th as far as code violations in that area.

There are no perfect or ideal (small "i") wire connectors-they all have pros and cons.  IMO, connections are one area that workmanship is critical-whether it is a solder/mechanical/compression/exothermic weld-taking the care to make a secure connection is the mark of a craftsman.
Title: Re: No Box, Safe?
Post by: Jay Barracato on September 11, 2014, 06:38:39 PM
The key to wire nuts is the twist in the wire before they are applied.

Sent from my DROID RAZR HD using Tapatalk

Title: Re: No Box, Safe?
Post by: frank kayser on September 11, 2014, 08:09:16 PM
The key to wire nuts is the twist in the wire before they are applied.

Sent from my DROID RAZR HD using Tapatalk


Evident from a number of the above posts, not everyone believes in pre-twisting the wires before applying wire nuts.
And the wire-nut manufacturers are not sharing their feelings on their preferred practices.


I do know that if the copper is nicked during insulation removal, that can be a stress riser and a point for possible breakage in the future.
I've seen those pieces left inside a wire nut...


frank
Title: Re: No Box, Safe?
Post by: Jeff Bankston on September 11, 2014, 11:12:31 PM
i'm a commercial electrician. i have twisted on tens of thousands of wire nuts. i dont care about nor do i reconize some pole as being valid. Ideal instructions say not to pre twist the wires together. Ideal specifies that you hold the wires together , put the wire nut on and then twist. properly installed wire nuts will automatically twist the wires together. properly installed wire nuts will not fall off. tape on the bottom of wire nuts is never required but it will not cause a problem either. some companies , and general contractors want tape around the wire nuts. electrical inspectors dont have a problem with tape. the srping inside the wire nut cuts grooves in the wire and works like a screw when properly installed. those that dont know what they are doing are the ones that make bad connections. corroded connections are the result of wires being exposed to moisture and those connection shouild be in a "Bell Box" with silicone sealed seams. in the 70's when i first worked as a helper all the electricians hed a small propane torch,solder, and friction tape. as wire nuts came on the scene solder joints went away. i have done work in buildings with 30 yo wire nut connection that were very tight. i have seen screw lugs that loosedned up and melted down. i had wire nuts in my 66 ford wagon for 75,000 miles and were as tight as the day i installed them. as i said above , i have worked as a commercial electrician for over 20 years and these are the facts.
Title: Re: No Box, Safe?
Post by: Jeff Bankston on September 11, 2014, 11:16:57 PM
The key to wire nuts is the twist in the wire before they are applied.

Sent from my DROID RAZR HD using Tapatalk
this is your opinion and is null and void. and thats a big problem. people giving advice that dont know what they are talking about. i have ben a commercial electrician for over 20 years and i say > read the directions that come with the wire nuts. maybe you do and maybe you dont according to the manufactuer. when you work as an electrician you know what works and unless your an electrician you really dont know.
Title: Re: No Box, Safe?
Post by: Mike Sokol on September 12, 2014, 12:22:36 AM
this is your opinion and is null and void. and thats a big problem. people giving advice that dont know what they are talking about. i have ben a commercial electrician for over 20 years and i say > read the directions that come with the wire nuts. maybe you do and maybe you dont according to the manufactuer. when you work as an electrician you know what works and unless your an electrician you really dont know.

Jeff,

This is just a friendly discussion and poll. Please calm down and don't get your (wire)nuts in a twist.  ;D



Title: Re: No Box, Safe?
Post by: Jay Barracato on September 12, 2014, 05:35:56 AM
this is your opinion and is null and void. and thats a big problem. people giving advice that dont know what they are talking about. i have ben a commercial electrician for over 20 years and i say > read the directions that come with the wire nuts. maybe you do and maybe you dont according to the manufactuer. when you work as an electrician you know what works and unless your an electrician you really dont know.

I agree with the "read the directions", apparently the way I was taught has changed. The box of nuts i have sitting on the bench says "pretwisting is unnecessary". Of course that also tells me the practice must be fairly common or they wouldn't have bothered.

So my question is: is installing the nut supposed to twist the wires (I have removed many with no mechanical bond between the wires) or if the wires are not twisted what creates the mechanical bond?

Sent from my DROID RAZR HD using Tapatalk

Title: Re: No Box, Safe?
Post by: Jeff Bankston on September 12, 2014, 05:52:09 AM
I agree with the "read the directions", apparently the way I was taught has changed. The box of nuts i have sitting on the bench says "pretwisting is unnecessary". Of course that also tells me the practice must be fairly common or they wouldn't have bothered.

So my question is: is installing the nut supposed to twist the wires (I have removed many with no mechanical bond between the wires) or if the wires are not twisted what creates the mechanical bond?

Sent from my DROID RAZR HD using Tapatalk
when they are installed per directions the wires twist inside the wire nut. when you remove a nut the wires are suppose to stay twisted together. you use your side cutters to untwist the wires.
Title: Re: No Box, Safe?
Post by: Jay Barracato on September 12, 2014, 06:19:44 AM
The ones I have do not twist the wires in the nut. When you undo the nut they are still loose. If you use a nut driver it will twist the wire below the nut not in the nut.

The best I could do cranking down by hand put a 1/2 turn on the exposed copper for about 4 turns on the insulation below the nut.

A quick peek on mike Holt's forum shows many licensed electricians whose practice matches the way I was taught.

Sent from my DROID RAZR HD using Tapatalk
Title: Re: No Box, Safe?
Post by: Frank DeWitt on September 12, 2014, 09:09:03 AM
I worked for 10 years as a field service tech for a fire alarm company.  Fire alarms run a small current through every wire connected to the panel to "supervise" the wiring.  A wire comes lose or breaks or a external device fails and you get a trouble alarm. 

I spent a very long day working with a hospital maintenance guy looking for a open wire in a system that had been in place and working for years.  We finally tracked it down to a large junction box mounted on the wall in the hall.  We knew there was signal going in and nothing coming out.  Inside the box was about 50 wire nuts  (This was about a 18 in sq box carrying fire alarm signals so it was not over filled.)  Using telephone test probes with a sharp pin built into them I tracked the signal down to a spot 2 in from a wire nut.  2 in away on the other wire there was no signal.  With an audience and great fan fair I took off the wire nut expecting to reveal some hack work.  We found two wires neatly stripped twisted together and cut flush with one another.

They looked good.  They looked like they would carry power.  in fact I am convinced that if they had had 120 VAC with some current they would have arced and then worked.

I squeezed them with lineman's pliers and they system worked.  We cut a inch off the ends of the two wires, stripped them, put on a new wire nut and walked away shaking our heads.

If it is built by man it will fail.

BTW to the commercial electricians on the list, Thank You.  More then a few times we would need a new wire to fix something in a big old building like a hospital.  We would open a pull box and there laying on the bottom of the box was the end of a spare someone had pulled.  Big Grin.
Title: Re: No Box, Safe?
Post by: Stephen Swaffer on September 12, 2014, 10:03:47 AM

This is just a friendly discussion and poll.

One of the values of this forum is the opportunity to get input from people with various experiences.  Some on here work primarily in commercial/industrial environments that are tightly controlled by unions/inspectors etc, others work mainly with temp power (and have taught me things I overlooked in code), etc.  I work in a rural area with a mix of resi/ag/industrial and tighter inspection requirements in some areas than others.

My comments on wire nuts were the result of an informal fat thumb "poll" from observations-many times from nonprofessionals.  I do a LOT of work on agricultural wiring-I am lucky to find a 3R (rain tight) rather than a NEMA 1 indoor box.  It would be ludicrous to expect every box exposed to moisture to be silcone sealed-but when I am in a commercial/industrial environment doing so "feels" right.

Usually in commercial/industrial I like to use stranded wire-and when using stranded wire often it seems the wire nuts do a fine job of twisting the wires together.  Residential is almost always solid wire-NM/romex.  Personally, I find that twisting the wires together prior to aplying the wire nut appears to make a more secure connection.  As with so many things, IMO the answer is "it depends." I have a friend that ALWAYS twists wires together and always uses a pair of linesman pliers to finish tightening the nut.  Sometimes I learn tricks and tips from him and sometimes he learns from me-in the end we both get better at what we do form the interaction.
Title: Re: No Box, Safe?
Post by: Mike Sokol on September 12, 2014, 10:33:27 AM
One of the values of this forum is the opportunity to get input from people with various experiences. 

It's pretty interesting just how emotional this forum gets about apparently simple things such as wire nuts. But it's the simple things that can cause the most damage.

For want of a nail the shoe was lost.
For want of a shoe the horse was lost.
For want of a horse the rider was lost.
For want of a rider the message was lost.
For want of a message the battle was lost.
For want of a battle the kingdom was lost.
And all for the want of a horseshoe nail.

Title: Re: No Box, Safe?
Post by: Scott Holtzman on September 12, 2014, 12:52:33 PM
I worked for 10 years as a field service tech for a fire alarm company.  Fire alarms run a small current through every wire connected to the panel to "supervise" the wiring.  A wire comes lose or breaks or a external device fails and you get a trouble alarm. 

I spent a very long day working with a hospital maintenance guy looking for a open wire in a system that had been in place and working for years.  We finally tracked it down to a large junction box mounted on the wall in the hall.  We knew there was signal going in and nothing coming out.  Inside the box was about 50 wire nuts  (This was about a 18 in sq box carrying fire alarm signals so it was not over filled.)  Using telephone test probes with a sharp pin built into them I tracked the signal down to a spot 2 in from a wire nut.  2 in away on the other wire there was no signal.  With an audience and great fan fair I took off the wire nut expecting to reveal some hack work.  We found two wires neatly stripped twisted together and cut flush with one another.

They looked good.  They looked like they would carry power.  in fact I am convinced that if they had had 120 VAC with some current they would have arced and then worked.

I squeezed them with lineman's pliers and they system worked.  We cut a inch off the ends of the two wires, stripped them, put on a new wire nut and walked away shaking our heads.

If it is built by man it will fail.

BTW to the commercial electricians on the list, Thank You.  More then a few times we would need a new wire to fix something in a big old building like a hospital.  We would open a pull box and there laying on the bottom of the box was the end of a spare someone had pulled.  Big Grin.

I called these highly resistive connections.  A high impedance Ohm Meter would show good but apply any current and they would block down.


Interesting, the folks and bell labs came up with the concept of sealing current.  A brief pulse sent down the telephone line to clear dirty connections. 

Title: Re: No Box, Safe?
Post by: Jonathan Johnson on September 12, 2014, 01:51:39 PM
There is debate about whether or not you should pretwist the wire ends together before installing the wire nuts.

Did I stir the hornet's nest? I might as well have said something about installing receptacles ground pin up or ground pin down.  ;)

NO! Don't take the bait! I think we already debated that in another thread. Besides, religion isn't an allowed topic of discussion.
Title: Re: No Box, Safe?
Post by: Jeff Bankston on September 12, 2014, 02:27:01 PM
It's pretty interesting just how emotional this forum gets about apparently simple things such as wire nuts. But it's the simple things that can cause the most damage.

For want of a nail the shoe was lost.
For want of a shoe the horse was lost.
For want of a horse the rider was lost.
For want of a rider the message was lost.
For want of a message the battle was lost.
For want of a battle the kingdom was lost.
And all for the want of a horseshoe nail.
theres no emotion in my replys.
Title: Re: No Box, Safe?
Post by: Jeff Bankston on September 12, 2014, 02:42:24 PM
the reason we install things according to instructions is if theres a problem and we didnt follow the instructions it comes back on us. if we follow instructions and theres a problem its on the manufacturer. i would never use wire nuts that would not twist the wires as its being put on. the srping in the nut cuts grooves in the wires like a screw. when trouble shooting we dont want the wires coming apart when we take a wire nut off. i have had wire nuts come off that someone else put on because they pretwisted the wires and just sorta stuck the nut on and the nut didnt cut any grooves. we always use our side cutters to tighten the nuts and thats one reason i only use Ideal or GB. if you twist the wires first and then put the nut on you will need to tighten more. i have seen wirs twist themselves apart and almost apart and the connection was lost. you would really have to work in the field to see some of improperly installed stuff. i'm always on gaurd when i open a j-box that someone else was in. i'v had nuts fall off wires as i was pulling them out of the box and lots of times those wires are energized. if you decide to pretwist just remember that nut needs to be on there real tight and that requires twisting. i think thats why they say do not pretwist. stranded wires are hard to get the nut off of when done properly. i'v connected a lot of #10 stranded together on 277v lighting runs. well break time is over everybody get back to work.
Title: Re: No Box, Safe?
Post by: Frank DeWitt on September 12, 2014, 05:24:57 PM
Did I stir the hornet's nest? I might as well have said something about installing receptacles ground pin up or ground pin

I have couple of receptacles made to be mounted on a condelet (no code problem there).  They have one ground pin up, and one down.  Every one is happy.
Title: Re: No Box, Safe?
Post by: Mike Sokol on September 12, 2014, 09:20:27 PM
Did I stir the hornet's nest? I might as well have said something about installing receptacles ground pin up or ground pin down.  ;)

I love this forum...  ;D
Title: Re: No Box, Safe?
Post by: Jeff Bankston on September 12, 2014, 10:18:56 PM
Did I stir the hornet's nest?
dont get stung !

http://www.youtube.com/watch?v=A-F9AI8Ry8Q
Title: Re: No Box, Safe?
Post by: Jeff Bankston on September 12, 2014, 10:21:29 PM
Jeff,

This is just a friendly discussion and poll. Please calm down and don't get your (wire)nuts in a twist.  ;D
so does this mean ya'll gonna unfriend me ?
Title: Re: No Box, Safe?
Post by: Frank DeWitt on September 12, 2014, 11:33:37 PM
(http://electrical-contractor.net/BCodes/condulet_recpt_1.JPG)
Title: Re: No Box, Safe?
Post by: Jonathan Johnson on September 13, 2014, 12:58:04 AM
(http://electrical-contractor.net/BCodes/condulet_recpt_1.JPG)
They should've put the ground pins toward the inside, so if something got between the plugs it would be safer.
Title: Re: No Box, Safe?
Post by: Jeff Bankston on September 13, 2014, 01:38:38 AM
(http://electrical-contractor.net/BCodes/condulet_recpt_1.JPG)
the top ground pin should be pointed left and the bottom ground pin should be pointed right.
Title: Re: No Box, Safe?
Post by: Frank DeWitt on September 13, 2014, 08:24:25 AM
the top ground pin should be pointed left and the bottom ground pin should be pointed right.

The best I can do
(http://www.standardelectricsupply.com/productimages/HUBKELE00107_A9_PE_001.jpg)
Title: Re: No Box, Safe?
Post by: Mike Sokol on September 13, 2014, 08:46:03 AM
The best I can do
(http://www.standardelectricsupply.com/productimages/HUBKELE00107_A9_PE_001.jpg)

Fixed it per Jeff's request... Happy now?  ;D
Title: Re: No Box, Safe?
Post by: Frank DeWitt on September 13, 2014, 09:26:37 AM
Fixed it per Jeff's request... Happy now?  ;D

Mike, I am Shocked.  You swapped the hot and neutral (note the long slot)
Your not going to get one of those free testers.  Not now.

I can believe he did that.........
Title: Re: No Box, Safe?
Post by: Jeff Bankston on September 13, 2014, 09:42:00 AM
Fixed it per Jeff's request... Happy now?  ;D
i dont like white. it can only be black.
Title: Re: No Box, Safe?
Post by: Steve M Smith on September 13, 2014, 10:09:59 AM
i dont like white. it can only be black.

How about this?

(http://stevesmithphoto.webs.com/socket.jpg)


Steve.
Title: Re: No Box, Safe?
Post by: Mike Sokol on September 13, 2014, 10:46:20 AM
How about this?

(http://stevesmithphoto.webs.com/socket.jpg)


Steve.


So pretty...  ;)
Title: Re: No Box, Safe?
Post by: Jeff Bankston on September 13, 2014, 01:33:28 PM
How about this?

(http://stevesmithphoto.webs.com/socket.jpg)


Steve.
thats it
Title: Re: No Box, Safe?
Post by: Stephen Swaffer on September 13, 2014, 02:40:27 PM
If you cut the ground prong off your plugs, it won't matter any way.

Jeff, kinda hard to unfriend someone I haven't friended-but then if a man unfriends everyone he has a disagreement with, he will soon be a very lonely man.   At the risk of being accused of ringing religion into the forum, there is a proverb that says as iron sharpeneth iron, so doth a man the countenance of his friend. No sharpening happens without a bit of friction from time to time.  And sharpening seems to be the point of this forum.
Title: Re: No Box, Safe?
Post by: Craig Hauber on September 14, 2014, 12:38:11 AM
3m scotch locks are the worst wire nuts i'v ever seen. even then the improved ones are junk. i never allowed them on my jobs. if the supply house my boss used only had scotch i would tell him to call another supply house and get Ideal or GB wing nuts. a man needs to know how to tighten his nuts and keep the junk nuts out of his trunk.
I can't stand the Buchanan "B-Caps" and it seems our local supply house tries to foist them on the untrained or newbie go-fers that you send to pick up orders. 
Apparently they are now a subsidiary of Ideal so be careful of what you get when specify "Ideal"

That said, the beige Ideal "Twister" nuts are my favorite and a standard 5/16th socket will turn them (which helps sore hands after a long day of wiring)
Title: Re: No Box, Safe?
Post by: Jeff Bankston on September 14, 2014, 02:23:02 AM
Jeff, kinda hard to unfriend someone I haven't friended-but then if a man unfriends everyone he has a disagreement with, he will soon be a very lonely man. 
oops this isnt Facebook ! my bag !
Title: Re: No Box, Safe?
Post by: Jonathan Johnson on September 15, 2014, 12:02:36 AM
Mike, I am Shocked.  You swapped the hot and neutral (note the long slot)
Your not going to get one of those free testers.  Not now.

I can believe he did that.........

Must be an RPBG.
Title: Re: No Box, Safe?
Post by: Jeff Bankston on September 15, 2014, 02:57:26 AM
Must be an RPBG.
a Red Pink Blew and Green. well i be dowg gown !
Title: Re: No Box, Safe?
Post by: Steve M Smith on September 15, 2014, 03:17:44 AM
a Red Pink Blew and Green.

That makes it a bit of an Andy Warhol style multi-socket:

(http://stevesmithphoto.webs.com/RPBG-SKT.jpg)
 
 
Steve.
Title: Re: No Box, Safe?
Post by: Jeff Bankston on September 15, 2014, 05:32:43 AM

That makes it a bit of an Andy Warhol style multi-socket:

(http://stevesmithphoto.webs.com/RPBG-SKT.jpg)
 
 
Steve.
thats eeeit ! that makes me happy :)
Title: Re: No Box, Safe?
Post by: Mike Sokol on September 15, 2014, 07:12:36 AM
Must be an RPBG.

No, it's a GBPR.  ;D
Title: Re: No Box, Safe?
Post by: Jeff Bankston on September 15, 2014, 07:43:27 AM
No, it's a GBPR.  ;D
this makes me sad
Title: Re: No Box, Safe?
Post by: Mike Sokol on September 15, 2014, 09:42:37 AM
this makes me sad

Is this better?  ::)
Title: Re: No Box, Safe?
Post by: Steve M Smith on September 15, 2014, 11:00:02 AM
Someone else can swap the colours around!


Steve.
Title: Re: No Box, Safe?
Post by: Frank DeWitt on September 15, 2014, 11:22:15 AM
I am trying to figure out at what exact point this thread stopped being hot and hit the ground.  Perhaps I have those reversed.  Perhaps it started out well grounded, became hot, and now it is neutral.

(http://photos1.blogger.com/blogger/696/2000/1600/umae.jpg)
Title: Re: No Box, Safe?
Post by: Jeff Bankston on September 15, 2014, 04:42:04 PM
Is this better?  ::)
well.............no. i'm more full of sadness now :( sadder than a 56 oldsmobile and thats really sad. so sad.
Title: Re: No Box, Safe?
Post by: frank kayser on September 15, 2014, 07:17:28 PM
I am trying to figure out at what exact point this thread stopped being hot and hit the ground.  Perhaps I have those reversed.  Perhaps it started out well grounded, became hot, and now it is neutral.

(http://photos1.blogger.com/blogger/696/2000/1600/umae.jpg)
Breaker has been tripped for quite a while - it's been running on whatever electrons are left in the line...
frank
Title: Re: No Box, Safe?
Post by: Mike Sokol on September 15, 2014, 09:40:54 PM
Breaker has been tripped for quite a while - it's been running on whatever electrons are left in the line...
frank

I don't remember where this thread started or how it got so far off track.  :o
Title: Re: No Box, Safe?
Post by: Jeff Bankston on September 15, 2014, 10:25:33 PM
I don't remember where this thread started or how it got so far off track.  :o
somebody went and got a ticket on Amtrak.
Title: Re: No Box, Safe?
Post by: Ray Aberle on September 15, 2014, 11:51:37 PM
somebody went and got a ticket on Amtrak.

.....Amtrak is still around?!?
Title: Re: No Box, Safe?
Post by: Frank DeWitt on September 16, 2014, 09:15:34 AM
.....Amtrak is still around?!?

Sort of   In FY 2012, Amtrak earned approximately $2.877 billion in revenue and incurred approximately $4.036 billion in expense.
Title: Re: No Box, Safe?
Post by: Ray Aberle on September 16, 2014, 09:43:06 AM
Sort of   In FY 2012, Amtrak earned approximately $2.877 billion in revenue and incurred approximately $4.036 billion in expense.

But how does it go, we lose money on every journey but make it up in volume?!?

//avoiding going off topic on the merits of the government, and government-run things, having this habit of spending more then they make...//
Title: Re: No Box, Safe?
Post by: Tim McCulloch on September 16, 2014, 10:19:49 AM
But how does it go, we lose money on every journey but make it up in volume?!?

//avoiding going off topic on the merits of the government, and government-run things, having this habit of spending more then they make...//

Amtrak makes money on the most traveled routes (primarily in the NE) and loses money on the rest.  The problem with the lesser traveled routes is that those who use them really depend on them.  In the free-market model those routes would be eliminated or the price raised to cover costs, effectively screwing the riders who live in less populated areas.  To balance the Amtrak budget they need to up ridership on the money losing routes rather than increasing costs, but the lack of passenger rail facilities (most eliminated over the last 30 years due to air travel) and more convenient scheduling will make this difficult.

Tim 'hoping for new rail connections in Kansas' Mc

"Sons of Pullman porters and sons of engineers/ride their father's magic carpets made of steel"  - Arlo Guthrie
Title: Re: No Box, Safe?
Post by: frank kayser on September 16, 2014, 10:25:17 AM


"Sons of Pullman porters and sons of engineers/ride their father's magic carpets made of steel"  - Arlo Guthrie


Sorry, Tim.  The late, Great, Steve Goodman.
Granted, the song might be largely unknown without the wonderful performance and celebrity of Arlo.


frank
Title: Re: No Box, Safe?
Post by: Mike Sokol on September 16, 2014, 12:54:20 PM

Sorry, Tim.  The late, Great, Steve Goodman.
Granted, the song might be largely unknown without the wonderful performance and celebrity of Arlo.


frank

Can somebody PLEASE get this thread back OT?  :o
Title: Re: No Box, Safe?
Post by: Steve M Smith on September 16, 2014, 01:07:07 PM
Can somebody PLEASE get this thread back OT?

I will have a go.

What about these boxes which mount into the plasterboard? (or drywall as I think you call it).

(http://www.switchedonltd.co.uk/ekmps/shops/switchedon/images/35mm-2-gang-fast-fix-dry-lining-box-for-plasterboard-360-p.jpg)


Steve.
Title: Re: No Box, Safe?
Post by: Jonathan Johnson on September 16, 2014, 01:22:55 PM
Can somebody PLEASE get this thread back OT?  :o

One thing I notice from the OP is that there is no strain relief on the cables entering the mounting rings (can't call them boxes). Here in the USA, the NEC requires strain relief either via fastening the cable within 6" of the box (in the case of those 29c plastic nail-on boxes with no integral clamps) or a clamp on the box itself. The strain relief is to ensure that tension on the cables does not put stress on the electrical connections.

Without seeing the devices that the Australian electricians will mount on these rings, we can't really judge that it's unsafe. If the devices include some means of strain relief, at least that concern is addressed. Now as for boxlessness, the safety of that is debatable. There may be situations where a box really adds no appreciable safety improvement. For example, if the wall is framed with steel studs then covered with metal lath and plaster, there's really nothing in there to catch fire. The whole thing becomes an electrical box. Obviously that's not the case with the OP's example, but it IS a case where a box might not be needed. But good luck convincing your AHJ of that. :)
Title: Re: No Box, Safe?
Post by: Jeff Bankston on September 16, 2014, 03:48:03 PM
I will have a go.

What about these boxes which mount into the plasterboard? (or drywall as I think you call it).

(http://www.switchedonltd.co.uk/ekmps/shops/switchedon/images/35mm-2-gang-fast-fix-dry-lining-box-for-plasterboard-360-p.jpg)


Steve.
i will never use a plastic. they are junk. i have seen and ben told by others that the plactic boxes in their houses are broken. plastic isnt allowed in commercial(yet). metal boxes are the only way to go.
Title: Re: No Box, Safe?
Post by: Steve M Smith on September 16, 2014, 05:02:50 PM
I wouldn't use them by choice either, although I have used them a couple of times where using a metal box was not possible.

What if they were a different colour?!


Steve.
Title: Re: No Box, Safe?
Post by: Jeff Bankston on September 16, 2014, 05:24:00 PM
I wouldn't use them by choice either, although I have used them a couple of times where using a metal box was not possible.

What if they were a different colour?!


Steve.
green.....no blue
Title: Re: No Box, Safe?
Post by: Steve M Smith on September 16, 2014, 06:10:28 PM
I have seen them with red, yellow and blue threaded insert clamp pieces but no green... sorry!


Steve.
Title: Re: No Box, Safe?
Post by: Jeff Bankston on September 16, 2014, 06:12:54 PM
I have seen them with red, yellow and blue threaded insert clamp pieces but no green... sorry!


Steve.
the sadness creeps back :(
Title: Re: No Box, Safe?
Post by: Stephen Swaffer on September 16, 2014, 10:19:06 PM
Going strictly by the NEC, non-metallic boxes are acceptable anywhere you are allowed to use nonmetallic sheathed cable, or knob and tube wiring or open wiring on insulators(NEC 2011 314.3).  NM (romex) is allowed -by the NEC-in certain types of construction (wood frame essentially) no matter the use.  I realize that most local AHJ will not allow NM in commercial-but that is actually going above and beyond the NEC.

Which are better?  PVC may get hard and crack or strip threads.  Metal often rusts-and threads get stripped.  Pick your poison-they all can be a problem.

Jonathan is right as far as fire with metal stud and plaster-but metal boxes require bonding.  I would think the code addresses bonding metal studs-but not sure if it happens?  I haven't actually done any new wiring with metal studs, though.  Without a box you leave open the possibility of conductors touching something metalic they should not they may not be adequately bonded, don't you?

As for color-stop by the paint department at your favorite store-they sell spray paint for plastic and for metal in a large variety of colors.  Then let the AHJ stuggle to find chapter and verse why you can't paint the boxes your favorite color so you get a warm fuzzy feeling installing them.
Title: Re: No Box, Safe?
Post by: Jeff Bankston on September 17, 2014, 02:25:37 AM
Going strictly by the NEC, non-metallic boxes are acceptable anywhere you are allowed to use nonmetallic sheathed cable, or knob and tube wiring or open wiring on insulators(NEC 2011 314.3).  NM (romex) is allowed -by the NEC-in certain types of construction (wood frame essentially) no matter the use.  I realize that most local AHJ will not allow NM in commercial-but that is actually going above and beyond the NEC.

Which are better?  PVC may get hard and crack or strip threads.  Metal often rusts-and threads get stripped.  Pick your poison-they all can be a problem.

Jonathan is right as far as fire with metal stud and plaster-but metal boxes require bonding.  I would think the code addresses bonding metal studs-but not sure if it happens?  I haven't actually done any new wiring with metal studs, though.  Without a box you leave open the possibility of conductors touching something metalic they should not they may not be adequately bonded, don't you?

As for color-stop by the paint department at your favorite store-they sell spray paint for plastic and for metal in a large variety of colors.  Then let the AHJ stuggle to find chapter and verse why you can't paint the boxes your favorite color so you get a warm fuzzy feeling installing them.
metal boxes are screwed to metal studs or other metal mounting devices that are screwed to metal studs that the metal boxes are screwed to. a ground pigtal wire is screwed to the box whick is screwed to the stud and the studs are all screwed together and we are all screwed and bonded.
Title: Re: No Box, Safe?
Post by: Mike Sokol on September 17, 2014, 07:14:17 AM
metal boxes are screwed to metal studs or other metal mounting devices that are screwed to metal studs that the metal boxes are screwed to. a ground pigtal wire is screwed to the box whick is screwed to the stud and the studs are all screwed together and we are all screwed and bonded.

That doesn't work for a "technical" ground since connecting your audio grounds to building steel is the "best" way to create a bunch of ground loop hum. In that case, the best way is to run a second technical ground wire (green/yellow-stripe) to isolated ground receptacles. I've talked to a few inspectors in Maryland, and they do insist that metal boxes are used in commercial installation, but don't insist that they're bonded to building steel since they're bonded to the BX cable. It seems there's a lot of local code differences as to proper bonding/grounding of receptacles. If you CAN use non-metalic boxes and Romex according to your local code, that would reduce a lot of ground-loop hum.
 
Title: Re: No Box, Safe?
Post by: Jeff Bankston on September 17, 2014, 08:30:12 AM
That doesn't work for a "technical" ground since connecting your audio grounds to building steel is the "best" way to create a bunch of ground loop hum. In that case, the best way is to run a second technical ground wire (green/yellow-stripe) to isolated ground receptacles. I've talked to a few inspectors in Maryland, and they do insist that metal boxes are used in commercial installation, but don't insist that they're bonded to building steel since they're bonded to the BX cable. It seems there's a lot of local code differences as to proper bonding/grounding of receptacles. If you CAN use non-metalic boxes and Romex according to your local code, that would reduce a lot of ground-loop hum.
the way i posted is the way we have to do ot in la. tis ben done that way since i move here in 1987. and there no way to get around it either. a metal box screwed to a metal stud. and every conduit has to have a ground wire and ever box has to have a ground pig tail and every concentric knock out out has to have a ground bushing with a seperate ground wire. they have had lots of conduits pulled apart in earthquakes and they want everyhting grounded. the emt/gal/metal flex is strapped or tie wired to the metal studs. mc/ac cable is done the same way. the only way to not have the the electrical boxes and conduit fastened to the metal studs is use all plastic and thats not allowed. in la they still consider the conduit a mechanical ground and the ground wire the electrical ground. they dont care about audio hum all the care about is everything staying bonded and grounded in an earthquake. these earthquakes can shake stuff apart. i never buy concentric ko boxes. i buy 4s and 5s boxex with the ko's i need and punch my own holes in larger boxes.
Title: Re: No Box, Safe?
Post by: Frank DeWitt on September 17, 2014, 10:04:17 AM
and there no way to get around it either.
snip
they dont care about audio hum all the care about is everything staying bonded and grounded in an earthquake.

One way around it most places is to use isolated ground receptacles.  The strap that connects the receptacles to the box is NOT connected to the safety ground terminals in the receptacle.  They are connected with a separate ground wire back to the panel,  not to the box.

(http://s453.photobucket.com/user/jdandy_photos/media/IsolatedGroundReceptacle.jpg.html)
Title: Re: No Box, Safe?
Post by: Mike Sokol on September 17, 2014, 10:45:26 AM
One way around it most places is to use isolated ground receptacles.  The strap that connects the receptacles to the box is NOT connected to the safety ground terminals in the receptacle.  They are connected with a separate ground wire back to the panel,  not to the box.

(http://s453.photobucket.com/user/jdandy_photos/media/IsolatedGroundReceptacle.jpg.html)

Frank, but once the EGC (ground) wire is bonded to the steel at the receptacle, the damage to the audio ground is already done. At that point it doesn't matter if it's an isolated ground receptacle or not. You have to have an EGC/Audio ground all the way back to the service panel's EGC/GEC bonding point that DOESN'T touch building steel anywhere on its path. That's the tricky part, since by definition any armored cable and metal boxes will be attached to building steel. And it only takes one connection like that (accidental or on purpose) to contaminate a technical ground. I did a consult with a church in Texas last year that used metallic conduit for the ONLY ground. Of course, it hummed like crazy since there was several volts difference various grounds that the audio was plugged into. Rather than rewire everything (which, by the way was recently passed by a local inspector) we just added in a bunch of WW ISO-2 audio isolation boxes between the mixer outputs and the amp rack that was 100 feet away. They already had a bunch of DI boxes with appropriate ground lift switches on stage, but their main hum was from a ground loop current between the console position and the amp rack. I didn't measure the actual current, but I'm guessing it was at least a couple amps since the voltage differential varied around 1.5 to 2 volts AC between the various outlets. That was the hint that something was terribly wrong with the audio ground.
Title: Re: No Box, Safe?
Post by: Frank DeWitt on September 17, 2014, 11:04:43 AM
Frank, but once the EGC (ground) wire is bonded to the steel at the receptacle, the damage to the audio ground is already done.

Yes,  I think we are in agreement.  Mount and ground the box any way you wish / required by code, Run a ground wire to the box, boxes, or whatever. Attach the box to the building steel ETC.  Then run a separate wire from the ground screw on the receptacle (different color wire)  back to the panel.  Yes, it is a pain. It is easy for someone to mess it up and hard to find, and it is only practical in new construction, but it can be done.  I worked in one company that had a isolated ground system in a large experimental lab (think football field size)  They actual monitored the current on the isolated ground system. If it changed dramatically a alarm went off.

Me in my old church.  I use a lot of audio isolation transformers, just like you did.   
Title: Re: No Box, Safe?
Post by: Mike Sokol on September 17, 2014, 11:52:40 AM
Me in my old church.  I use a lot of audio isolation transformers, just like you did.

+1 - Many times that's the cheap way out. What I do for this type of testing is keep a couple of cheap/orange extension cords in my truck. They're really not good enough for audio power, but plenty fine for testing grounds. Then plug the male ends into outlets at the console and amp rack positions. Hold the two "hot" ends next to each other and meter for AC voltage between the two grounds. It should read VERY close to 0 volts. My tests show that even 1/10th of a volt difference between two outlet grounds can make a lot of amplifiers and speakers hum. (Yes, the pin-1 problem). You can confirm this by simply clamping an ammeter around the outside of the XLR return from the board to the amp rack. Since the return current path is external to the XLR shield (the building steel) there's no need to split out the twisted pair from the shield. In fact, you can clamp a $50 ammeter around the entire analog snake to check for currents. Even 100 mA is a significant ground loop current that can cause a lot of grief. The audio iso transformers isolate the two shields from each other. And so no shield current = no ground loop hum. It really is easy to troubleshoot like that since a clamp ammeter is completely passive and you can use it in the middle of the production with the sound system running to find a hum, then swap in an audio iso transformer at break. And fixing the hum in a pa system during a show or worship service elevates you to super audio dog status (or something like that).
Title: Re: No Box, Safe?
Post by: Steve M Smith on September 17, 2014, 12:40:34 PM
Do you actually need the isolation of a transformer in these cases or would the normal 10 ohm resistor and 0.1uF capacitor as used in active DIs to 'lift' the ground do the trick?


Steve.
Title: Re: No Box, Safe?
Post by: Jonathan Johnson on September 17, 2014, 02:17:38 PM
Going strictly by the NEC, non-metallic boxes are acceptable anywhere you are allowed to use nonmetallic sheathed cable, or knob and tube wiring or open wiring on insulators(NEC 2011 314.3).  NM (romex) is allowed -by the NEC-in certain types of construction (wood frame essentially) no matter the use.  I realize that most local AHJ will not allow NM in commercial-but that is actually going above and beyond the NEC.

Which are better?  PVC may get hard and crack or strip threads.  Metal often rusts-and threads get stripped.  Pick your poison-they all can be a problem.


If manufacturers' sales literature is to be believed, plastic is superior to metal for fire resistance.

http://www.carlonsales.com/techinfo/codesstandards/CS-Fire_PVC_Building_Codes.pdf
Title: Re: No Box, Safe?
Post by: Frank DeWitt on September 17, 2014, 02:28:10 PM
+1 - Many times that's the cheap way out. What I do for this type of testing is keep a couple of cheap/orange extension cords in my truck. They're really not good enough for audio power, but plenty fine for testing grounds. Then plug the male ends into outlets at the console and amp rack positions. Hold the two "hot" ends next to each other and meter for AC voltage between the two grounds. It should read VERY close to 0 volts. My tests show that even 1/10th of a volt difference between two outlet grounds can make a lot of amplifiers and speakers hum. (Yes, the pin-1 problem). You can confirm this by simply clamping an ammeter around the outside of the XLR return from the board to the amp rack. Since the return current path is external to the XLR shield (the building steel) there's no need to split out the twisted pair from the shield. In fact, you can clamp a $50 ammeter around the entire analog snake to check for currents. Even 100 mA is a significant ground loop current that can cause a lot of grief. The audio iso transformers isolate the two shields from each other. And so no shield current = no ground loop hum. It really is easy to troubleshoot like that since a clamp ammeter is completely passive and you can use it in the middle of the production with the sound system running to find a hum, then swap in an audio iso transformer at break. And fixing the hum in a pa system during a show or worship service elevates you to super audio dog status (or something like that).

Heads up.  This needs to go on the wall or in the note book or some place handy.  In one paragraph you explained.
1   what a ground loop is
2   How to tell if you have one
3.  How to tell with a clamp on amp meter
4   What to do about it.
Title: Re: No Box, Safe?
Post by: Jeff Bankston on September 17, 2014, 02:33:57 PM
One way around it most places is to use isolated ground receptacles.  The strap that connects the receptacles to the box is NOT connected to the safety ground terminals in the receptacle.  They are connected with a separate ground wire back to the panel,  not to the box.

(http://s453.photobucket.com/user/jdandy_photos/media/IsolatedGroundReceptacle.jpg.html)
we can only install what the customer wants or what the blueprints specify. you must understand WE the electricians HAVE TO follow the plans. also if we decided to install ig recepticals when we are told to install regular ones WHO pays for that ? we could get sued and our business license pulled for selling a customer something they did not ask for. the problem is some of you guys dont have a clue when it comes to the business of electrical work. if i install ig recepts when a customer didnt ask for them i would have to pay the extra and that aint gonna happen. what needs to be done is the code changed for places that have sound systems.
Title: Re: No Box, Safe?
Post by: Frank DeWitt on September 17, 2014, 02:43:40 PM
Do you actually need the isolation of a transformer in these cases or would the normal 10 ohm resistor and 0.1uF capacitor as used in active DIs to 'lift' the ground do the trick?
Steve.

The resistor trick is used in cheep active DIs.  Not in ones like Radial

If we take Mikes numbers that 100 ma causes a lot of hum then if you start with 100 ma and lets assume your resistance from the whole ground loop (audio cable shield and building grounds) is 5 ohms then adding 10 ohms you have  .5 volts across 15 ohms you cut the current to 33 ma so you cut your hum to 1/3 of what it was.

If you had 2 volts like Mike has reported seeing then your 10 ohm resistor gets the current down to 133 ma.  HUM.

Going from a mixer to a amp rack you don't need phantom power so I would try a jumper cable with a open pin 1 first.  Then when I still had hum I would put the transformer in.  Grin

Transformers are a great solid fix.  The good ones (that don't change the sound) cost money but the problem goes away.
Title: Re: No Box, Safe?
Post by: Frank DeWitt on September 17, 2014, 03:02:48 PM
we can only install what the customer wants or what the blueprints specify. you must understand WE the electricians HAVE TO follow the plans. also if we decided to install ig recepticals when we are told to install regular ones WHO pays for that ? we could get sued and our business license pulled for selling a customer something they did not ask for. the problem is some of you guys dont have a clue when it comes to the business of electrical work. if i install ig recepts when a customer didnt ask for them i would have to pay the extra and that aint gonna happen. what needs to be done is the code changed for places that have sound systems.

Absolutely but hopefully some people reading this list or other good lists will specify a AC power system that is audio friendly.  As one example,  I belong to a growing church and I have a folder marked "New Building"  There is info on isolated grounds, separate Huge raceways for signal between the booth and back stage, amp rack placement and orientation, alternatives to floor pockets ETC.   In other words, I may be the customer one of these years.

Wait till the electrician hears I want the hot and neutral twisted.
Title: Re: No Box, Safe?
Post by: Mike Sokol on September 17, 2014, 03:09:43 PM
Heads up.  This needs to go on the wall or in the note book or some place handy.  In one paragraph you explained.
1   what a ground loop is
2   How to tell if you have one
3.  How to tell with a clamp on amp meter
4   What to do about it.

Should I make this a new topic and write a short essay on it? That could be useful, I think....

Title: Re: No Box, Safe?
Post by: Tommy Peel on September 17, 2014, 04:05:45 PM
.....Amtrak is still around?!?
<back off track>
Yeah... I get stopped by one in one of the towns I drive through on the way to/from work occasionally. The train station is right by one of the main roads through town.

Of course being a local I know the way around it.  8)
</back off track>
<back on track>
Title: Re: No Box, Safe?
Post by: Steve M Smith on September 17, 2014, 04:24:32 PM
When did railway (or railroad) stations become train stations?


Steve.
Title: Re: No Box, Safe?
Post by: Frank DeWitt on September 17, 2014, 04:30:07 PM
Should I make this a new topic and write a short essay on it? That could be useful, I think....

Good question,  Can it be short?  To stand alone it should also include what a ground isn't  (hot all hum comes from ground loops.
so lets see

1 Hum is bad but is it a ground loop?
       Other common causes.
       How to tell.
2.  OK  Ground loop where?  How to tell
     The right way to break it and keep audio
           Balanced with phantom
           Balanced w/o phantom
                 mic level or line
                        install the fix at what end?
3  How not to fix it?

Perhaps some more on the other causes of hum and there fix
Do include your clamp on amp probe use.  I have never seen anyone else use it or talk about it.

Or just write a book and get rich?  Probably not.
Title: Re: No Box, Safe?
Post by: Stephen Swaffer on September 17, 2014, 04:36:27 PM
we can only install what the customer wants or what the blueprints specify. you must understand WE the electricians HAVE TO follow the plans..... if i install ig recepts when a customer didnt ask for them i would have to pay the extra and that aint gonna happen. what needs to be done is the code changed for places that have sound systems.

By definition the NEC is concerned with fire and personel safety-proper functioning is not really their concern-and I would argue it should not be.  What SHOULD happen is that the people making the plans should be professional and competent enough to draw up plans that take into account the intended use of the facility and spec proper wiring.  I just did a remodel that spec'd isolated ground receptacles in 2 locations for IT equipment.  (Finding MC/BX cable with 2 ground wires is a pain-at least in Iowa-fortunately my inspector allowed me to remark a wire as the iso ground.) There is nothing preventing their being specified for audio or other technical uses.

Code was never intended to be "best practices"-but rather a minimum, hopefully safe install.
Title: Re: No Box, Safe?
Post by: Tommy Peel on September 17, 2014, 04:56:32 PM
When did railway (or railroad) stations become train stations?


Steve.
I don't know... Maybe it's a Texas thing. That's what I've always heard them called.

Sent from my Moto X (XT1053) using Tapatalk

Title: Re: No Box, Safe?
Post by: Mark Cadwallader on September 17, 2014, 05:32:19 PM
When did railway (or railroad) stations become train stations?


Steve.

Shortly after "automobiles" were referred to as "cars."  Don't let me get started on motorcycles being called "bikes"....

Mike, a sticky article on hum and ground loops would be great. Mark C.
Title: Re: No Box, Safe?
Post by: Mike Sokol on September 17, 2014, 10:53:22 PM
Good question,  Can it be short?  To stand alone it should also include what a ground isn't  (hot all hum comes from ground loops.
so lets see

1 Hum is bad but is it a ground loop?
       Other common causes.
       How to tell.
2.  OK  Ground loop where?  How to tell
     The right way to break it and keep audio
           Balanced with phantom
           Balanced w/o phantom
                 mic level or line
                        install the fix at what end?
3  How not to fix it?

Perhaps some more on the other causes of hum and there fix
Do include your clamp on amp probe use.  I have never seen anyone else use it or talk about it.

Or just write a book and get rich?  Probably not.

Actually, my next book is going to be "No-Shock-Zone for Sound Systems" or something like that. I'm writing it over the winter and should release it next spring. One full chapter is dedicated to identifying and solving ground loop hums in sound systems.

While my editor says I can't write my own name in less than 250 words (he's probably correct) I can probably boil this procedure down to a simple bullet-point list of how to test for ground loop currents with possible solutions in order of preference and price. That would make for a good chapter close, especially if it could fit on a pocket card.

If I do come up with a bullet-point test list for ground loop hum, then you guys will need to test it and give me feedback on the procedure. Does that sound like a fair deal?  8)
Title: Re: No Box, Safe?
Post by: Frank DeWitt on September 17, 2014, 11:13:31 PM
.
If I do come up with a bullet-point test list for ground loop hum, then you guys will need to test it and give me feedback on the procedure. Does that sound like a fair deal?  8)

I would like to be in that loop.  Please keep us current on it.
Title: Re: No Box, Safe?
Post by: Jeff Bankston on September 17, 2014, 11:40:30 PM
When did railway (or railroad) stations become train stations?


Steve.
Dont know. Got to do with where choo choo go. Mongo only pawn in game of life.
Title: Re: No Box, Safe?
Post by: Jeff Bankston on September 17, 2014, 11:55:48 PM
When a building or club design is in the works the electrical architect designs the circuts for the code lighting and power requirements. Its up to the business owner to know that they need to specify seperate panel(s) for sound system use only. There would be a panel for general receptical/lighting use and panel(s) that only power sound system recpticals. The sound system panel(s) can power multiple I.G. receptiacls on the same circut , deticated circut I.G. recepticals , and the seperate circut I.G. receptical. The panel(s) can be powered from an isolation transformer and would have its own grounding wire to the cold water pipe , etc. BUT this has to be part of the design. I wired a few nightclubs and the club owners didnt know anyting about electrical. They are businessmen not electricians. There is the cost factor and extra panel(s) and transformers and I.G. recepticals can easliy add a 5 gigit cost factor that the owner(s) might not want to spend to get better sound. We played in clubs that had awful house pa systems and when i said they otta get a better sounding pa the response was > the people come and drink and are probably to drunk to know or even care. It all comes down to money. If th customers complain about the sound the club owner(s) might do something about it. All they seen to care about is if its loud enough.

btw I have about 80 HO locomotives. no amtrak
Title: Re: No Box, Safe?
Post by: Steve M Smith on September 18, 2014, 01:42:30 AM
Great thread.  I think we have about seven separate subjects being discussed... eight now!


Steve.
Title: Re: No Box, Safe?
Post by: Jonathan Johnson on September 18, 2014, 01:55:56 AM
Great thread.  I think we have about seven separate subjects being discussed... eight now!


Steve.

No conversation is complete unless it involves bathroom humor. Or humour, if you prefer.
Title: Re: No Box, Safe?
Post by: Scott Holtzman on September 18, 2014, 02:42:46 AM
No conversation is complete unless it involves bathroom humor. Or humour, if you prefer.

That was covered awhile ago when the wire nuts came into play.

This thread is much like how my brain works.  I have enjoyed reading it.

Title: Re: No Box, Safe?
Post by: Jeff Bankston on September 18, 2014, 03:38:55 AM
next topic > how to record a song
http://www.youtube.com/watch?v=FyT_2vV1jEw
Title: Re: No Box, Safe?
Post by: Mike Sokol on September 18, 2014, 09:17:34 AM
No conversation is complete unless it involves bathroom humor. Or humour, if you prefer.

Happy now???  ;D
Title: Re: No Box, Safe?
Post by: Mike Sokol on September 18, 2014, 09:27:22 AM
I would like to be in that loop.  Please keep us current on it.

OK, next week I'm going to start a ground-loop troubleshooting thread and make it a sticky. After all, this is the AC Power & Grounding forum, so that's about as OT as it gets. Frank, and anyone who wants to be part of the inner circle, please contact me first to discuss specifics on what would be useful for the group. I have a LOT of different tests I've developed, many of which won't be useful for road-dog situations. But I have a few really simple tests in mind (for instance - clamp ammeter around the entire XLR cable) that should be really handy for hum troubleshooting during a live gig or fixing a mature install. I don't want to spend the time just yet on a guide as to how new installation power should be designed for best audio quality, simply because it would have to cover so many local codes.  That's the stuff that will go into my book.

Shoot me an email at [email protected] with the subject line Ground Loop and let's do a little brainstorming.
Title: Re: No Box, Safe?
Post by: Lyle Williams on September 26, 2014, 04:50:23 AM
Sorry, very late to the party.

The original photo is completely normal in Australia.  I think we have less electrocutions per capita than the US.

While there are wires shown taped together, these are not yet energised.  The photo was taken while the wiring was being roughed in.  All the wires end up screwed down deep inside power outlets and switches.  If wires are joined outside an outlet or switch, it is done in a junction box.
Title: Re: No Box, Safe?
Post by: Jonathan Johnson on September 26, 2014, 11:54:14 AM
The original photo is completely normal in Australia.  I think we have less electrocutions per capita than the US.

While there are wires shown taped together, these are not yet energised.  The photo was taken while the wiring was being roughed in.  All the wires end up screwed down deep inside power outlets and switches.  If wires are joined outside an outlet or switch, it is done in a junction box.

There, now we have an answer to a point I made in earlier post (that probably got lost in the shuffle):

Without seeing the devices that the Australian electricians will mount on these rings, we can't really judge that it's unsafe. If the devices include some means of strain relief, at least that concern is addressed...

Still might be nice to have a picture of the devices with the wires installed but not completely assembled, so we can see just how the connections and strain relief work. Not that it's useful for us in the United States to know how to wire an assembly we'll probably never lay hands on, but it's still nice to know.
Title: Re: No Box, Safe?
Post by: Steve M Smith on September 26, 2014, 12:52:19 PM
Still might be nice to have a picture of the devices with the wires installed but not completely assembled, so we can see just how the connections and strain relief work.

You have strain relief on internal boxes?  What would be causing any strain?

This is what it looks like in the UK:

(http://content5.videojug.com/8d/8dba308a-e455-c826-0c33-ff0008cce289/how-to-wire-wall-sockets.WidePlayer.jpg)


Steve.
Title: Re: No Box, Safe?
Post by: Jonathan Johnson on September 26, 2014, 01:07:48 PM
You have strain relief on internal boxes?  What would be causing any strain?

The National Electrical Code (the code used in most jurisdictions in the United States) requires an integral strain relief for all cables entering any electrical box. The only exception is for nonmetallic, single-gang boxes which don't require an integral strain relief IF the cable is fastened to the building structure within 6" (13 cm) of the box entry.

Cables must also be fastened to the building structure at specified distances (I think it's a maximum of 4 feet, or just over a meter). The only exception to this rule is for "old work" where the wire is fished through enclosed ceiling and wall cavities, where it would be impractical to fasten the cable.

So why are we required to have strain relief? Probably because in many situations, the walls are left unfinished so the wiring remains exposed. Also, our construction practices often require wiring to be energized before the drywall is completed. As the electrical inspector won't necessarily know which walls will be finished and which will be left open for future finishing, they treat it all as though it will remain unfinished. (Where the wiring is intended to be permanently exposed, nonmetallic cable must be enclosed in conduit at any point below 8 ft/2.5m above the finished floor.) With that in mind, there is a LOT of construction that remains "unfinished" forever, but because it's "unfinished" then it's not "permanent" so isn't installed in conduit.  :o )

So the strain relief is required to keep stress off of the connections during the time between wiring and the wall is finished to conceal the wiring.
Title: Re: No Box, Safe?
Post by: Steve M Smith on September 26, 2014, 01:12:08 PM
So why are we required to have strain relief? Probably because in many situations, the walls are left unfinished so the wiring remains exposed. Also, our construction practices often require wiring to be energized before the drywall is completed.

Ours are usually done the other way round.  The wiring is put in place and pokes out through holes in the board, then when it is fully boarded, the boxes are put in and connected up.


Steve.
Title: Re: No Box, Safe?
Post by: Frank DeWitt on September 26, 2014, 02:18:09 PM
Ours are usually done the other way round.  The wiring is put in place and pokes out through holes in the board, then when it is fully boarded, the boxes are put in and connected up.

Steve.

When I built my house in 1984 in New York state wiring was done in 3 stages with a inspection at each stage.
1.  Meter housing and circuit breaker panel  and associated wiring installed.
       Once that was inspected then a meter would be installed by the power company and the power turned on.
2.  "Rough in wiring"  Basically what was shown in the first photo but to US code  (Wiring boxes, wiring fastened as required ETC.
        Once this was inspected the dry wall and other covering could be installed.  It was understood that a couple of circuits using this wiring would have outlets installed, and be connected and used during construction.    Usually one outlet on each floor and two or more next to the panel.
3.  Instillation of all devices.  Outlets, switches, light fixtures, ETC complete with cover plates.  The only exception was that the circuit breaker panel cover was to be displayed next to the panel to prove you had not lost it but not installed.   At this inspection the inspector has the option of checking each outlet for proper wiring with a 3 bulb tester, and asking you to remove any cover plates to check your work.  If you pass. Your wiring is complete. A report is turned over to the town and is part of the inspections need for a certificate of occupancy.

I passed. 


Title: Re: No Box, Safe?
Post by: Steve M Smith on September 26, 2014, 02:21:29 PM
Most UK electricians are allowed to self certify their wiring now as long as they have had the correct training.


Steve.
Title: Re: No Box, Safe?
Post by: Stephen Swaffer on September 26, 2014, 02:33:36 PM
You have strain relief on internal boxes?  What would be causing any strain?

Homeowners using wire as a clothesline in the basement, someone fishing a new wire and hooking an existing etc,
Title: Re: No Box, Safe?
Post by: Steve M Smith on September 26, 2014, 02:40:39 PM
Homeowners using wire as a clothesline in the basement

Back in the 1960s, my mother worked in a hair stylists.  In their basement they did exactly this to hang up the washed towels to dry!


Steve.
Title: Re: No Box, Safe?
Post by: Lyle Williams on September 27, 2014, 11:57:35 PM
There, now we have an answer to a point I made in earlier post (that probably got lost in the shuffle):

Still might be nice to have a picture of the devices with the wires installed but not completely assembled, so we can see just how the connections and strain relief work. Not that it's useful for us in the United States to know how to wire an assembly we'll probably never lay hands on, but it's still nice to know.

http://en.m.wikipedia.org/wiki/AS/NZS_3112#/image/File:Dual_3_Pin_Power_Outlet_-_Construction.jpg

There is no separate strain relief.  Not securing wiring is deliberate.  It's harder to put a nail through a wire that can move out of the way.

Plus RCD/GFCIs are mandatory down here.