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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: Tom Bourke on January 25, 2014, 09:13:22 pm

Title: Just a reminder to check the power at your distro as well as the wall.
Post by: Tom Bourke on January 25, 2014, 09:13:22 pm
Was working as an electrician on a show today.  Tied in several distros.  Then they had me add a small distro via the cam outs of one already tied in that I had not done.  Hooked it all up and then metered the test points on the new distro.  Ground was floating!  Checked the original distro and it was good.  Went to check the cams and the end came off the feeder cable!
Title: Re: Just a reminder to check the power at your distro as well as the wall.
Post by: Steve M Smith on January 26, 2014, 03:31:15 am
Went to check the cams and the end came off the feeder cable!

Sorry, it's probably just me being English and not aware of the term but what do you mean by cam?  We probably call it something else.


Steve.
Title: Re: Just a reminder to check the power at your distro as well as the wall.
Post by: Tim McCulloch on January 26, 2014, 07:31:40 am
Sorry, it's probably just me being English and not aware of the term but what do you mean by cam?  We probably call it something else.


Steve.

Cam-Lok®.  A trademarked name for a single pole, separable connector.

(https://encrypted-tbn0.gstatic.com/images?q=tbn:ANd9GcQbbP4_KdLKcy2si3slxJrGx6sZvirh1Fok_hLU1X-VjmJGpNxgEw)
Title: Re: Just a reminder to check the power at your distro as well as the wall.
Post by: Mike Sokol on January 26, 2014, 09:29:29 am
Was working as an electrician on a show today.  Tied in several distros.  Then they had me add a small distro via the cam outs of one already tied in that I had not done.  Hooked it all up and then metered the test points on the new distro.  Ground was floating!  Checked the original distro and it was good.  Went to check the cams and the end came off the feeder cable!

+1 on this... I know I'm paranoid, but am I paranoid enough? Cam-Locks take a lot of abuse dragging them around, so never trust anything. As a final test for back-line grounds I like to poke a NCVT at a few microphones (just one should be sufficient) and all stage amps or DI'ed instruments (musicians  are notorious for cutting off the ground prongs on their power cords). Generally any open grounds will allow the gear chassis to float up to at least 1/2 of line voltage (120/60 volts in the USA and 230/115 volts in the UK). While many of these chassis voltages will be low-current (less than a few mA), some will have much higher potential fault currents (1 to 20 amps) with 120-volts on the mics or stage amp chassis, and thus be VERY dangerous to performers and technicians.   

Every NCVT (Non Contact Voltage Tester) that I've reviewed, that was rated for 90 to 600/1,000 volts, will trigger on a large surface charged with as little as 40 volts or so. You can purchase a NCVT at any big-box store or online for $15 to $25. A standard sensitivity NCVT is also useful for testing receptacles (outlets) for proper H-N polarity. While generally not an immediate danger, a swapped Hot and Neutral hints that the wiring was done incorrectly and could have other (more dangerous) problems. Here's a video I did for RVtravel on how to use a NCVT to check outlet H-N polarity, but it's exactly the same procedure for testing back-line outlets: http://www.youtube.com/watch?v=jF3Ntoa8ab8 (http://www.youtube.com/watch?v=jF3Ntoa8ab8)
Title: Re: Just a reminder to check the power at your distro as well as the wall.
Post by: Tom Bourke on January 26, 2014, 10:17:44 am
Lately I have been carrying a pair of Fluke NCVT's.  One fits on my key-ring and has dual voltage (via two colors) and a flashlight.  The other is the full size 90 to 1000V unit.  I find them to be great time savers in trouble shooting lighting rigs. It is almost like you can look into the cables and see power.  You still need a full meter, but not as often.  Had one instance of a 220V adapter wired with the same phase on each line.  Tested as it should with the noncontact.  However 120V to ground on each and 0 volts phase to phase was the giveaway.  It was an interesting day.
Title: Re: Just a reminder to check the power at your distro as well as the wall.
Post by: Mike Sokol on January 26, 2014, 10:35:19 am
Lately I have been carrying a pair of Fluke NCVT's.  One fits on my key-ring and has dual voltage (via two colors) and a flashlight.  The other is the full size 90 to 1000V unit.  I find them to be great time savers in trouble shooting lighting rigs. It is almost like you can look into the cables and see power.  You still need a full meter, but not as often.  Had one instance of a 220V adapter wired with the same phase on each line.  Tested as it should with the noncontact.  However 120V to ground on each and 0 volts phase to phase was the giveaway.  It was an interesting day.

Of course a NCVT is not a substitute for a good voltmeter. But you are correct that it's a great tool that can help you speed up troubleshooting. The key is to use all your test gear enough to know when something just doesn't add up. I teach my basic electronics students to predict what voltage they should measure BEFORE they turn on a meter and stick in the probes. And then we discuss the implications of getting various unpredicted meter readings.

As the OP noted, it's best to measure twice and avoid getting shocked once (or something like that)...
Title: Re: Just a reminder to check the power at your distro as well as the wall.
Post by: frank kayser on January 26, 2014, 02:46:06 pm
Was working as an electrician on a show today.  Tied in several distros.  Then they had me add a small distro via the cam outs of one already tied in that I had not done.  Hooked it all up and then metered the test points on the new distro.  Ground was floating!  Checked the original distro and it was good.  Went to check the cams and the end came off the feeder cable!

I have no idea of how these connectors work, so please bear with me.  Just to clarify for me, are you stating the cam connector was still connected, but the wire had slipped out and was bare?
Is a simple yank on the wire/connector sufficient before connecting (by proper electrician).  If I owned the cables, what would be sufficient maintenance or test of these cables?
Title: Re: Just a reminder to check the power at your distro as well as the wall.
Post by: Tom Bourke on January 26, 2014, 03:31:43 pm
I have no idea of how these connectors work, so please bear with me.  Just to clarify for me, are you stating the cam connector was still connected, but the wire had slipped out and was bare?
Is a simple yank on the wire/connector sufficient before connecting (by proper electrician).  If I owned the cables, what would be sufficient maintenance or test of these cables?
Yes, the cable came out of the connector so I had a bare end of copper cable.  In this case it was a ground going to a distro with nothing on it yet so the danger was minimal.  However if I had not discovered it, then a failure of something else plugged into it could have caused a piece of equipment or even a metal support to become “live.”

As for a proper check, I should have given a tug on each end before mating it.  In use, a loose end on a current carrying line will cause heat at the connector.  The venue had one of the disconnects locked out because some one melted a line out of it.  I should have taken a pic. The scary part is that so much of the equipment we use is just rental and the people using it may not know any better.  Then when a problem is discovered it may or may not get marked.  If it is marked you can only hope the person who finds it in the shop does something about it.
Title: Re: Just a reminder to check the power at your distro as well as the wall.
Post by: Steve M Smith on January 26, 2014, 03:58:09 pm
I have no idea of how these connectors work

Neither do I.  If they are just a single conductor, how are they used?  And what prevents you from connecting them to the wrong place?

EDIT:  Just found this:
(http://www.jcustom.com/uploads/5/5/2/8/5528599/1346536863.jpg)

That seems like a crazy way to connect things.

We would use one of these:
(http://www.a1plantsales.com/images/products/medium/1363774265-43401100.jpg)


Steve.
Title: Re: Just a reminder to check the power at your distro as well as the wall.
Post by: Mike Sokol on January 26, 2014, 04:03:21 pm
Neither do I.  If they are just a single conductor, how are they used?  And what prevents you from connecting them to the wrong place?

EDIT:  Just found this: (http://www.jcustom.com/uploads/5/5/2/8/5528599/1346536863.jpg)

That seems like a crazy way to connect things.

Steve.

Yup, the colors are the only thing keeping you from making a mistake...

And NEVER pull the Neutral Cam while the circuit breaker is on and you're sending power to things. VERY BAD things will happen... I actually saw someone getting ready to do that on a gig to tie lighting into the third phase of a big generator, and I screamed and slapped his hand away.
Title: Re: Just a reminder to check the power at your distro as well as the wall.
Post by: Jerome Malsack on January 26, 2014, 04:40:14 pm
In the Navy we used Casualty power cables that were marked with color and texture. 

See note clipped. 

Casualty power terminals and casualty power cable conductors
are marked to identify (both by sight and by touch) the A, B, and C phases. Older-style casualty power cables
terminate at each end in individual conductors with copper ferrules. Rings of twine or 0-rings are applied over
the conductor insulation so that the phases can be identified by sight and touch. The A phase has one ring; the
B phase, two rings; and the C phase1 three rings. More recent casualty power cables are provided at each end
with a three-phase, keyed plug (a plug that can be plugged only into the proper phases of the casualty power
terminal).

The terminal also had the rings to indicate that your connecting the correct section of wire to the correct terminal connection. 
Title: Re: Just a reminder to check the power at your distro as well as the wall.
Post by: Tom Bourke on January 26, 2014, 07:19:54 pm
Neither do I.  If they are just a single conductor, how are they used?  And what prevents you from connecting them to the wrong place?

EDIT:  Just found this:
(http://www.jcustom.com/uploads/5/5/2/8/5528599/1346536863.jpg)

That seems like a crazy way to connect things.

We would use one of these:
(http://www.a1plantsales.com/images/products/medium/1363774265-43401100.jpg)


Steve.
I have seen those on gigs too.  The cams are for the next size or 2 up in current available.  Typically 400A lines.  Normally only specific people on the gig are allowed to make the connections. 
Title: Re: Just a reminder to check the power at your distro as well as the wall.
Post by: Lyle Williams on January 26, 2014, 08:12:39 pm
The problem with the multipin plugs is that there are so many different variants.
Title: Re: Just a reminder to check the power at your distro as well as the wall.
Post by: Jonathan Johnson on January 26, 2014, 08:22:23 pm
As for a proper check, I should have given a tug on each end before mating it.

Also applies to wire nuts. Whenever I install a wire nut, I tug on each of the wires individually to make sure they are secure. So many times a wire has pulled out... and I'm glad I gave it that tug.
Title: Re: Just a reminder to check the power at your distro as well as the wall.
Post by: Keith Broughton on January 27, 2014, 09:57:50 am
Neither do I.  If they are just a single conductor, how are they used?  And what prevents you from connecting them to the wrong place?

EDIT:  Just found this:
(http://www.jcustom.com/uploads/5/5/2/8/5528599/1346536863.jpg)

That seems like a crazy way to connect things.

We would use one of these:
(http://www.a1plantsales.com/images/products/medium/1363774265-43401100.jpg)


Steve.
I am seeing more configurations ( in Canada) with the ground and neutral the reverse connection genter to the 3 phases so it's more difficult to make a "hot / ground-neutral " swap error.
As for multi connectors, I have not seen one (as yet) that would do 400 amps per leg.
I'm sure they are available but would probably be expensive and a PITA!
Title: Re: Just a reminder to check the power at your distro as well as the wall.
Post by: Ray Aberle on January 27, 2014, 11:47:19 am
I am seeing more configurations ( in Canada) with the ground and neutral the reverse connection genter to the 3 phases so it's more difficult to make a "hot / ground-neutral " swap error.
As for multi connectors, I have not seen one (as yet) that would do 400 amps per leg.
I'm sure they are available but would probably be expensive and a PITA!
Plus the weight of the copper... I prefer single pole cams because 100' of #2 wire is easier to carry then 5x100' of #2 wire. :D OK, so I have to make five trips-- I still prefer to have home run lengths if possible, minimizing the connectors along the way (like if I, say, had 4-25' lengths of bundled #2, and had to connect all of them together...). Also minimizes the expense of buying lots of cam ends at $18-$25 each!

-Ray
Title: Re: Just a reminder to check the power at your distro as well as the wall.
Post by: Rob Spence on January 27, 2014, 11:54:35 am
Plus the weight of the copper... I prefer single pole cams because 100' of #2 wire is easier to carry then 5x100' of #2 wire. :D OK, so I have to make five trips-- I still prefer to have home run lengths if possible, minimizing the connectors along the way (like if I, say, had 4-25' lengths of bundled #2, and had to connect all of them together...). Also minimizes the expense of buying lots of cam ends at $18-$25 each!

-Ray

Not to mention that inspectors don't like to find many connectors in a single run.


Sent from my iPad using Tapatalk HD
Title: Re: Just a reminder to check the power at your distro as well as the wall.
Post by: Steve M Smith on January 27, 2014, 01:03:49 pm
I have seen those on gigs too.  The cams are for the next size or 2 up in current available.  Typically 400A lines.  Normally only specific people on the gig are allowed to make the connections.

The one in the picture is 415 volt, 32 amp.  There are 63 amp and 126 amp versions.

No restriction on who can plug them in here.  Not sure why there would be as it's just plugging something in, not connecting up bare wires.


Steve.
Title: Re: Just a reminder to check the power at your distro as well as the wall.
Post by: TJ (Tom) Cornish on January 27, 2014, 01:08:42 pm
The one in the picture is 415 volt, 32 amp.  There are 63 amp and 126 amp versions.

No restriction on who can plug them in here.  Not sure why there would be as it's just plugging something in, not connecting up bare wires.


Steve.
We don't have the luxury of 415v distribution, which is why we end up with 200A and 400A services as a matter of course.  Cams are more regulated than lesser-capacity means, as they can be more easily incorrectly connected (as well as partially connected) than a cord and plug connector.
Title: Re: Just a reminder to check the power at your distro as well as the wall.
Post by: Ray Aberle on January 27, 2014, 01:11:35 pm
Not to mention that inspectors don't like to find many connectors in a single run.


Sent from my iPad using Tapatalk HD
You just mentioned it!!

Plus there's the thought of voltage capacity of the feeder and lower rating for cable bundled as an SOOW cable (2/5 or whatever) as opposed to the single poles. I know people using 2/4 SOOW for their cam feed- not my preference, but eh, their choice.

-Ray
Title: Re: Just a reminder to check the power at your distro as well as the wall.
Post by: TJ (Tom) Cornish on January 27, 2014, 01:14:25 pm
Plus there's the thought of voltage capacity of the feeder and lower rating for cable bundled as an SOOW cable (2/5 or whatever) as opposed to the single poles. I know people using 2/4 SOOW for their cam feed- not my preference, but eh, their choice.

-Ray
It's their choice until the inspector chooses for them.  :)
Title: Re: Just a reminder to check the power at your distro as well as the wall.
Post by: Steve M Smith on January 27, 2014, 01:20:36 pm
It's their choice until the inspector chooses for them.

You have official inspections for plug and socket connections?

Are these Cam-Lok connectors a permanent fitting at the venue which you connect to or are they part of the distribution wiring you take to the venue and have wired in?

Most venues in the UK will have a three phase connection such as the one I posted a picture of. 


Steve.
Title: Re: Just a reminder to check the power at your distro as well as the wall.
Post by: TJ (Tom) Cornish on January 27, 2014, 01:28:10 pm
You have official inspections for plug and socket connections?

Are these Cam-Lok connectors a permanent fitting at the venue which you connect to or are they part of the distribution wiring you take to the venue and have wired in?

Most venues in the UK will have a three phase connection such as the one I posted a picture of. 


Steve.
Inspectors can show up whenever they feel like.  Frequently an inspection is triggered with a generator rental.  Many venues have a service connection with a lockable main switch with cam-loks - yes.  Typically the feeder cable and the downstream distro are carried by the production company.
Title: Re: Just a reminder to check the power at your distro as well as the wall.
Post by: Mike Sokol on January 27, 2014, 01:28:49 pm
You have official inspections for plug and socket connections?

Are these Cam-Lok connectors a permanent fitting at the venue which you connect to or are they part of the distribution wiring you take to the venue and have wired in?

Most venues in the UK will have a three phase connection such as the one I posted a picture of. 


Steve.

We traditionally have Cam-Loc connectors on a permanent, fused/CB disconnect in most venues for visiting acts. That's also how all our big rental generators are wired. Outside carnivals here use them for distro ride power as well.   
Title: Re: Just a reminder to check the power at your distro as well as the wall.
Post by: Tim McCulloch on January 27, 2014, 01:34:49 pm
You have official inspections for plug and socket connections?


Steve.

The essence is in Ray's post.  Using 2 AWG 4 conductor unitary jacketed cable with single pole, separable connectors (i.e. Cam Locks) is not permitted by NEC but that doesn't keep folks from doing so, at least until an inspector comes around.

Special events get inspected routinely, venues and facilities much less so, but in both cases an inspector may look at anything that catches his/her eye, everything, or almost nothing.  I had an inspector in Texas give me some grief about 2 SJO amp rack power cords (indoors, supported, off the floor) until I pointed out the county-owned facility had their Cam Lock tails "supported" from clamps rated for non-metalic sheathed cable (Romex).  He left to give the carnies a hard time.
Title: Re: Just a reminder to check the power at your distro as well as the wall.
Post by: Steve M Smith on January 27, 2014, 01:38:22 pm
I have just found something similar on a UK supplier's website, referred to as Power Lock so perhaps they are used here.

I have never come across them though.  Everyone I know uses the three phase connectors.  Perhaps they are used by the larger stadium and festival systems which I have no experience of.


Steve.
Title: Re: Just a reminder to check the power at your distro as well as the wall.
Post by: Tim McCulloch on January 27, 2014, 01:44:51 pm
I have just found something similar on a UK supplier's website, referred to as Power Lock so perhaps they are used here.

I have never come across them though.  Everyone I know uses the three phase connectors.  Perhaps they are used by the larger stadium and festival systems which I have no experience of.


Steve.

I've seen some big CEE-form connectors but don't recall seeing any rated for 400 amps, maybe 150 or so...  At any rate the purpose of any multi-pin connector scheme is to keep personnel from doing something dangerous by removing variables.  The higher voltage distribution in Europe allows a significant amount of energy to be connected more safely by a typical worker, via things like CEE-form.

You're probably right about Power Lock being used in much larger distribution systems and/or by "qualified persons only".
Title: Re: Just a reminder to check the power at your distro as well as the wall.
Post by: Ray Aberle on January 27, 2014, 01:56:59 pm
It's their choice until the inspector chooses for them.  :)

My "their choice" was aimed at the part of their decision making process to implement that 'solution' for their distro cabling.

The essence is in Ray's post.  Using 2 AWG 4 conductor unitary jacketed cable with single pole, separable connectors (i.e. Cam Locks) is not permitted by NEC but that doesn't keep folks from doing so, at least until an inspector comes around.
Pretty much what I meant to say as well. :) I can't make people do things the exact right way (cabling, pulling a permit for generator, having it inspected, etc)-- all I can do is make sure that everything I am involved with is abiding by the code. If a provider/client/whomever-calls-the-shots hasn't pulled a gennie permit, an inspector isn't going to come around since they don't know about it. If I am providing cam feeder for them, it'll be single conductor runs, you can be sure of that! (I am also anal about color and labeling. All new cam I build, I am ID tagging both ends with length and CompanyID#, so that I can always figure out which cable is going precisely where.)

-Ray
Title: Re: Just a reminder to check the power at your distro as well as the wall.
Post by: Steve M Smith on January 27, 2014, 02:01:55 pm
I've seen some big CEE-form connectors but don't recall seeing any rated for 400 amps, maybe 150 or so...

The biggest here is 125 amp. 415 volt three phase. 


Steve.
Title: Re: Just a reminder to check the power at your distro as well as the wall.
Post by: Jonathan Johnson on January 27, 2014, 04:44:20 pm
The one in the picture is 415 volt, 32 amp.  There are 63 amp and 126 amp versions.

No restriction on who can plug them in here.  Not sure why there would be as it's just plugging something in, not connecting up bare wires.

The potential that I see -- especially in higher-amperage connections -- is that someone would connect or disconnect the multipin power connector while the facility connection is energized and there is a load on the distro. That could result in a significant arc flash explosion.

Proper protocol is to remove loads from the distro AND disconnect power from the facility connection by moving the company switch to off before making or breaking connections. If a distro is 'loaded' (the loads have their power switches in the 'on' position) when the company switch is actuated, it can result in an arc in that switch. While the switch should be rated for interrupting its labeled current, arcs still wear on the switch and contribute to early failure. A failing company switch actuated under a heavy load could experience catastrophic failure.
Title: Re: Just a reminder to check the power at your distro as well as the wall.
Post by: Steve M Smith on January 27, 2014, 04:59:27 pm
The potential that I see -- especially in higher-amperage connections -- is that someone would connect or disconnect the multipin power connector while the facility connection is energized and there is a load on the distro. That could result in a significant arc flash explosion.

These are usually arranged so that the switch also locks the plug in place.  The last time I connected one up in a venue, this was the case.

The photo I linked to earlier was a panel mount type which would be part of your own distribution.  The venue's supply would have something like this:

(http://images.esellerpro.com/2272/I/221/906/PL0901105-40.jpg)

With this, you can only plug it in or remove it if the switch is off.  You can't even open the cover unless the switch is off.


Steve.
Title: Re: Just a reminder to check the power at your distro as well as the wall.
Post by: Ray Aberle on January 27, 2014, 05:42:20 pm
These are usually arranged so that the switch also locks the plug in place.  The last time I connected one up in a venue, this was the case.

The photo I linked to earlier was a panel mount type which would be part of your own distribution.  The venue's supply would have something like this:

(http://images.esellerpro.com/2272/I/221/906/PL0901105-40.jpg)

With this, you can only plug it in or remove it if the switch is off.  You can't even open the cover unless the switch is off.


Steve.
That's a good setup. Cams are not rated for interrupting current either, so same deal, you need to make sure the source is de-energized before connecting/removing the cables. And even still, ground (then neutral) connects first and removes last!

Ray
Title: Re: Just a reminder to check the power at your distro as well as the wall.
Post by: Tom Bourke on January 27, 2014, 05:43:49 pm
These are usually arranged so that the switch also locks the plug in place.  The last time I connected one up in a venue, this was the case.

The photo I linked to earlier was a panel mount type which would be part of your own distribution.  The venue's supply would have something like this:

(http://images.esellerpro.com/2272/I/221/906/PL0901105-40.jpg)

With this, you can only plug it in or remove it if the switch is off.  You can't even open the cover unless the switch is off.


Steve.
Do you still check your power with all these safety features?  I would think a lose or miswire is still possible. 
Title: Re: Just a reminder to check the power at your distro as well as the wall.
Post by: Jonathan Johnson on January 27, 2014, 06:31:27 pm
Do you still check your power with all these safety features?
Always inspect your safety features, test them where applicable, but never trust them.
Title: Re: Just a reminder to check the power at your distro as well as the wall.
Post by: Stephen Swaffer on January 27, 2014, 09:32:17 pm
Might be worth noting that in the example posted by Mike under arc flash, one of the serious violations cited by OSHA was failure to ensure that it was safe to apply power BEFORE energizing the circuit.   Certainly a missing ground and/or neutral would make it unsafe.  Just one more entity to encourage testing!

When I install a high energy circuit-a judgement call, but usually 60 A or greater-in an industrial situation, I usually use a megger/insulation tester to check for shorts to ground.  It is a quick test to make sure you don't energize a dead short and tempt a breaker to explode in your hand.  Just make sure with A/V stuff you are only testing distro and not equipment!
Title: Re: Just a reminder to check the power at your distro as well as the wall.
Post by: Steve M Smith on January 28, 2014, 01:52:06 am
Do you still check your power with all these safety features?  I would think a lose or miswire is still possible.

Yes, but obviously, a safety feature at the outlet doesn't prevent a problem further down the line.

A loose wire is possible whatever connectors you use but a hard wired plug isn't going to re-arrange itself in the way a set of single pole connectors could be miswired with just a colour code as a 'safety feature'.

And even still, ground (then neutral) connects first and removes last!

Every power connector in the UK, domestic or industrial, has the ground pin longer than the others so it always connects first and disconnects last.


Steve.
Title: Re: Just a reminder to check the power at your distro as well as the wall.
Post by: Tom Bourke on January 28, 2014, 02:24:10 am
Yes, but obviously, a safety feature at the outlet doesn't prevent a problem further down the line.

A loose wire is possible whatever connectors you use but a hard wired plug isn't going to re-arrange itself in the way a set of single pole connectors could be miswired with just a colour code as a 'safety feature'.

Every power connector in the UK, domestic or industrial, has the ground pin longer than the others so it always connects first and disconnects last.


Steve.
The reason I ask is that these threads tend to turn into comparisons to how much better or simpler power distribution is in Europe.  Often times implying “We couldn't possible have that problem here.” While I admit I envy the simpler standards, I think the main problems are the same.  I see far more problems from abuse and poor maintenance than confusion over plug type.  I am pretty sure bad maintenance happens, or dose not happen, on both sides of the pond.  Do you also have venues using odd or misusing connectors in an attempt to force you to buy power from them?
Title: Re: Just a reminder to check the power at your distro as well as the wall.
Post by: Steve M Smith on January 28, 2014, 02:46:05 am
Do you also have venues using odd or misusing connectors in an attempt to force you to buy power from them?

Buy power?  No.  We just turn up and plug in.

In the US you seem to have a lot of connectors to choose from.  Over here, it is very standardised.  Domestically, you will only find one type of outlet, the 13A socket, unless it is in a house which hasn't been upgraded in the last sixty years.  And in commercial and entertainment venues, you will always find the outlet I showed above.  These come in 32A, 63A (why not 64?) and 125A versions.

So yes, I think the siuation is better here.  Not in a smug "we're better than you" way but because you are in a bigger country which has had a lot more standards with regards to power connections over the years and your country tends to work with rules issued state by state whereas ours affect the country as a whole.

Standards of maintenance and attitudes to its importance are more to do with human nature than anything else and I'm sure we have our fair share of people whose standards are not good enough.


Steve.
Title: Re: Just a reminder to check the power at your distro as well as the wall.
Post by: Ray Aberle on January 28, 2014, 11:28:13 am
Buy power?  No.  We just turn up and plug in.

Steve.
Mostly hotels, but some venues, will utilize a specific wall outlet type (l5-15 or -20 are common), requiring renters to get the right adapter from the venue. By this method, the venue knows if you are using their power, and charges accordingly.

Even if there is no strange adapter, hotels will often charge for cam access. Another source of revenue, as it will make the general room charge seem smaller?

Ray
Title: Re: Just a reminder to check the power at your distro as well as the wall.
Post by: Jonathan Johnson on January 28, 2014, 06:40:37 pm
A loose wire is possible whatever connectors you use but a hard wired plug isn't going to re-arrange itself in the way a set of single pole connectors could be miswired with just a colour code as a 'safety feature'.

Such as might occur in a low-light or colored-light situation. Under green lights, red and black will be difficult to distinguish, as will green and white. Under red light, it's green/black and red/white -- a potentially more dangerous mixup. Under other colors, it could be any kind of mixup. Bottom line:  only make connections under white light that is sufficient to do the job safely.
Title: Re: Just a reminder to check the power at your distro as well as the wall.
Post by: frank kayser on January 28, 2014, 07:12:30 pm
Such as might occur in a low-light or colored-light situation. Under green lights, red and black will be difficult to distinguish, as will green and white. Under red light, it's green/black and red/white -- a potentially more dangerous mixup. Under other colors, it could be any kind of mixup. Bottom line:  only make connections under white light that is sufficient to do the job safely.

That does beg the question - why can a red lead be plugged into a white socket?
Why can't the cams be keyed such that the one color plug fits into only its respective colored socket?
Or at least use a molded in identification ring as being done aboard ship? somewhere earlier in the thread

I know there is a huge installed base, and it is easy for the manufactures of the cams to have one mold, and just swap out the plastic colors in the injection molding machine.

I have heard that (please correct me) the genders on the safety ground and neutral are sometimes changed so as to prevent the ground neutral miswiring.

 
Title: Re: Just a reminder to check the power at your distro as well as the wall.
Post by: Rob Spence on January 28, 2014, 07:14:15 pm
Mostly hotels, but some venues, will utilize a specific wall outlet type (l5-15 or -20 are common), requiring renters to get the right adapter from the venue. By this method, the venue knows if you are using their power, and charges accordingly.

Even if there is no strange adapter, hotels will often charge for cam access. Another source of revenue, as it will make the general room charge seem smaller?

Ray
Around here I see 14-60 connectors in ballroom kick plates. They use them for the distros they rent to you.  I have my own :-)


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Title: Re: Just a reminder to check the power at your distro as well as the wall.
Post by: Tim McCulloch on January 28, 2014, 08:21:12 pm
That does beg the question - why can a red lead be plugged into a white socket?
Why can't the cams be keyed such that the one color plug fits into only its respective colored socket?
Or at least use a molded in identification ring as being done aboard ship? somewhere earlier in the thread

I know there is a huge installed base, and it is easy for the manufactures of the cams to have one mold, and just swap out the plastic colors in the injection molding machine.

I have heard that (please correct me) the genders on the safety ground and neutral are sometimes changed so as to prevent the ground neutral miswiring.

The keyed version of CamLocks are called Posi-Locks and are nearly universally ignored in the touring entertainment world, at least on the load side of the switch.  Our county's arena has them and had to make up adapters to conventional e1016 Cams.  The only folks that seem to use them in touring are the generator suppliers, and then predominantly of the 480v side.

Although not required by NEC itself, the reversed gender of Ground (earth) and Neutral (grounded, current-carrying conductor) is required in some jurisdictions.  Mechanical interlocks, keyed connectors, reversed genders, or simply posting the required connection order on each panel or device equipped with single pole separable connectors are all permitted by the NEC and considered compliant.  Note that individual jurisdictions (city, county, state) are free to adopt, ignore, or modify the NEC as they see fit.
Title: Re: Just a reminder to check the power at your distro as well as the wall.
Post by: frank kayser on January 28, 2014, 08:59:25 pm
The keyed version of CamLocks are called Posi-Locks and are nearly universally ignored in the touring entertainment world, at least on the load side of the switch.  Our county's arena has them and had to make up adapters to conventional e1016 Cams.  The only folks that seem to use them in touring are the generator suppliers, and then predominantly of the 480v side.

I guess the Posi-Locks are considered a solution looking for a problem.  I suspect they would be more popular and catch on if they were backwards compatible with the CamLocks.

Dang. Another "original idea" of mine tried and rejected.  Yeah.  Right.
frank
Title: Re: Just a reminder to check the power at your distro as well as the wall.
Post by: TJ (Tom) Cornish on January 29, 2014, 08:41:21 am
Around here I see 14-60 connectors in ballroom kick plates. They use them for the distros they rent to you.  I have my own :-)


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Me too.  :)

There's one hotel in the city that uses a 15-60 (3-phase with no neutral, so N-G bond in the distro panel), and MANY hotels doing some version of way-overloaded breakout distros - 100A on #4 wire, etc.  Loads of fun.
Title: Re: Just a reminder to check the power at your distro as well as the wall.
Post by: Chris Hindle on January 29, 2014, 08:42:43 am
I guess the Posi-Locks are considered a solution looking for a problem.  I suspect they would be more popular and catch on if they were backwards compatible with the CamLocks.

If they were backwards compatible with cams, what would be the point ??
You would negate the safety aspect of the Posi-Locks.
note - I have not seen a Posi-Lock in the wild, only at the electrical supplier.
note2 - I don't get around as much as I used to....
Title: Re: Just a reminder to check the power at your distro as well as the wall.
Post by: frank kayser on January 29, 2014, 09:29:48 am
If they were backwards compatible with cams, what would be the point ??
You would negate the safety aspect of the Posi-Locks.
note - I have not seen a Posi-Lock in the wild, only at the electrical supplier.
note2 - I don't get around as much as I used to....

My thought of PosiLocks backward compatable - I agree - at first there would be no benefit.  But if the NEC were to "suggest" that all new panel installations or upgrades use the new connector, then there would be a gradual replacement of all the cable-installed CamLocks (rather than a large, immediate,expensive changeover).  In a couple years, all stuff will have gone through a life cycle, and replaced with the keyed connectors.

As it stands, they are nothing more than a pain for which Tim and others have to make adapters for the very few installations found.  Unlikely you will see many in the wild unless mandated by code, which will be strongly resisted because of the cost of changeover.  Tim mentioned he has only seen them occasionally in his county, and they seem to have caught on with the gen set crowd on the 480v side. 

I could see where the gen set folks would use them - less mistakes by lesser qualified "installers", and many times they also provide their own distro.  The gen sets and cable sets are turned over surely more often than folks rewire installed panels.  An attempt to make things idiot resistant.
Title: Re: Just a reminder to check the power at your distro as well as the wall.
Post by: Chris Hindle on January 29, 2014, 12:36:48 pm
In a couple years, all stuff will have gone through a life cycle, and replaced with the keyed connectors.
You're kidding, right ??
Life Cycle on a cam is much longer than a couple of years. I think I bought my first set around 1980.
I am the only one that handles them, and all they need is a little yearly cleanup/checkup.
I have seen some pretty questionable "company switches" over the years, but with a little extra twist or 2, the cams have held just fine.
No, you're right. Mandated change is the only way to weed out the old shit, without taking the next 25 years....
Title: Re: Just a reminder to check the power at your distro as well as the wall.
Post by: Tom Bourke on January 29, 2014, 01:16:00 pm
Me too.  :)

There's one hotel in the city that uses a 15-60 (3-phase with no neutral, so N-G bond in the distro panel), and MANY hotels doing some version of way-overloaded breakout distros - 100A on #4 wire, etc.  Loads of fun.
I have also seen 3 phase plugs wired like the single phase counterpart.  Anything to keep you from using it with out paying the piper.
Title: Re: Just a reminder to check the power at your distro as well as the wall.
Post by: Chris Clark on January 29, 2014, 04:31:47 pm
I have heard that (please correct me) the genders on the safety ground and neutral are sometimes changed so as to prevent the ground neutral miswiring.
That is true:
When I was working for a now-defunct production company in the area, our 2/0 and 4/0 feeder looms (5 cables taped together, let me tell you that was fun running across a hotel!) which used cams had the green/white reversed at all times. This matched our power distros which were setup the same way, and the pigtails which were used for tie-in when necessary were also typically in sets of this configuration. The problem was that when using a genny for productions, or existing tie-ins already at some locations, we typically had to have turnarounds (sometimes known as gender benders) for them. But even with that, it helped immensely to ensure that the possibility of messing up the neutral/ground with one of the hot legs was kept to a minimum. Not to mention it was policy that any wiring of that nature was double or sometimes triple checked by others, typically the gig boss and/or the lead sound or lighting guy (one of which was usually the gig boss anyway), both of whom had final say before any switches were thrown or generators powered up. As a hired hand, if you violated this (powered up the genny on your own before checking with the gig boss, for example, which happened once) you were pretty much thrown off the site. Only the gig boss or leads were allowed to meter the power at the disconnect/genny, throw on the disconnect after checking that the distro power was off, meter the power at the distro, and then turn on the distros, and again this was after it had been checked by them visually. Sometimes the procedures seem long and drawn out, but they work.
Title: Re: Just a reminder to check the power at your distro as well as the wall.
Post by: Steve M Smith on January 30, 2014, 01:56:14 am
Sometimes the procedures seem long and drawn out, but they work.

As does the simple method of having all the conductors in one connector.


Steve.
Title: Re: Just a reminder to check the power at your distro as well as the wall.
Post by: Chris Clark on January 30, 2014, 02:52:41 am
No argument against that here, Steve. Not my fault my country has a perverted sense of complexity with regards to our electrical system (277/480 3ph, 120/208 3ph, 120/240 split, 208 high leg... the list goes on) and more connector options than a 1990's computer.

That being said, I can only imagine how large an all-in-one connector that is rated for 400A would be. (I honestly don't know, I've never really looked since cams are all I've ever been exposed to with that kind of rating)
Title: Re: Just a reminder to check the power at your distro as well as the wall.
Post by: Steve M Smith on January 30, 2014, 04:54:59 am
That being said, I can only imagine how large an all-in-one connector that is rated for 400A would be.

That's where we have the advantage.  Twice the voltage means we can halve the current.  Although our largest three phase connector is 125A (as far as I know).  No harm having more than one though - and any plug can go into any socket it fits with no problems.


Steve.
Title: Re: Just a reminder to check the power at your distro as well as the wall.
Post by: Mike Sokol on January 30, 2014, 08:28:40 am
Not my fault my country has a perverted sense of complexity with regards to our electrical system (277/480 3ph, 120/208 3ph, 120/240 split, 208 high leg... the list goes on) and more connector options than a 1990's computer.

Since I'm a bit of a student of history (my dad was an American History teacher) I think we need to examine the history of power in each country to see why the US system seems/is so crazy. Basically electrical power transmission systems were developed in the United States by Edison and Tesla/Westinghouse in the late 1800's and early 1900's. There was a bitter battle between AC and DC power at the time, with AC originally starting as 25 Hz / 2-phase then eventually changing to 60 Hz / 3-phase. Even though AC power distribution eventually won out, there were still parts of New York City being powered by DC until the 1990's and 25 Hz was still around even in the 80's around Niagra Falls. So American has had a continuous experiment/upgrade of our power distribution system for the last 120 years without interruption. Add to this the fact that our National Electrical Code is not a national law, and each state can choose to accept or reject any part of it. We also have history of "grandfathering" existing wiring, with the result that my own house still has a lot of K&T (knob & tube) wiring from the 1920, which I'm replacing as we renovate each room. That upgrade is a personal choice by me, but is not required by any local/state/country code inspection.

European countries have more uniform power distribution (at least from what I have read) perhaps because many of them had their power and transportation infrastructures destroyed in WWII and rebuilt in the 1950's. So much of European power distribution is less than 60 years old, plus it appears you have more uniform power legislation across each country without our USA separate state/county/city regulation divisions.

Now things aren't more uniform or better in all countries. I get a lot of emails from India and there seems to be all kinds of dangerous and non-standard power practices there. And I'm sure there's other countries with way-different power generation and distribution I've never heard about. At last count my NoShockZone.org articles have been downloaded and read in 70+ countries, but I have no idea what kind of electrical power is generated or how it's distributed in all those countries. 

So let's not beat up on the poor USA too much. After all, we are where Edison and Tesla and Westinghouse (any many hundreds of others) figured out how to generate and transmit electrical power, which helped change the world. And as long as you can use a voltmeter, it's still a safe system in the USA. However, the new smart grid and electric cars are coming soon, and then it's going to get REALLY interesting here.
Title: Re: Just a reminder to check the power at your distro as well as the wall.
Post by: TJ (Tom) Cornish on January 30, 2014, 08:52:50 am
Since I'm a bit of a student of history (my dad was an American History teacher) I think we need to examine the history of power in each country to see why the US system seems/is so crazy. Basically electrical power transmission systems were developed in the United States by Edison and Tesla/Westinghouse in the late 1800's and early 1900's. There was a bitter battle between AC and DC power at the time, with AC originally starting as 25 Hz / 2-phase then eventually changing to 60 Hz / 3-phase. Even though AC power distribution eventually won out, there were still parts of New York City being powered by DC until the 1990's and 25 Hz was still around even in the 80's around Niagra Falls. So American has had a continuous experiment/upgrade of our power distribution system for the last 120 years without interruption. Add to this the fact that our National Electrical Code is not a national law, and each state can choose to accept or reject any part of it. We also have history of "grandfathering" existing wiring, with the result that my own house still has a lot of K&T (knob & tube) wiring from the 1920, which I'm replacing as we renovate each room. That upgrade is a personal choice by me, but is not required by any local/state/country code inspection.

European countries have more uniform power distribution (at least from what I have read) perhaps because many of them had their power and transportation infrastructures destroyed in WWII and rebuilt in the 1950's. So much of European power distribution is less than 60 years old, plus it appears you have more uniform power legislation across each country without our USA separate state/county/city regulation divisions.

Now things aren't more uniform or better in all countries. I get a lot of emails from India and there seems to be all kinds of dangerous and non-standard power practices there. And I'm sure there's other countries with way-different power generation and distribution I've never heard about. At last count my NoShockZone.org articles have been downloaded and read in 70+ countries, but I have no idea what kind of electrical power is generated or how it's distributed in all those countries. 

So let's not beat up on the poor USA too much. After all, we are where Edison and Tesla and Westinghouse (any many hundreds of others) figured out how to generate and transmit electrical power, which helped change the world. And as long as you can use a voltmeter, it's still a safe system in the USA. However, the new smart grid and electric cars are coming soon, and then it's going to get REALLY interesting here.
I agree - it's not so bad here, assuming people follow the code and don't do intentional mis-wires like a few hotels do to "customize" their PD.  We have 60Hz, which is generally better than 50Hz, and the 120V standard wasn't arrived at arbitrarily, but was deemed a good compromise between power capacity and safety.  There are some circumstances in the UK (construction industry) where new laws are actually mandating 120V power tools since they are safer than 240V tools.   Tradesman have to bring a 240->120V transformer to the jobsite.

It's amazing how young a technology electricity is.  There are surely growing pains, but it's getting better.  Putting my Popular Mechanics hat on - it will be interesting to see how pervasive electric cars become, and how that weighs against efficiency gains in lighting and computing on the grid.  I'd love to see Thorium-based power plants go online to actually power all this new cool stuff.
Title: Re: Just a reminder to check the power at your distro as well as the wall.
Post by: Steve M Smith on January 30, 2014, 11:08:59 am
There are some circumstances in the UK (construction industry) where new laws are actually mandating 120V power tools since they are safer than 240V tools.

It's not new.  110 volt power tools have been standard on building sites for at least the last thirty years.  Not only are they safer due to the low voltage but they are also grounded on a centre tap so there is only 55 volts relative to ground.


Steve.
Title: Re: Just a reminder to check the power at your distro as well as the wall.
Post by: Mike Sokol on January 30, 2014, 11:18:19 am
I agree - it's not so bad here, assuming people follow the code and don't do intentional mis-wires like a few hotels do to "customize" their PD.

Here's one example of how two different sub-industries in the USA created outlet confusion. In the 60's there were a lot of 240-volt/3-wire electric stove and dryer outlets installed without a separate neutral and ground. Then in the 70's (I think) the Recreational Vehicle industry came out with their TT-30 receptacle wired for 120-volts at 30-amps, but looking very similar to a old 240-volt/30-amp dryer outlets. I get dozens of emails every year from RV owners who hire an electrician to wire up a dedicated TT-30 (120-volt/30-amp) outlet in their garage to plug in their RV. However, there are some electricians who don't understand it's supposed to be 120-volts, and they wire it up to 240-volts instead. The unsuspecting RV owner then plugs his 120-volt RV into 240-volts, and does 10's of thousand of dollars in damage in just a few seconds. See my NoShockZone article about it at http://www.noshockzone.org/accidentally-plugging-into-240-volt-outlet/
 
Title: Re: Just a reminder to check the power at your distro as well as the wall.
Post by: Stephen Swaffer on January 30, 2014, 01:59:27 pm
I had a family member in an apprenticeship program tell me over the holidays that one of his teachers who is involved in the power distribution industry told them they are now experimenting with DC distribution on ultra high voltage distribution lines to minimize impedance losses.  Third hand info, so don't beat up too much on details-but if that is true, sounds like things are still evolving and we may have come full circle.

I am seeing a lot of K & T and fuse boxes being upgraded either during a home ownership transfer, or by insurance company mandate.  That is my personal preference over government mandate-and seems to avoid hardships on owners.

As for industry confusion, I installed a new dryer Monday.  Their instructions said to connect the "neutral ground".  What does that mean?!
Title: Re: Just a reminder to check the power at your distro as well as the wall.
Post by: Mike Sokol on January 30, 2014, 02:51:13 pm
As for industry confusion, I installed a new dryer Monday.  Their instructions said to connect the "neutral ground".  What does that mean?!

I actually know exactly what that means and it's relevant to pro-audio distributed power in small clubs. Do you want me to write up a short primer on the subject?                                 
Title: Re: Just a reminder to check the power at your distro as well as the wall.
Post by: Jonathan Johnson on January 30, 2014, 03:10:07 pm
I had a family member in an apprenticeship program tell me over the holidays that one of his teachers who is involved in the power distribution industry told them they are now experimenting with DC distribution on ultra high voltage distribution lines to minimize impedance losses.  Third hand info, so don't beat up too much on details-but if that is true, sounds like things are still evolving and we may have come full circle.

There has been a megavolt (+/- 500kV pole-ground) DC transmission line between The Dalles, Oregon and Sylmar, California since about 1970. http://en.wikipedia.org/wiki/Pacific_DC_Intertie (http://en.wikipedia.org/wiki/Pacific_DC_Intertie)

As for industry confusion, I installed a new dryer Monday.  Their instructions said to connect the "neutral ground".  What does that mean?!

I don't know what that means either, because it's an invalid term but I hope Mike will enlighten us.  :)

Ideally, you will use a 4-wire cordset on the dryer with a NEMA 14-30 plug, connecting into a NEMA 14-30 receptacle. On the terminal block of the dryer there will be a jumper to connect between the neutral terminal and the chassis of the dryer. Remove this jumper.

If, on the other hand, you have a 3-wire NEMA 10-30 receptacle, check to see if there are separate ground and neutral conductors in the receptacle box. If so, replace the 10-30 with a 14-30.

If replacing the receptacle is not an option, then you'll have to use a 3-wire cordset with a 10-30 plug. In that case, you will connect the jumper between chassis and neutral. This, along with kitchen ranges, is the ONLY acceptable bootleg ground anymore, and then ONLY if the receptacle cannot easily be replaced with a NEMA 14-30.

(http://upload.wikimedia.org/wikipedia/commons/0/0d/NEMA_simplified_pins.svg)

This diagram is not comprehensive.
Title: Re: Just a reminder to check the power at your distro as well as the wall.
Post by: Steve M Smith on January 30, 2014, 04:42:32 pm
This diagram is not comprehensive.

Really?  Here is the diagram showing all of the UK domestic outlets:
(http://www.discount-electrical.co.uk/shopimages/sections/normal/domestic_wiring/CED/CED_cedssk2.jpg)

The rating is determined by the fuse in the plug rather than having a different plug and socket set for each rating.  3A, 5A or 13A.

(http://www.everydayhowto.net/wp-content/uploads/2009/05/plug11.jpg)  (http://www.astra247.com/ProductImages/7705.jpg)

And you might find this one in bathrooms.  Transformer isolated for electric razors:
(http://www.discount-electrical.co.uk/shopimages/products/normal/domestic_wiring/Legrand/LEG_730090.jpg)

And very rarely, this one for electric clocks:
(http://www.electrical-contractor.net/PC/ClockConn2.jpg)

I have only ever seen one of these and that was in my grandfather's house about thirty years ago.


Steve.
Title: Re: Just a reminder to check the power at your distro as well as the wall.
Post by: Rob Spence on January 30, 2014, 04:46:38 pm
There has been a megavolt (+/- 500kV pole-ground) DC transmission line between The Dalles, Oregon and Sylmar, California since about 1970. http://en.wikipedia.org/wiki/Pacific_DC_Intertie (http://en.wikipedia.org/wiki/Pacific_DC_Intertie)


We have a million volt DC (+ & - 500kv) line here from Ayer to somewhere in Quebec. It has been in service for >20 years.

Sent from my iPad using Tapatalk HD
Title: Re: Just a reminder to check the power at your distro as well as the wall.
Post by: TJ (Tom) Cornish on January 30, 2014, 04:48:58 pm

Really?  Here is the diagram showing all of the UK domestic outlets:
The chart Jonathan posted covers FAR more than "domestic" receptacles.  For domestic receptacles in the same general usage case as what you show, we have basically two compatible versions of the same thing (clipped from the Wiki picture Jonathan used).  The others are special-purpose, and many are more analogous to your industrial Cee-forms.

Title: Re: Just a reminder to check the power at your distro as well as the wall.
Post by: Jonathan Johnson on January 30, 2014, 05:34:48 pm
The chart Jonathan posted covers FAR more than "domestic" receptacles.

Yes, there is a bewildering array of connector form factors in common use here in the United States, and that doesn't include the even larger array of now-obsolete connectors. For example, a receptacle with prongs in a crowsfoot layout (similar to NEMA 10-50 but the same size as NEMA 5-15) was listed for either 120V or 240V at 20 amps. These were typically used with large space heaters. There's an opportunity for disaster -- one could assume that a receptacle is 120V when it's really 240V. Thankfully, those obsolete plugs are no longer acceptable to the electrical codes, BUT they are still available for "repairs."

As a rule-of-thumb, the first number in a NEMA designation refers to a general physical size & prong placement, while the second number is the amperage rating.

In residential wiring, you will generally only see NEMA 5-15 receptacles (120V, 15A) for small appliances. NEMA 5-15 receptacles may be used on 20A circuits, though the connected load is not to exceed 15A -- which may be enforced by a circuit breaker in power strips. (It's rare to see a fused plug in the U.S.) That means that a multi-tap cord or adapter block without a breaker could potentially be overloaded, as could an ordinary extension cord, since most of the cords marketed to consumers are only 16 AWG (1.29mm). NEMA 5-15 receptacles may also appear in commercial installs.

NEMA 5-20 receptacles (120V 20A, compatible with NEMA 5-15 plugs) are usually only seen in commercial installations where there is potential for connected loads requiring more than 15 amps, though they may be installed in some residences. There is nothing to stop you from using a 16-gauge unfused extension cord on a 20A receptacle and overloading the cord.

NEMA 10-30, 10-50, 14-30, and 14-50 receptacles are usually only seen for clothes dryers (120/240V 30A) and kitchen ranges (120/240V 50A). As has been covered before, NEMA 10-30 and 10-50 implies that a bootleg ground will be present.

You might see a NEMA 6-15 or 6-20 receptacle (240V, 15A or 20A) used for a large window or through-wall air conditioner.

Other than that, the rest of those connectors will usually only be seen in commercial installations or large home workshops.

*****

To confuse the American consumer even more, for a given receptacle type (for example, NEMA 5-15) there are a number of different features: basic (read: cheap, <$1.00), "Pro" grade (slightly better than basic), "Spec" grade (meets military specifications), Isolated ground, hospital grade, tamper resistant, etc. And then there are Hubbell brand receptacles, which are overbuilt and nearly indestructible, but are also relatively expensive (~$10.00).
Title: Re: Just a reminder to check the power at your distro as well as the wall.
Post by: Steve M Smith on January 30, 2014, 06:14:34 pm
(It's rare to see a fused plug in the U.S.) That means that a multi-tap cord or adapter block without a breaker could potentially be overloaded, as could an ordinary extension cord

The advantage with having the fuse in the plug is that you can't overload anything (well, only until the fuse blows).

Our standard multi way extension lead/adaptor looks like this:
(http://www.delightful-uk.com/ekmps/shops/kennedyelec/images/extension-lead.-heavy-duty-switched-4-way-4m-cable-13a-with-fuse-neon-2842-p.jpg)

You could plug lots of these together to connect hundreds of appliances but they would all be drawing current from one plug.  And that plug will have a 13 amp fuse in it so the supply circuit cannot be overloaded (unless you replace the fuse with a piece of 1/4" rod!).


Steve.
Title: Re: Just a reminder to check the power at your distro as well as the wall.
Post by: Stephen Swaffer on January 30, 2014, 08:39:20 pm
Jonathan,

I knew how to wire the dryer-whether 3 wire or 4 wire without the manual; however, I was trying to use the project to teach a little to my 17 yr old son.  When he wasn't sure how to wire, my first thought was to hand him the manual  (I'd rather he learn how to figure out how to do something than just how to do it).  I glanced at it first, expecting to see "pic A, 3 wire hookup, pic b 4-wire".  Instead, there were 2 pages using oddball terms like "neutral ground".  Honestly, "white wire with ring terminal" would have been more descriptive and more easily understood by most people, and arguably no less accurate.  But then I suppose the author did not grow up building Heathkits!

I would like to see Mike's explanation, though.

Maybe those familiar with the DC distribution can answer a nagging question I have about it.  What technology is used for rectification and for converting back to AC?  Inverters are common these days, but high voltage is not solid state's strongpoint?
Title: Re: Just a reminder to check the power at your distro as well as the wall.
Post by: Rob Spence on January 30, 2014, 08:45:35 pm
Don't forget the (now) common L14-30 found on so many home portable generators.
Funny how the "L14-" is so different in size and shape than the "14-" connectors.

Sent from my iPad using Tapatalk HD
Title: Re: Just a reminder to check the power at your distro as well as the wall.
Post by: Jonathan Johnson on January 30, 2014, 09:02:02 pm
Maybe those familiar with the DC distribution can answer a nagging question I have about it.  What technology is used for rectification and for converting back to AC?  Inverters are common these days, but high voltage is not solid state's strongpoint?

I really don't know much about the technology. Conversion to DC is done at the Celilo Converter Station (http://en.wikipedia.org/wiki/Celilo_Converter_Station) in The Dalles, Oregon, and conversion back to AC is done at the Sylmar Converter Station (http://en.wikipedia.org/wiki/Sylmar_Converter_Station) in Sylmar, California.

It seems to me that the conversion back to AC would be akin to a very, very big audio amplifier. Provide it high voltage, high current DC power, give it a 60Hz sine wave as "input" and output high voltage, high current AC power.
Title: Re: Just a reminder to check the power at your distro as well as the wall.
Post by: TJ (Tom) Cornish on January 30, 2014, 09:04:25 pm
I really don't know much about the technology. Conversion to DC is done at the Celilo Converter Station (http://en.wikipedia.org/wiki/Celilo_Converter_Station) in The Dalles, Oregon, and conversion back to AC is done at the Sylmar Converter Station (http://en.wikipedia.org/wiki/Sylmar_Converter_Station) in Sylmar, California.

It seems to me that the conversion back to AC would be akin to a very, very big audio amplifier. Provide it high voltage, high current DC power, give it a 60Hz sine wave as "input" and output high voltage, high current AC power.
it used to be done in huge mercury rectifier tubes. There are You Tube videos that show these. I assume it is done via solid state tech now, but haven't seen anything about that.
Title: Re: Just a reminder to check the power at your distro as well as the wall.
Post by: Jonathan Johnson on January 30, 2014, 09:07:17 pm
it used to be done in huge mercury rectifier tubes. There are You Tube videos that show these. I assume it is done via solid state tech now, but haven't seen anything about that.
The inline links in my previous post link to relevant Wikipedia articles. They indicate that thyristors are now used in place of the mercury tubes.
Title: Re: Just a reminder to check the power at your distro as well as the wall.
Post by: Tom Bourke on January 31, 2014, 12:25:06 am
And now to pull it back on topic.  Here is what happens if you run with loose connectors:
Title: Re: Just a reminder to check the power at your distro as well as the wall.
Post by: Tommy Peel on January 31, 2014, 01:36:01 am
I really don't know much about the technology. Conversion to DC is done at the Celilo Converter Station (http://en.wikipedia.org/wiki/Celilo_Converter_Station) in The Dalles, Oregon, and conversion back to AC is done at the Sylmar Converter Station (http://en.wikipedia.org/wiki/Sylmar_Converter_Station) in Sylmar, California.

It seems to me that the conversion back to AC would be akin to a very, very big audio amplifier. Provide it high voltage, high current DC power, give it a 60Hz sine wave as "input" and output high voltage, high current AC power.

Interesting read. Here's a video of one of those Mercury rectifiers btw:

 https://www.youtube.com/watch?v=q89SV_UwykQ&feature=youtube_gdata_player  (https://www.youtube.com/watch?v=q89SV_UwykQ&feature=youtube_gdata_player)

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