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Author Topic: Right or Wrong? New building has receptacles with Hot and Neutral reversed.  (Read 7819 times)

frank kayser

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Re: Right or Wrong? New building has receptacles with Hot and Neutral reversed.
« Reply #20 on: September 20, 2017, 03:18:41 pm »

I was in disbelief. Therefore , I did verify the Extech CT80 tester at home after the show and 30 seconds ago on my current show. It works as it should. Also, on the show that day I use 12ga SJ cables with an outlet tester that's integrated into the Edison connector. They usually glow green when all is good and red when something is wrong. On this day the green and red LED's were on simultaneously on all 4 of them regardless of where I plugged them in. I have never seen that.


Are you using the Legrand/Pass and Seymour GCM plug/cord-receptacle devices? https://www.legrand.us/search.aspx?q=GCM
I have them on all my cords, which provides a "canary in the coal mine test" of anything I plug into.  Not that those devices should be used exclusively, but if the Extech reads fail and all the GCM devices are either blank or showing a red indicator, you have a pretty reliable indication something is definitely wrong.  The NCVT test as a third test should remove any and all doubt something is amiss.


Is it safe (enough)?
After confirming a confirmation of an indication that there is a problem, but no RPBG, should the show go on?  Would that be a reason to load the gear back on the truck?  Does anyone have a contract clause that defines actions should the power prove unsuitable or unsafe?


Temporary fix to make it safer (or not)
If one had an "adapter" that reverses neutral and ground, would the stage be safer?  If there were any RPBG on any of the downstream wall receptacles, would that not cause a direct short and pop the breaker?  Arc flash an issue?

Edited due to mind-finger malfunction and general stupidity...

When do we stop when electric tests good?
On a tangent, If the Extech says all is OK, is it safe?  How about with a solid green only indication on the GCM device in addition to the Extech?  Is that safe?  Should one's test always use a three-tester test? 


Granted, neither the Extech nor the GCM devices will actually identify a RPBG condition, apart or together.  if you used the Extech, and all/any of the cords one has made up has an GCM device, there is an automatic second-level test.  Can there be a possibility of a RPBG if there is no indicated reverse polarity, and the ground shows voltage within expected ranges on the Extech?  Would that preclude the actual test with the NCVT?   


I will grant the NCVT is so quick, easy, and positive this question is more a technicality than a practical matter.

« Last Edit: September 20, 2017, 08:25:05 pm by frank kayser »
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Stephen Swaffer

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Re: Right or Wrong? New building has receptacles with Hot and Neutral reversed.
« Reply #21 on: September 20, 2017, 04:44:25 pm »


A

Temporary fix to make it safer (or not)
If one had an "adapter" that reverses neutral and ground, would the stage be safer?  If there were any RPBG on any of the downstream wall receptacles, would that not cause a direct short and pop the breaker?  Arc flash an issue?



For me RPBG is a deal breaker-and no way I am gonna have an adapter laying around to fix that-that's a hazard in itself.

Reversed polarity?  Depending on gear and setup.  Obviously, first look for an alternative-however in most modern gear polarity is not an issue-nor really is voltage if something is happy from 90-240 volts.

IMO, polarity is really more of an issue for the electrician's-once they leave leve they have no control over what is plugged in there and if someone plugs in an Eico tube amp like the one I used to run on a metal bookshelf in my room as a teen that has it's chassis tied to one side of the line that can get ugly. If you know and are aware and can control what is plugged in, honestly you are probably OK.  Again, really don't like the idea of an adapter unless it is kept under lock and key for teaching purposes only!
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John Roberts {JR}

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Re: Right or Wrong? New building has receptacles with Hot and Neutral reversed.
« Reply #22 on: September 20, 2017, 05:01:11 pm »


Are you using the Legrand/Pass and Seymour GCM plug/cord-receptacle devices? https://www.legrand.us/search.aspx?q=GCM
I have them on all my cords, which provides a "canary in the coal mine test" of anything I plug into.
If these use similar technology to 3 lamp testers, they may have similar vulnerabilities.
Quote
Not that those devices should be used exclusively, but if the Extech reads fail and all the GCM devices are either blank or showing a red indicator, you have a pretty reliable indication something is definitely wrong.
probably
Quote
The NCVT test as a third test should remove any and all doubt something is amiss.
NCVT is the holy grail for hazardous voltages, at least more professional NCVT than mine.  If the chassis ground is hot, DO NOT TOUCH. Back away slowly.
Quote

Is it safe (enough)?
After confirming a confirmation of an indication that there is a problem,
I am probably repeating myself but swapped line-neutral with a good safety ground is wrong, but not a safety hazard for users. Whomever is in charge of the venue needs to be informed so he can jack up his electricians but the show can go on.
Quote
but no RPBG, should the show go on? 
yes
Quote
Would that be a reason to load the gear back on the truck?  Does anyone have a contract clause that defines actions should the power prove unsuitable or unsafe?
RPBG is a show stopper, swapped line-neutral not so much.
Quote

Temporary fix to make it safer (or not)
If one had an "adapter" that reverses neutral and ground, would the stage be safer?
no and that adapter sounds like an accident waiting to happen.
Quote
If there were any RPBG on any of the downstream wall receptacles, would that not cause a direct short and pop the breaker?  Arc flash an issue?
swapped line and neutral is the RP of RPBG, so a bootleg ground in combination with the reversed polarity is the grim reapers parley.
Quote

When do we stop when electric tests good?
um when the tests are good?
Quote
On a tangent, If the Extech says all is OK, is it safe?  How about with a solid green only indication on the GCM device in addition to the Extech?  Is that safe?  Should one's test always use a three-tester test? 
sorry I am not familiar with those...  A NCVT can tell you a bunch, a neon lamp probe even more...
Quote
Granted, neither the Extech nor the GCM devices will actually identify a RPBG condition, apart or together.  if you used the Extech, and all/any of the cords one has made up has an GCM device, there is an automatic second-level test.  Can there be a possibility of a RPBG if there is no indicated reverse polarity, and the ground shows voltage within expected ranges on the Extech?  Would that preclude the actual test with the NCVT?   
?
Quote

I will grant the NCVT is so quick, easy, and positive this question is more a technicality than a practical matter.
If only there was a better way...  8)

JR
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frank kayser

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Re: Right or Wrong? New building has receptacles with Hot and Neutral reversed.
« Reply #23 on: September 20, 2017, 08:05:51 pm »

For me RPBG is a deal breaker-and no way I am gonna have an adapter laying around to fix that-that's a hazard in itself.

Reversed polarity?  Depending on gear and setup.  Obviously, first look for an alternative-however in most modern gear polarity is not an issue-nor really is voltage if something is happy from 90-240 volts.

IMO, polarity is really more of an issue for the electrician's-once they leave leve they have no control over what is plugged in there and if someone plugs in an Eico tube amp like the one I used to run on a metal bookshelf in my room as a teen that has it's chassis tied to one side of the line that can get ugly. If you know and are aware and can control what is plugged in, honestly you are probably OK.  Again, really don't like the idea of an adapter unless it is kept under lock and key for teaching purposes only!





It never ceases to amaze me the translation that occurs between my mind and fingers. (BIG sigh)


The reversal adapter that crossed my mind was a HOT neutral swap, not a GROUND neutral swap as my fingers mistakenly tapped out.



Again, really don't like the idea of an adapter unless it is kept under lock and key for teaching purposes only!


Agreed.  Even if I wrote what I meant, your last statement covers that, too.
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frank kayser

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Re: Right or Wrong? New building has receptacles with Hot and Neutral reversed.
« Reply #24 on: September 20, 2017, 08:22:49 pm »

If these use similar technology to 3 lamp testers, they may have similar vulnerabilities.
JR


D'oh! Never thought of that comparison, but after you pointed out that possibility (probability), I'm just left shaking my head for missing that obvious question.  Damn.


Oh well, they seem to be well made connectors, better than most I've seen and used. The 20a version easily and securely clamps on to 10/3 SEOOW cable.  And Ooooo, the pretty colors, the colors!
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Tim McCulloch

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Re: Right or Wrong? New building has receptacles with Hot and Neutral reversed.
« Reply #25 on: September 20, 2017, 08:31:39 pm »

Here's my take, based on 35 years of not dying or killing anyone with electrical power....

If this *entire* facility is wired in this manner it will likely function in a manner that does not present direct and immediate hazards to the staff or patrons.

The likelihood of fire, injury or death increases significantly if only part of the facility is wired this way and multiple extension cords are run from various places for use in a single location.  It's also a future problem when maintenance, replacement or expansion occurs and this charming little deviation from Code gets "corrected" in the new work, but the old work does not get changed. 
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Stephen Swaffer

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Re: Right or Wrong? New building has receptacles with Hot and Neutral reversed.
« Reply #26 on: September 20, 2017, 10:38:20 pm »

I would agree-unless someone plugs in a vintage amp with a chassis tied to one side of the line.  Chances of that happening?  You might know better than me-my point of view is as an electrician and anything can happen.  I'm only really OK with this if I'm in control.

Even a DVM suffers the same limitations as the 3 light tester-the lack of a known independent ground reference.  That's where an NCVT or neon lamp testers shine.

FWIW, Klein makes several meters with a built in NCVT.  I also see the current Fluke 117 has a NCVT as well as being low impedance to avoid "ghost" voltages.  Looks like a really good tool for quick testing of power-lacking load testing of course.
« Last Edit: September 21, 2017, 07:38:05 am by Stephen Swaffer »
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Scott Holtzman

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Re: Right or Wrong? New building has receptacles with Hot and Neutral reversed.
« Reply #27 on: September 20, 2017, 11:08:21 pm »

I would agree-unless someone plugs in a vintage amp with a chassis tied to one side of the line.  Chances of that happening?  You might know better than me-my point of view is as an electrician and anything can happen.  I'm only really OK with this if I'm in control.

Even a DVM suffers the same limitations as the 3 light tester-the lack of a known independent grouond reference.  That's where an NCVT or neon lamp testers shine.



Here is another fun way reversed neutral ground can get you.  I had a plasma TV that must have had neutral tied to the chassis.  Somehow the outlet on the wall was wired backwards.   I had a genny running the house when the power was off.  The generator was feeding my office upstairs and a small portable air conditioner in the master.  This was during Sandy, the power was off for days, I had everything moved to the garage fridge that was also on the genny. 

So the Sandy part is important as we were bored and I said we can watch a movie off my laptop on the big TV.  I ran an extension cord from the UPS in my office (a 2200w unit) as I didn't want to run the TV right off the generator.  The laptop was plugged directly into the generator.  The fault path was through the laptop and it was sitting on top of one of the speakers and it exploded.  I knew exactly what happened, wife and dog were less than impressed.

Point being is that TV was wired backwards for years and connected to the receiver,  startedwith component video then HDMI and this was never an issue (the stereo rack was not backwards).

Quote
FWIW, Klein makes several meters with a built in NCVT.  I also see the current Fluke 117 has a NCVT as well as being low impedance to avoid "ghost" voltages.  Looks like a really good tool for quick testing of power-lacking load testing of course.

Greenlee makes a screwdriver with one in the handle.  Don't buy it, it's a poor design, you hit the button operating the screwdriver and it beeps incessantly.  If you take it out of the handle it no longer feels right in your hand.

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Tim McCulloch

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Re: Right or Wrong? New building has receptacles with Hot and Neutral reversed.
« Reply #28 on: September 20, 2017, 11:34:10 pm »

I would agree-unless someone plugs in a vintage amp with a chassis tied to one side of the line.  Chances of that happening?  You might know better than me-my point of view is as an electrician and anything can happen.  I'm only really OK with this if I'm in control.

Even a DVM suffers the same limitations as the 3 light tester-the lack of a known independent grouond reference.  That's where an NCVT or neon lamp testers shine.

FWIW, Klein makes several meters with a built in NCVT.  I also see the current Fluke 117 has a NCVT as well as being low impedance to avoid "ghost" voltages.  Looks like a really good tool for quick testing of power-lacking load testing of course.

The guitar amp issue is the same, it only takes the flip of a "polarity" switch on the amp to make it dangerous regardless of how the outlet is wired, but the building wiring issue certainly adds another variable.

One of my concerns is what happens when someone runs an extension cord to a device that has Scott's TV issue or the cord is mis-wired...  The way most local bands and small PA operators must work involves finding multiple circuits from around the venue.  Until something changes in the venue or there is a defective product or AC cable, the dangerous nature of this installation will not be apparent.

The OP asked what should be done, and after thinking this over I believe it needs to be reported to the head of the local AHJ.
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John Roberts {JR}

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Re: Right or Wrong? New building has receptacles with Hot and Neutral reversed.
« Reply #29 on: September 21, 2017, 09:58:55 am »

Here is another fun way reversed neutral ground can get you.  I had a plasma TV that must have had neutral tied to the chassis.
2-wire consumer gear will sometimes wire a capacitor between chassis ground and neutral. The cap should be voltage rated to survive reverse polarity.
Quote
Somehow the outlet on the wall was wired backwards. 
?
Quote
I had a genny running the house when the power was off.  The generator was feeding my office upstairs and a small portable air conditioner in the master.  This was during Sandy, the power was off for days, I had everything moved to the garage fridge that was also on the genny. 

So the Sandy part is important as we were bored and I said we can watch a movie off my laptop on the big TV.  I ran an extension cord from the UPS in my office (a 2200w unit) as I didn't want to run the TV right off the generator.  The laptop was plugged directly into the generator.  The fault path was through the laptop and it was sitting on top of one of the speakers and it exploded.  I knew exactly what happened, wife and dog were less than impressed.
I still don't..
Quote
Point being is that TV was wired backwards for years and connected to the receiver,  startedwith component video then HDMI and this was never an issue (the stereo rack was not backwards).
might be worth more investigation of house wiring.

JR
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Re: Right or Wrong? New building has receptacles with Hot and Neutral reversed.
« Reply #29 on: September 21, 2017, 09:58:55 am »


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