# detecting outlets with neutral/ground reversed?



## wildleg (Apr 12, 2009)

for 10 bucks or so you can get a plug in tester that will tell you (any hardware). not a bad tool to have. fits in your pocket.


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## bobelectric (Feb 24, 2007)

Stagehands problem. They always make patch panels that aren't to code.


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## B4T (Feb 10, 2009)

The outlet tester also checks for a missing ground.

GREENLEE makes a good one and HD sells them

Welcome to the forum :thumbsup:


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## jeffsw6 (Dec 6, 2009)

I thought those tools could not detect N/G reverse, only hot legs on the wrong conductor.

I have done quite a bit of reading on this subject today and so far the only answer I have come up with involves using an amp meter on the G conductors at the panel end of the circuit(s) and connecting loads to each outlet to discover which loads run current through the ground wire.


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## william1978 (Sep 21, 2008)

I use the 61-051. Check this link.

http://www.idealindustries.com/prod...ectrical_testers/circuit_tester_e-z_check.jsp


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## B4T (Feb 10, 2009)

william1978 said:


> I use the 61-051. Check this link.
> 
> http://www.idealindustries.com/prod...ectrical_testers/circuit_tester_e-z_check.jsp


I used to have that one till the hot prong stayed in an outlet 

I think I will "lose" the GREENLEE one and buy another IDEAL

Mu supply house does not carry the line anymore


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## william1978 (Sep 21, 2008)

That 65-051 is a really nice "monkey face" or whatever the rest of you call'em.


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## Magnettica (Jan 23, 2007)

Seriously?

Not even Kirk Hammet or Slash would attempt to fix the electrical system. Get a real electrician in there to fix it.


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## Speedy Petey (Jan 10, 2007)

I think an Ideal Sure Test is what you are looking for. A bit steep for a plug-in tester but it definitely serves it's purpose.

http://www.idealindustries.com/prodDetail.do?prodId=61-164


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## Magnettica (Jan 23, 2007)

jeffsw6 said:


> I thought those tools could not detect N/G reverse, only hot legs on the wrong conductor.
> 
> I have done quite a bit of reading on this subject today and so far the only answer I have come up with involves using an amp meter on the G conductors at the panel end of the circuit(s) and connecting loads to each outlet to discover which loads run current through the ground wire.


Do you really believe you can learn electrical theory in 24 hours?


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## 480sparky (Sep 20, 2007)

Magnettica said:


> Do you really believe you can learn electrical theory in 24 hours?


It takes some people that long?


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## Magnettica (Jan 23, 2007)

480sparky said:


> It takes some people that long?


Dumbasses maybe 48 hours. 

Amazing how many bars have such faulty wiring. 

OP, seriously, hire a licensed electrician to correct this problem. 

The life you save might be your own. :thumbsup:


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## 480sparky (Sep 20, 2007)

Magnettica said:


> Dumbasses maybe 48 hours......


Geez.. My Wiring 1-2-3 book never even mentioned theory.







So who needs it?


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## william1978 (Sep 21, 2008)

jeffsw6 said:


> I sincerely hope I am not being too big a jerk by posting on your forum while not a licensed electrician.


 We Don't mind just bring some cheese for us rats.:thumbsup:


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## Speedy Petey (Jan 10, 2007)

Jeff, since you are not in the trade this thread would have been closed earlier, but I thought you should get some advice on how to at least diagnose this a bit. You did say you wanted some way of showing the owner what the problem is. I really hope you were not intending to do any work yourself.

If you do run into this again PLEASE inform the owner that there is a problem. Unfortunately this does seem to be a very real issue with places like this.

Once you get the info you need to help explain things I will close this thread.


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## egads (Sep 1, 2009)

I don't think he wants to fix it himself. Just prove to the owner that it is dangerous and an electrician should be brought in. The tester would also allow him to test other venues when setting up.


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## kbsparky (Sep 20, 2007)

I would pack an isolation transformer and plug all my equipment into that to prevent such shock hazards.


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## william1978 (Sep 21, 2008)

egads said:


> I don't think he wants to fix it himself. Just prove to the owner that it is dangerous and an electrician should be brought in. The tester would also allow him to test other venues when setting up.


 I agree.


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## Magnettica (Jan 23, 2007)

What needs to happen is for an electrician to get in there and evaluate the electrical system and access the situation.


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## RePhase277 (Feb 5, 2008)

Run a bonding wire between all the pieces of equipment. That will equalize the potential across the sound system


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## Speedy Petey (Jan 10, 2007)

egads said:


> I don't think he wants to fix it himself. Just prove to the owner that it is dangerous and an electrician should be brought in. The tester would also allow him to test other venues when setting up.


Yup, I agree as well. :thumbsup:


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## william1978 (Sep 21, 2008)

Will the fire alarm shunt all of this music equip. if it went into alarm?


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## bobelectric (Feb 24, 2007)

Use wireless mikes.


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## brian john (Mar 11, 2007)

kbsparky said:


> I would pack an isolation transformer and plug all my equipment into that to prevent such shock hazards.


This would be a quick fix and would be decent for moving from place to place.


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## jeffsw6 (Dec 6, 2009)

Magnettica said:


> Seriously?
> 
> Not even Kirk Hammet or Slash would attempt to fix the electrical system. Get a real electrician in there to fix it.


I never intended to fix anything myself; I just needed to know what kind of tool would identify the fault so the owner will stop ignoring it and get an electrician in to fix it before someone gets injured.

Thanks for the help!

EDIT: I've checked the instructions for the Ideal tester linked here (I believe the other unit operates identically) and it cannot detect N/G reverse. I think my previous post is still correct


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## brian john (Mar 11, 2007)

jeffsw6 said:


> I never intended to fix anything myself; I just needed to know what kind of tool would identify the fault so the owner will stop ignoring it and get an electrician in to fix it before someone gets injured.
> 
> Thanks for the help!


This will allow you to put the owner on notice, whether he fixes it or not, well at least you will have a stand in court should someone get hurt.


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## wildleg (Apr 12, 2009)

I think you are correct. Magnettica hit it on the head - someone needs to open up the panel and check out the ckts in order for you to determine if there is a problem.


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## Ray Cyr (Nov 21, 2007)

jeffsw6 said:


> I never intended to fix anything myself; I just needed to know what kind of tool would identify the fault so the owner will stop ignoring it and get an electrician in to fix it before someone gets injured.
> 
> Thanks for the help!
> 
> EDIT: I've checked the instructions for the Ideal tester linked here (I believe the other unit operates identically) and it cannot detect N/G reverse. I think my previous post is still correct


Is this a house system or is each provider bringing their own gear?


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## jeffsw6 (Dec 6, 2009)

Ray Cyr said:


> Is this a house system or is each provider bringing their own gear?


Each provider brings their own audio system. Lights are sometimes supplied by bands, sometimes by the audio provider, and in my case on Friday, the band had 8 cans on dimmers, and I supplied two DMX fixtures. I run my amplifiers on stage power and my mixing console and outboard on a different circuit about 40 feet back from the stage where the house snake fan-tail is located.

There is no disconnect at this venue for portable distribution equipment. There are 8 5-15R duplex receptacles scattered around the stage on 3 or 4 circuits. Which outlets are on which circuits is unknown.

The wiring in this place is scary. Not the worst venue I've been in by any means, but I work there a lot. They had a serious panel fire approx. December 29th '08 and were closed for 3 or 4 days (and lost thousands of dollars by not being open New Year's Eve.) The local inspectors made them install an extra exit sign and a safety opening mechanism on an exit that was previously locked all the time. That's it. They have Wal-Mart power strips attached to walls and equipment that is basically permanent running off them (cash registers, TVs, drink coolers, smoke eaters, etc.) and if the inspectors didn't do anything about that mess, I know they would take no interest in a relatively minor problem like this. It will not get fixed unless I find out how to show what and where the problem is.


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## readydave8 (Sep 20, 2009)

jeffsw6 said:


> I never intended to fix anything myself; I just needed to know what kind of tool would identify the fault so the owner will stop ignoring it and get an electrician in to fix it before someone gets injured.
> 
> Thanks for the help!
> 
> EDIT: I've checked the instructions for the Ideal tester linked here (I believe the other unit operates identically) and it cannot detect N/G reverse. I think my previous post is still correct


I'm not too clear on why you assume that the n/g's are reversed. If you mean at the receptacle, the white's hooked to the green screw? Seems like an unlikely mistake.

We see n/g connections, sometimes there is no grounding conductor (bare or green) and the installer will jump from the neutral to the ground screw (saw this again this week). Or a neutral is touching a ground.

Probably the reason the tester does not check for reversed n/g is because its not likely to happen. A improper n/g connection can be checked, if its unsusally low ohm may be present.


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## jeffsw6 (Dec 6, 2009)

readydave8 said:


> I'm not too clear on why you assume that the n/g's are reversed. If you mean at the receptacle, the white's hooked to the green screw? Seems like an unlikely mistake.


The problem has only been noticed with phase-control dimmers in use. I do not thoroughly understand how they work but if this would cause the neutral to have some potential with reference to ground, and some outlets have N/G reversed, it would explain my symptom.



> We see n/g connections, sometimes there is no grounding conductor (bare or green) and the installer will jump from the neutral to the ground screw (saw this again this week). Or a neutral is touching a ground.


This could also explain it if the dimmers are making the instruments slightly hot with reference to the PA ground because of a N/G bond in the receptacles?



> Probably the reason the tester does not check for reversed n/g is because its not likely to happen. A improper n/g connection can be checked, if its unsusally low ohm may be present.


The testers can't check for that condition because they have no way to differentiate between N and G.


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## wildleg (Apr 12, 2009)

some dimmers, unfortunately, use the ground for some small leakage current. modern dimmers I have used leak current in the order of < 1ma.


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## Magnettica (Jan 23, 2007)

jeffsw6 said:


> Each provider brings their own audio system. Lights are sometimes supplied by bands, sometimes by the audio provider, and in my case on Friday, the band had 8 cans on dimmers, and I supplied two DMX fixtures. I run my amplifiers on stage power and my mixing console and outboard on a different circuit about 40 feet back from the stage where the house snake fan-tail is located.
> 
> There is no disconnect at this venue for portable distribution equipment. There are 8 5-15R duplex receptacles scattered around the stage on 3 or 4 circuits. Which outlets are on which circuits is unknown.
> 
> The wiring in this place is scary. Not the worst venue I've been in by any means, but I work there a lot. They had a serious panel fire approx. December 29th '08 and were closed for 3 or 4 days (and lost thousands of dollars by not being open New Year's Eve.) The local inspectors made them install an extra exit sign and a safety opening mechanism on an exit that was previously locked all the time. That's it. They have Wal-Mart power strips attached to walls and equipment that is basically permanent running off them (cash registers, TVs, drink coolers, smoke eaters, etc.) and if the inspectors didn't do anything about that mess, I know they would take no interest in a relatively minor problem like this. It will not get fixed unless I find out how to show what and where the problem is.



Jeff, that place sounds like a tinderbox if you ask me. You have no business poking around playing electrician. What if you do something while you're "looking for the problem" you make it worse and the place burns down? How would you plead in court? You're better off calling the building department in that town and filing a complaint, or concern, whatever. The last thing you want to do is start opening outlets up looking for the problem.


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## jeffsw6 (Dec 6, 2009)

Agreed, I have no intention of opening any boxes. If I can figure out a way to test with simple tools like a VOM though, that would help me.


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## RePhase277 (Feb 5, 2008)

There is no way to test whether a neutral and ground are reversed without applying a load and seeing which wire carries it. The tester mentioned cannot tell the difference because they are tied together anyway.

Get a long piece of #12 and jump all the equipment together. This will bring them all to one potential and may eliminate the problem.


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## Mr. Sparkle (Jan 27, 2009)

Sounds like this place was wired by the same person that does the wiring in most bars and nightclubs, those owners are notorious for using handymen, usually employees or members of a local band who frequents the club....


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## waco (Dec 10, 2007)

A Sperry three light plug-in tester will show open ground, open neutral, hot/ground reverse and hot/neutral reverse, but I think the problem you are seeing is more about the ways music equipment is built than the building wiring or, at least, some of both. As suggested, direct bonding of the equipment would probably help.


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## Vintage Sounds (Oct 23, 2009)

Bonding all the stuff together would help but in a musical/bar environment where things are only set up temporarily and moved around a lot, it's probably not really a practical solution unfortunately. Someone is going to trip over it, or accidentally/deliberately pull it out, or protest against some foreign wire being brought near their almost-mint 1966 Vox AC30 amp.

Another problem is that some old instrument amps that originally only had a 2-prong cord also had a "polarity" switch to reverse the hot and neutral. You can imagine where this leads. A competent amplifier tech always disables this switch and installs a grounded power cord when an amp comes in for service or maintenance but there are plenty of these things out there which haven't been fixed either because they haven't been taken in or the owner wants it to stay "all original" 

If you bond all the gear together and one of the amps has a polarity switch, which happens to be set so that the chassis is live...that creates a short to ground through one of the other pieces of bonded gear which IS grounded. The breaker will trip unless your bar is rocking Federal Pacific breakers in which case...run


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## sparky105 (Sep 29, 2009)

jeffsw6 said:


> Agreed, I have no intention of opening any boxes. If I can figure out a way to test with simple tools like a VOM though, that would help me.


hook up the last system that the band got a poke and spray down the stage. hand the owner the instrument or the mike. he'll get it fixed after that:whistling2:


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## readydave8 (Sep 20, 2009)

jeffsw6 said:


> The problem has only been noticed with phase-control dimmers in use. I do not thoroughly understand how they work but if this would cause the neutral to have some potential with reference to ground, and some outlets have N/G reversed, it would explain my symptom.
> 
> 
> This could also explain it if the dimmers are making the instruments slightly hot with reference to the PA ground because of a N/G bond in the receptacles?
> ...


zero ohms between neutral and ground would indicate an improper connection


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