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Author Topic: Grounding to the neutral bar?  (Read 20629 times)

Jeff Bankston

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Re: Grounding to the neutral bar?
« Reply #20 on: September 19, 2013, 08:44:24 pm »

i am a commercial journeyman electrician. yes you connect the ground to the neutral bus "IF" theres no other ground buss. the neutral is always connected at the service via the "neutral bonding jumper" aka "neutral disconnect" jumper which is either a lenght of wire or a short piece of buss bar.
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Jonathan Johnson

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Re: Grounding to the neutral bar?
« Reply #21 on: September 20, 2013, 01:23:31 am »

I once measured the "ground" voltage between two sides of a large warehouse (1,000,000 square feet or so) and found there was a 5 volt difference, even with all those I-beams interconnecting everything. The currents involved must have been HUGE, but was never noticed plugging in single piece of gear.

Consider all the environmental sources of electromagnetic radiation. Just the sun beating down on a metal building represents an enormous amount of energy. Then you have the magnetism of the earth itself. (From this perspective, man-made EMF is miniscule.) This EMF energy can be demodulated by the steel in the building, resulting in the voltages you see. And yes, considering how low the resistance between two points in that warehouse must be, that does represent a huge amount of current, possibly hundreds of amps.

But if you look at the cross-sectional area of conductor involved (that is, the steel of the building), it's also huge. But if you take a fraction of that area -- say, the area of an 18 AWG wire -- the current flowing through that fractional area is also fractional and may only be a few milliamps or less.

That doesn't mean you won't have problems (as Mike found out).
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Jim McKeveny

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Re: Grounding to the neutral bar?
« Reply #22 on: October 21, 2013, 09:07:46 am »

There are some judgments to be made here:

Is the box itself metallic and connected via grounded conduit? Ground to the conduit. The box-to-conduit connection may not be reliable.

If the panel cover is missing, the other breakers are different brands and ages, and the neutral bar looks loose, and half the neutral bar locations are stripped, and the main lugs look like a screwdriver was used instead of the proper Allen Key...RUN AWAY!



« Last Edit: October 21, 2013, 06:49:26 pm by Jim McKeveny »
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Jeff Bankston

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Re: Grounding to the neutral bar?
« Reply #23 on: October 21, 2013, 04:16:15 pm »

There are some judgments to be made here:

Is the box itself metallic and connected via grounded conduit? Ground to the conduit. The box-to-conduit connection may not be reliable.

If the panel cover is missing, there other breakers are different brands and ages, and the neutral bar looks loose, and half the neutral bar locations are stripped or, and the main lugs look like a screwdriver was used instead of the proper Allen Key...RUN AWAY!
+ ! run away run away !
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Jonathan Johnson

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Re: Grounding to the neutral bar?
« Reply #24 on: October 21, 2013, 05:00:12 pm »

Is the box itself metallic and connected via grounded conduit? Ground to the conduit. The box-to-conduit connection may not be reliable.
What about the box-to-conduit at the next box up the line... or the one at the service panel? There are many potential points of failure. I've had to tighten conduit locknuts to get a good ground.
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duane massey

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Re: Grounding to the neutral bar?
« Reply #25 on: October 22, 2013, 12:52:31 am »

I have come across many, many non-compliant electrical systems down here in Texas. Heck, you get out into the rural areas where there IS no electrical inspector or code and you can find all sorts of interesting (and dangerous) things. It is quite common to find romex run throughout a building with no grounds connected at the outlets, or #14-2 romex tied to a 30a breaker. Back in "the day" when our band played these halls out in the sticks we carried a box with every brand of breaker just to be able to perform, which was still better than some of the other acts who used big alligator clips to go straight to the rails.
I'm very, very glad those days are long gone.
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Duane Massey
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Tommy Peel

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Re: Grounding to the neutral bar?
« Reply #26 on: October 22, 2013, 01:21:27 am »

I have come across many, many non-compliant electrical systems down here in Texas. Heck, you get out into the rural areas where there IS no electrical inspector or code and you can find all sorts of interesting (and dangerous) things.

+1  Rural areas can get really interesting really fast...

Sent from my Nexus 4 using Tapatalk

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Tom Bourke

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Re: Grounding to the neutral bar?
« Reply #27 on: October 22, 2013, 03:02:12 am »

+1  Rural areas can get really interesting really fast...

Sent from my Nexus 4 using Tapatalk
I think that is part of the divide on this discussion.  It is easy to just get a licensed electrician when your in a decent sized metropolitan area.  When your an hour from the nearest thing resembling a town there are no electricians.  The rules start to become more of a political/popularity contest.  One of the most dangerous situations I ever saw was a county maintenance guy who threw his weight around and got bonus pay to do a "tie in." When I arrived I found an open door to a room with some soow 6-3 laying on the ground.  One end was running in the panel to a 50A breaker that was ON.  The other end was open ends, laying on a wet cement floor inches from a copper water pipe feeding 2 public bathrooms.  WTF!!!

I have also run into my share of licensed electricians who did not know shit about electricity, history of power distribution, and other knowledge needed to make safe and clean power available.  I was talking to one of the supervising electricians for a theatre upgrade I was involved with about older 3 phase systems.  He said most of the young electricians under him knew nothing about the old or odd 3 phase systems.

I think it is important that we, as production professionals, at least learn to recognize the various power configurations and potential safety failure points.  We may not be certified or hold the licence to "fix" the problems.  However it is our responsibility to recognize and be able to articulate to others what problems we find.

Terms like qualified, competent, certified, and licensed have very specific meanings when dealing with NEC, OSHA, insurance, and other legal situations. https://www.osha.gov/pls/oshaweb/owadisp.show_document?p_table=STANDARDS&p_id=10618

We should, at a minimum, strive to meet the definitions of qualified and competent.  This means getting training and experience.  We also have to understand our local laws.  Where I use to live I could do any electrical work I wanted to my house, including the main feeder and meter base, as long as I had a permit and it was inspected.  In the next town over I could not even replace an outlet.  Where I live now I am not allowed to install low voltage signal lines with out a licence.  However, I can legally do a tie in to a 120/208 400A disconnect with out a licence, if the venue allows.
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Jamin Lynch

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Re: Grounding to the neutral bar?
« Reply #28 on: October 25, 2013, 11:19:05 am »

I think that is part of the divide on this discussion.  It is easy to just get a licensed electrician when your in a decent sized metropolitan area.  When your an hour from the nearest thing resembling a town there are no electricians.  The rules start to become more of a political/popularity contest.  One of the most dangerous situations I ever saw was a county maintenance guy who threw his weight around and got bonus pay to do a "tie in." When I arrived I found an open door to a room with some soow 6-3 laying on the ground.  One end was running in the panel to a 50A breaker that was ON.  The other end was open ends, laying on a wet cement floor inches from a copper water pipe feeding 2 public bathrooms.  WTF!!!

I have also run into my share of licensed electricians who did not know shit about electricity, history of power distribution, and other knowledge needed to make safe and clean power available.  I was talking to one of the supervising electricians for a theatre upgrade I was involved with about older 3 phase systems.  He said most of the young electricians under him knew nothing about the old or odd 3 phase systems.

I think it is important that we, as production professionals, at least learn to recognize the various power configurations and potential safety failure points.  We may not be certified or hold the licence to "fix" the problems.  However it is our responsibility to recognize and be able to articulate to others what problems we find.

Terms like qualified, competent, certified, and licensed have very specific meanings when dealing with NEC, OSHA, insurance, and other legal situations. https://www.osha.gov/pls/oshaweb/owadisp.show_document?p_table=STANDARDS&p_id=10618

We should, at a minimum, strive to meet the definitions of qualified and competent.  This means getting training and experience.  We also have to understand our local laws.  Where I use to live I could do any electrical work I wanted to my house, including the main feeder and meter base, as long as I had a permit and it was inspected.  In the next town over I could not even replace an outlet.  Where I live now I am not allowed to install low voltage signal lines with out a licence.  However, I can legally do a tie in to a 120/208 400A disconnect with out a licence, if the venue allows.

You hit the nail on the head!

Down here in South Texas we have a lot of "out in the middle of nowhere" gigs. Getting an electrician out to fix a problem a couple of hours before show time just isn't going to happen. And walking away isn't the other option.  So we have to do what we can.

Just a week ago I was hired to do provide sound and lights for a small gig. I took everyone's advice and drove to the location...twice...to discuss power requirements and check out the venue. I specifically went over exactly what was required. The promoter said,"I'll have an electrician out here to hook up the proper power." When I showed up there was a generator, OK no problem I'll just use that. Well there was no cable or spider box and only 2 circuits on the generator. So what should I have done in this case? Oh, PS,  It's a one hour round trip drive.

Just because you go out to the location and specify exactly what you need doesn't mean you' re going to get it. So if I walk away, that's 2 in one month that I'm told I should walk away from. Can't afford to do that.
« Last Edit: October 25, 2013, 11:34:30 am by Jamin Lynch »
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Tim McCulloch

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Re: Grounding to the neutral bar?
« Reply #29 on: October 25, 2013, 11:36:09 am »

You hit the nail on the head!

Down here in South Texas we have a lot of "out in the middle of nowhere" gigs. Getting an electrician out to fix a problem a couple of hours before show time just isn't going to happen. And walking away isn't the other option.  So we have to do what we can.

Just a week ago I was hired to do provide sound and lights for a small gig. I took everyone's advice and drove to the location...twice...to discuss power requirements and check out the venue. I specifically went over exactly what was required. The promoter said,"I'll have an electrician out here to hook up the proper power." When I showed up there was a generator, OK no problem I'll just use that. Well there was no cable or spider box and only 2 circuits on the generator. So what should I have done in this case?

Just because you go out to the location and specify exactly what you need doesn't mean you' re going to get it. So if I walk away, that's 2 in one month that I'm told I should walk away from. Can't afford to do that.

You go to the artist and say "The promoter wants me to use inadequate and potentially unsafe electrical service.  As the promoter is my client I will do whatever he wants me to do in whatever manner is possible.  I'm telling you this as a courtesy and to give you an opportunity to get the promoter do this in a safe manner."

If anything bad happens, you're already on the hook for knowing better but not insisting on a dangerous situation being corrected, so you might as well tell the band you don't mind subjecting them to electrocution because the promoter is a cheap-skate asshole that doesn't give a damn about the safety of the band, your crew/system, and potentially the safety of the public as well.  These fuckers should be taken out and shot.
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