EGC's in Subpanel onto EGC Terminal Bar

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joe tedesco

joe tedesco

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Boston, Massachusetts
http://joetedesco.com/nec/photos/a4.jpg
A "terminal bar" used for the termination of equipment grounding conductors is shown here on the right side of this cabinet.

This cabinet encloses a panelboard, and is usually called a "subpanel," and the panelboard's grounded conductor (neutral concuctor, with the white identification) is "isolated" or "floating from the metal cabinet, or so called "can" and the EGC terminal is "BONDED" to the can.

This is a "terminal bar" and this is where the EGC's are to be secured under each terminal, some of which may only allow two of the same size per terminal.

The panelboard cover will include this information.

QUESTION: Are EGC's allowed to be spliced and "pigtailed" as shown below?

Here's a good example of what not to do in any panelboard, or approve when it comes to the equipment grounding conductors that are terminated in any type of cabinet:

http://joetedesco.com/nec/photos/twist1.jpg

The rule in 384-20, or now 408.20 was added to the code a long time ago to put a stop to this method.

In addition, the NEC 1989 TCR, on Page 352 for Proposal 9-142, Section 384-27, Log #1039 was "Accepted in Principle" and included in the substantiation were the following words:

"The second sentence is changed to eliminate superfluous wording"

The committee also changed the Section number from 384-27 to 384-20.

NECH 408.20 Commentary:
Courtesy: www.nfpa.org
A separate equipment grounding conductor terminal bar must be installed and bonded to the panelboard for the termination of feeder and branch-circuit equipment grounding conductors.

Where installed within service equipment, this terminal is bonded to the neutral terminal bar. Any other connection between the equipment grounding terminal bar and the neutral bar, other than allowed in 250.32, is not permitted.

If this downstream connection occurs, current flow in the neutral or grounded conductor would take parallel paths through the equipment grounding conductors (the raceway, the building structure, or earth, for example) back to the service equipment.

Normal load currents flowing on the equipment grounding conductors could create a shock hazard. Exposed metal parts of equipment could have a potential difference of several volts created by the load current on the grounding conductors.

Another safety hazard created by this effect, where subpanels are used, is arcing or loose connections at connectors and raceway fittings, for example, creating a potential fire hazard.
Click to expand...
Photos: www.joetedesco.com

[ July 29, 2003, 05:09 AM: Message edited by: joe tedesco ]
 
Re: EGC's in Subpanel onto EGC Terminal Bar

Joe
When driving home from work most people will take the same route all the time because of habit, they are veeerrry comfortable with it. Make them take another route and they get uncomfortable and generally irritated.
The same happens in the installation process (training) in our industry. Whatever way you were taught how to install something, you become very comfortable doing it that way.
From the way I see it, the only way to reduce this type and other incorrect installations is to properly teach the new installers the correct way from the beginning of their training.
That is a large issue of which I am not sure how it will be soon be remedied.
I personally believe part of the training should be ATTITUDE. The proper attitude will go a long way towards the other parts of the training necessary.

Pierre
 
Re: EGC's in Subpanel onto EGC Terminal Bar

Where is the violation? Edit: OK I see the copper strip now.

[ July 20, 2003, 08:48 AM: Message edited by: bennie ]
 
Re: EGC's in Subpanel onto EGC Terminal Bar

I count eleven 1/2 size breakers with thirteen circuits.

The code section described, first appeared in 1968. 384-27.

The installation shown, is not pretty, but was legal before 1968.

[ July 20, 2003, 11:44 AM: Message edited by: bennie ]
 
Re: EGC's in Subpanel onto EGC Terminal Bar

I believe Joe is showing the two pictures to point out the difference of the proper method and the improper method of installing a ground bar in subpanels.

Pierre
 
Re: EGC's in Subpanel onto EGC Terminal Bar

Pierre, let's flash back to the 84 code book just for conversation. (this appears to be an older installation)

Now lets install a lug large enough to accomodate a conductor sized accordingly (for 250-95) and then join all the EGC's using a connection that would satisfy 250-113 or 250-114, (the split bolts if listed for the number and combination of conductors could suffice) we would be legal.

Roger
 
Re: EGC's in Subpanel onto EGC Terminal Bar

Is this a subpanel with a shunt trip main breaker?

I just noticed I'm past 1600. :roll:

[ July 20, 2003, 12:02 PM: Message edited by: bennie ]
 
Re: EGC's in Subpanel onto EGC Terminal Bar

Hello Roger
Is that 'flash like in ARC FLASH :D ?
I do not have the '84 code here, but at my office. I have read enough of your past posts to be able to say that I trust you to be correct.

I notice that some of the smaller 'fittings' have plastic bushings on them. Do you think this is required? Roger in a friendly manner I am testing you, if you don't mind. This issue seems to cross up a lot of guys.

Pierre

[ July 20, 2003, 12:53 PM: Message edited by: pierre ]
 
Re: EGC's in Subpanel onto EGC Terminal Bar

Hello Pierre, I guess "flash" is probably not the right word to use in our industry. :)

Now to your question,
Roger in a friendly manner I am testing you, if you don't mind.
Click to expand...
I don't mind at all.

I think testing each other here happens all the time and shouldn't be offensive to anyone. There are times things do get heated though and can still be informative and educational.

Of course people can hurt others if not handled (worded) in the right way. I hope the members here police me if I get out of hand.

The bushings would not be necessary for the conductors smaller than #4 unless we are looking at type AC.

I'm being lazy and not looking in the 84 code, just responding from memory in relation to recent codes. I just got in from the lake and didn't have quite the luck you did, but I did have fun catching Blue Gill on light tackle.

Roger

[ July 20, 2003, 06:20 PM: Message edited by: roger ]
 
Re: EGC's in Subpanel onto EGC Terminal Bar

Sorry, I don't understand the panel. There appears to be two different ones.
 
Re: EGC's in Subpanel onto EGC Terminal Bar

Thanks Roger: I thought I was losing it. :D What is the point of these pictures? There is likely nothing wrong with the grounding method. The other panel looks like a remodel due to the unused breakers.

Prior to 1968 there was no reference to methods of connection for equipment ground conductors. There was not many equipment ground conductors at that time. The photograph is unusual, due to the quantity of wires. The copper ground strap may be unconventional, but in lieu of specific instructions, there is nothing wrong with this if done before adopting the 1968 code.

[ July 20, 2003, 11:43 PM: Message edited by: bennie ]
 
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