Grounding coductor termination at panel

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rpmall

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What does the Code say about terminating a grounding conductor at the neutral bar of a panel? At first thought one would have to say absolutely not but in another way, one could justify it maybe by saying that electrically, it does not make much difference. What should the prevailing wisdom be here?
 
250.24(A)(5). The neutral and ground points are electrically identical at the main service, or at the first panel after a separately derived system, but not further downstream.

Welcome to the forum.
 
rpmall said:
What does the Code say about terminating a grounding conductor at the neutral bar of a panel? At first thought one would have to say absolutely not but in another way, one could justify it maybe by saying that electrically, it does not make much difference. What should the prevailing wisdom be here?
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After the first means of disconnect, never the twain shall meet.:)
 
rpmall said:
What does the Code say about terminating a grounding conductor at the neutral bar of a panel?
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It depends on the context. A feeder EGC or a BC EGC? Which panel? What's wrong with the grounding in this panel?
 
charlie b said:
250.24(A)(5). The neutral and ground points are electrically identical at the main service, or at the first panel after a separately derived system, but not further downstream.

Welcome to the forum.
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I wouldn't want to see a bunch of neutrals landed on a ground bar attached to the enclosure with just a few 10/32 screws.
 
busman said:
I wouldn't want to see a bunch of neutrals landed on a ground bar attached to the enclosure with just a few 10/32 screws.
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I don't like to see the 10-32 screws a lot of load centers have to connect the MBJ to the can where there is 22k AIC fault current available.. but.. apparently UL is satisfied just as they are with the field installed ground bars as Dennis mentions. Apparently, no problem.
 
rpmall said:
What does the Code say about terminating a grounding conductor at the neutral bar of a panel? At first thought one would have to say absolutely not but in another way, one could justify it maybe by saying that electrically, it does not make much difference. What should the prevailing wisdom be here?
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At the service or source of a SDS (generally), neutrals and EGC can be landed at the same terminal bar.
But on a feeder or separate building, neutrals and grounds are always kept separate (under the 2008 NEC)
The code does not explain why its not allowed, if you do this it will cause objectionable current...shocks, fires, improper operation of electronics
 
infinity said:
That would violate 200.2(B).
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That was the point of my post (although I should have been more explicit about the code violation). Although I'm sure he didn't mean it that way, Charlie's post made it sound like the installer could just pick a bar (ground or neutral) and land either one there. I know we've all seen this violation in the field.

Mark
 
busman said:
Charlie's post made it sound like the installer could just pick a bar (ground or neutral) and land either one there. I know we've all seen this violation in the field.
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I hope that was not anyone's interpretation. I said nothing about landing wires.

We bond the N and G bars together at the main panel, and again when we create a separately derived system. At these locations, the N and the G are electrically identical. Downstream of these locations, the N and G need to be kept separate. If they are connected to each other at a downstream point, it is not the same thing as being connected at the main panel. They are not electrically identical, because it would create a parallel path for neutral current to return to the source via the EGC. That is the "objectionable current" that Tom mentioned.
 
charlie b said:
I hope that was not anyone's interpretation. I said nothing about landing wires.

We bond the N and G bars together at the main panel, and again when we create a separately derived system. At these locations, the N and the G are electrically identical. Downstream of these locations, the N and G need to be kept separate. If they are connected to each other at a downstream point, it is not the same thing as being connected at the main panel. They are not electrically identical, because it would create a parallel path for neutral current to return to the source via the EGC. That is the "objectionable current" that Tom mentioned.
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Charlie - I hope I didn't offend you. I know you know the difference, but in my opinion, the quote - "the N and the G are electrically identical" could be taken to mean that they are functionally the same and that a neutral can be landed on a ground bar. I've seen it done many times, so plenty make this mistake.]

Mark
 
Grounding termination at panel

Grounding termination at panel

Thanks again guys. Definitely appreciate everyone's input.
 
busman said:
That was the point of my post (although I should have been more explicit about the code violation). Although I'm sure he didn't mean it that way, Charlie's post made it sound like the installer could just pick a bar (ground or neutral) and land either one there. I know we've all seen this violation in the field.

Mark
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Busman and Charlie may be referencing two different things. Sounds like Busman is referencing an EGC ground bar that is only attached to the enclosure via mounting screws. The enclosure is bonded to the neutral via a bonding jumper. In that scenario you could not land a netral on that EGC bar due to 200.2(B). If there are two bars in a panel that are linked together by the manufacturer, such as in a residential panel, then you can land both the neutrals and EGC's on either of those bars.
 
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