When to bond neutral with ground

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Peter323

Member
Can somebody point me to an explanation of when to bond the neutral with the ground in the panel board.
Thanks for your help.
 

Peter323

Member
Thank You. I was trying to prove a point to a "fellow electrician". I saw him installing a sub-panel where he bonded the neutral with equipment ground and on top of that added a bond to the building steel frame.
 

tryinghard

Senior Member
Location
California
Peter323 said:
Can somebody point me to an explanation of when to bond the neutral with the ground in the panel board.
Thanks for your help.

It's easier to understand starting from when you can't, check out:
250-24(A)(5)
250-142(B)
250-32(B)(1)

Compared to when you can:
250-30(A)(1)
250-32(B)(2)
 

Peter323

Member
iwire said:
Was that panel supplied directly from a transformer?



No it was not. It was wired to a meter bank about 80' away. It is a condo building where each floor has a common utility room with meters and disconnects.
 

Peter323

Member
tryinghard said:
It's easier to understand starting from when you can't, check out:
250-24(A)(5)
250-142(B)
250-32(B)(1)

Compared to when you can:
250-30(A)(1)
250-32(B)(2)


Thanks. I'll take a look at that today
 

hillbilly

Senior Member
Peter323 said:
No it was not. It was wired to a meter bank about 80' away. It is a condo building where each floor has a common utility room with meters and disconnects.

Is there a main disconnect ahead of these "sub panels"?
 

hillbilly

Senior Member
Peter323 said:
Yes, there is. At the meter.

Let me get this straight.

You have a multi-floor condo building.
Each floor has one utility room that contains a meter bank supplying a seperate meter and disconnect for each condo on that floor.
From each disconnect, there is a dedicated 4 wire feeder to a breaker panel in each condo.
Each breaker panels supplies only the circuits in that condo.

Your "electrician friend" has bonded the grounded (neutral) and equipment grounds in each sub-panel, and also bonded the building steel from each sub-panel....correct?

steve
 

tryinghard

Senior Member
Location
California
In your situation you cannot bond the neutral unless you meet all the criteria of 250-32(B)(2), and I understand you are not involved with a transformer therefore 250-30(A)(1) does not apply.

I also understand your situation is one building and 250-32 is for two or more buildings; see 250-142-(B) and 250-24(A)(5)
"A grounding connection shall not be made to any grouded circuit conductor [neutral] on the load side of the service disconnecing means"
&​
"Except as permitted in 250-30(A)(1) and 250-30(B), a grounded circuit conductor shall not be used for grounding non-current-carrying metal parts of equipment on the load side of the service diconneting means"
1113854601_4.jpg
&​
1113923626_6.jpg
Do not bond the neutral, if done erroneously it will dangerously cause current to flow where it does not belong
 
Last edited:

Peter323

Member
hillbilly said:
Let me get this straight.

You have a multi-floor condo building.
Each floor has one utility room that contains a meter bank supplying a seperate meter and disconnect for each condo on that floor.
From each disconnect, there is a dedicated 4 wire feeder to a breaker panel in each condo.
Each breaker panels supplies only the circuits in that condo.

Your "electrician friend" has bonded the grounded (neutral) and equipment grounds in each sub-panel, and also bonded the building steel from each sub-panel....correct?

steve


Basically yes, the only difference is that there only a 3-wire feeder because the conduit is used as the ground electrode.
 

Peter323

Member
tryinghard said:
In your situation you cannot bond the neutral unless you meet all the criteria of 250-32(B)(2), and I understand you are not involved with a transformer therefore 250-30(A)(1) does not apply.

I also understand your situation is one building and 250-32 is for two or more buildings; see 250-142-(B) and 250-24(A)(5)
"A grounding connection shall not be made to any grouded circuit conductor [neutral] on the load side of the service disconnecing means"
&​
"Except as permitted in 250-30(A)(1) and 250-30(B), a grounded circuit conductor shall not be used for grounding non-current-carrying metal parts of equipment on the load side of the service diconneting means"
1113854601_4.jpg
&​
1113923626_6.jpg
Do not bond the neutral, if done erroneously it will dangerously cause current to flow where it does not belong


Section 250.24 (A) (5) shows exactly what he did. It shows the exact violation.
Well, now I have proof that I was right.
Thanks a bunch for your help.
 
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