bonding before service

[scroot]

OK, I have been asked the question again and confused myself yet again.
First, I always bond neutral and ground at the main service disconnect. Running back out to the utility transformer is the phase conductors, neutral and ground. My utility company says don't run both neutral and ground to their service transformer. Both of these will be connected to the same point (ground) and so one is not needed since it is connected to same point and therefore just an extra wire. The utility bonds neutral to ground at the transformer.
OK, now I'm working on a large site where we are running 13.2KV around the site and serving many buildings from this. So essentially, I am the utility. Should I bond the each buildings transformer neutral to ground and of course also bond the neutral and ground inside the buildings at the main disconnect? Do I need both the neutral and ground between the transformer and main? If I only run the one neutral/ground between the transformer and the main instead of both a neutral and a ground - what do you call this wire - a neutral or a ground?

 

[augie47]

Re: bonding before service

yes
and only 1 wire, a grounded neutral

 

[romeo]

Re: bonding before service

The only time I would see a need for a bonding conductor is in the case of a service lateral with a metal conduit going up a pole. The conduit would need to be provide with a return path to the source in the event of a ground fault. A neutral to case bond is made at the service main and at no where else.

romeo

 

[iwire]

Re: bonding before service

Originally posted by romeo:
The only time I would see a need for a bonding conductor is in the case of a service lateral with a metal conduit going up a pole. The conduit would need to be provide with a return path to the source in the event of a ground fault.

The easiest way to solve that is to simply bond the conduit to the neutral as it exits the conduit.

 

[romeo]

Re: bonding before service

Bob That is another effective method. I have a hard time trying to convince some electricians that it is though.

romeo

 

[augie47]

Re: bonding before service

and a harder time convincing some POCO folks.

 

[eprice]

Re: bonding before service

Originally posted by iwire:
The easiest way to solve that is to simply bond the conduit to the neutral as it exits the conduit.

Yes. In fact, I think it could be argued that running a bonding conductor back from the service disconnect is not an NEC recognized method. 250.92(B) tells us how to bond metal parts on the line side of the disconnect. The only mention of bonding jumpers in that section is to bypass knockouts.