Is the Handbook wrong?

[electrofelon]

I have been going over article 250 as a refresher and I am a bit confused by exhibit 250.34 in the handbook. Here is my thinking on how I would do the grounding and bonding in this situation. I could either run a copper GEC tap to each enclosure, using a bonding bushing on each end of the nipple as per 250.92 A 3, or i could use the nipple as the GEC for that part of the run, in which case i would still need a bonding bushing at each end per 250.92 B. The exhibit shows bonding bushings and bonding jumpers in the panels but not in the wireway. Either I am missing something or the score is me 1, handbook nothing!

 

[infinity]

Re: Is the Handbook wrong?

Since the Neutral is bonded in the wireway and again in the disconnect bonding is only required on one end of the nipple to bond the nipple itself. This could be on either end of the nipple. Exhibit 250.34 is correct.

 

[electrofelon]

Re: Is the Handbook wrong?

Infinity (or anyone else),

Thanks for the explaination, I guess 250.64D was throwing me off:

"Where a service consists of more than a single enclosure.....it shall be permitted to connect taps to the grounding electrode conductor. Each such tap conductor shall extend to the inside of eash such enclosure ...."

I see that the tap method is an option and not required since the neutral is allowed as a dual purpose grounded and grouding conductor on the supply side of the service disconnect. So now i'm trying to think of a situation when the tap method would be prudent? Even if there was no wireway/j-box and each enclosure was fed by its own conduit, could you not bond the GEC to the neutral in one enclosure since the neutrals are bonded where they connect to the service drop or lateral?

 

[al hildenbrand]

Re: Is the Handbook wrong?

The situation that immediately comes to my mind concerns the GEC run once it heads off from the service to the water pipe, rebar, etc.

It is not uncommon for the GEC to be run in a raceway.

When the raceway is nonmetallic and there are conductive pulling access J-boxes along the run, the tap is handy to bond the J-boxes.

 

[pierre]

Re: Is the Handbook wrong?

Felon
Take a look at exhibit 250.32. I believe this is what you are thinking of?

Exhibit .32 and .34 are showing two different types of installation... of which similar requirements are being met, with .34 covering the grounded conductor installation as well as the GEC connection.