"Double Ground" or "Parallel Bond"

[Beniah Naylor]

When I write up a correction to bond metal service nipples between the meter and the first means of disconnect in accordance with 250.92(B) (typically accomplished with a bonding bushing), I sometimes receive pushback from the electricians who say that they are concerned about creating a parallel bond or a double ground, or various slang terms that I am unfamiliar with. They say that the utility provider and other inspectors have dinged them for installing a bonding bushing on that nipple, when the nipple is already connected to the meter can and main disconnect cabinet with standard locknuts, thereby bonding the nipple twice. Some electricians also say that you can't put a bonding bushing on both sides of the nipple for the same reason (which is not required and I'm not sure why you would...).

What are they talking about? What hazard would be associated with a "parallel bond", what code sections would apply, or is this an industry myth?

Thanks!

 

[ICE]

I'm going with it's a myth.

"Standard locknuts or bushings shall not be the only means for the bonding required by this section but shall be permitted to be installed to make a mechanical connection of the raceway(s)."

Shirley it is recognized that multiple means for bonding can and do exist. Adding the word "parallel" is supposed to create a suspicion of opps that's wrong. It comes from the obvious wrong of not isolating a neutral from ground at a device which creates a parallel path for neutral current.