2011 NEC Question regarding separating neutrals and grounds on bonded buses

[BMacky]

Had an inspector "remind" me that starting 2011, "even though your neutral and ground buses are bonded in the main panel, the grounds and neutrals should not be on the same bus".

First of all, is he referring to a new Code specific, and what is it?
Second, what would be the rationale behind that if electrically these are the same?

I can see correcting the use of the same lug for a neutral and ground conductor which has been a no-no since I've entered this profession, but think of all the main panel designs that have one large bus for all neutrals and grounds. Does this now mean (if valid) that you need to install a separate ground bus in a new panel and bond it to the neutral?

Is there some other new Code reference that this inspector may be confusing?

Input please. Thanks!


Bob

 

[Dennis Alwon]

IMO, the inspector may be correct depending on how the neutral bar and ground bar are connected. If the ground bar relies on a screw to the enclosure then the neutrals must not be landed. The neutral cannot use the enclosure as continuity to the neutral bar. 200.2(B) NEC 2008 & 2011)

 

[dbuckley]

Second, what would be the rationale behind that if electrically these are the same?

Because ground and neutral are not (and have never been) "the same".

One carries current, and one normally does not. If you mix whites and greens along the same busbar then because of voltage drop along the bar, different green wires will be at slightly different potential to each other.

It used to be that only farmers, telecomms carriers, and audio engineers cared about such things, but now we are in a more wired society it's good to see that Code has finally got with the programme. See this 66 page PDF document from the US Department of Agriculture for more info on grounding practice, and n particular PANI grounding, which is over the top for most installations, but the same basic principles apply.

To the best of my knowledge, no other civilised country permits the use of a single bar for ground and neutral.

 

[iwire]

To the best of my knowledge, no other civilised country permits the use of a single bar for ground and neutral.

Anyplace under the NEC at any service panel.

 

[jbelectric777]

It's only 2011 now, most authorities have not even had a chance to adopt the 2011. Is he talking about feeders remote from the main? or main distribution panels where they are one in the same? (like in most residential homes) How did this inspector get the information? Feeders were never allowed to share grounding with grounded circuit conductors for as long as I could remember.