OT: electical sub panel grounding

[Morgans]

[Morgans]

4, but they are aluminum. Two hots and a neutral, all three insulated, with additional bare conductor.

[Morgans]

"Mike Marlow" wrote

Which is exactly my beef. This guy wants an additional #6 outside the feed.

[Morgans]

wrote

Correctly designed panel with a insulated lug for neutral with a connector screwed onto the frame and into the holes in the lug and tightened down. All I had to do is add a non insulated buss for the all of the grounds and remove the bonding connector.

[Doug Winterburn]

Didja use the black gunk (anti-oxidant paste) on all the aluminum wire panel connections?

[Morgans]

"Doug Winterburn" wrote in

Didja use the black gunk (anti-oxidant paste) on all the aluminum wire panel connections?

You betcha. I payed attnson to all the sparkys I was around! I think mine was green, though.

I was pretty sure this inspector was full of it. I never installed the extra ground, and that was years ago. No problems. I ws just trying to do everything exactly to code, and wanted to check for sure. I think it is safe to say consensus was reached saying the second ground wire is not necessary, and some have said it could be a violation or harmful.

I will go without it and sleep easy.

Jim in NC

[John McCoy]

[e-mail] wrote in news: [e-mail]:

The situation described has them both in the same conduit, if I'm not mistaken. That's not a loop, that's just two parallel conductors (and, if the conduit is EMT, then it's three parallel conductors).

John

[Swingman]

[Lew Hodgett]

---------------------------------------------- Somebody had it right.

Mike Marlow maybe.

A sub panel requires an insulated ground buss as well as an insulated neutral buss.

In addition, a sub panel must be able to disconnect all power under it's control in a maximum of six (6) motions of the hand; otherwise known as the six (6) hand rule.

If more than (6) motions are required to disconnect all branches, then a main c'bkr is required.

SFWIW, a branch c'bkr located in the main panel and feeding the sub panel is also required.

The bonding strap located in the sub panel shall be connected to the insulated ground buss.

The sub panel shall be fed by four (4) conductors (L1, L2, N and G) from the main panel.

The neutral buss and ground buss in the main panel do not have to be insulated but often are.

The bonding strap located in the main panel shall be connected to the ground buss.

The neutral buss and ground buss in the main panel are tied together as well as the earth ground conductor which connects to the earth ground rod driven into the earth at the service point.

The above meets code or did when I was in the business.

Nothing else is required.

Lew

[Morgans]

"John McCoy" wrote

The situation described has them both in the same conduit, if I'm not mistaken. That's not a loop, that's just two parallel conductors (and, if the conduit is EMT, then it's three parallel conductors).

Residential, and not in conduit. This is SE (service entrance cable) and a bare to be copper wire beside the se cable.

[Mike M]

I'm confused by all this, but assuming your feeding your sub panel with three conductors and a ground sized for the OCD then the only reason I can think of for the #6 is that its a separate building and he wants a grounding system which varies from jurisdiction to jurisdiction. #6 being the largest size required to a grounding rod.

MikeM

[krw]

Insulated ground bus (one 's', two and it's a kiss)? Why insulated? It has to be bonded to the case. The neutral has to be isolated from the ground, sure.

The main may be one of the other breaker positions. That is, the sub panel may be back-fed through one of the other breakers, as long as it is clearly marked as the main (disconnect).

Certainly. The wire has to be protected.

Again, why insulated? That makes *no* sense.

If both hots are used, sure. Ground and neutral have to be separated.

*ONLY* if the main is the entrance panel. If it's another sub, they must be separated there, too. In the entrance panel, the grounds need not be separated from the neutrals but it's good practice.

If the main is the entrance.

Lots of other things are required but...

[krw]

Right, but that's *not* what Lew said. Go back and read what you snipped.

The ground bus is *not* isolated in a common panel. The neutral bus

*is* (with a link to bond it in the entrance).

[krw]

Maybe, but that's not needed, either, if it's in conduit.

OTOH, he said,

"A sub panel requires an insulated ground buss as well as an insulated neutral buss."

The "bus" is the multiple-tap connection point, not the wire between the boxes.

We could also all be talking past each other. I wanted to get everyone on the same page, though.

[Morgans]

"Mike M" wrote

I'm confused by all this, but assuming your feeding your sub panel with three conductors and a ground sized for the OCD then the only reason I can think of for the #6 is that its a separate building and he wants a grounding system which varies from jurisdiction to jurisdiction. #6 being the largest size required to a grounding rod.

MikeM

Remember one of the other comments.

This same inspector was later fired for making people do sh*t that was not required by code. He seemed to invent things along the way.

I suspect if I had reported him with my case, that would have been a few days earlier that he got fired.

There is no reason in the world to require an additional ground. I knew that, (or was pretty darn sure) but wanted to confirm it, and I know there were several electricians in the group.

At any rate, I never did the "upgrade" then, and I'm sure not going to do it now!

Jim in NC

[John McCoy]

[e-mail] wrote in news: [e-mail]:

I wonder if the source Lew was quoting meant an "isolated" ground bus (i.e. isolated from the neutral) rather than insulated.

Because I'm with you, insulated ground bus doesn't seem to make sense, when you're going to strap it to the case anyway.

John

[clare]

I would also vote for an "isolated" bus.

[Lew Hodgett]

-------------------------------------------------------------

"John McCoy" wrote:

------------------------------------------------------------------ If you read and understand what was written, you will see that my comments are correct as written.

The NEC does NOT permit multiple paths to ground, but rather only allows a single path between a fault and earth ground.

INSULATED neutral buss and ground buss bars mounted and wired ONLY as described will meet those NEC requirements of having ONLY a single path from fault to ground.

Yes it does make a difference how a system is wired and the equipment used in order to meet the NEC requirements.

Lew

[krw]

Wrong. Ground bars are *not* insulated/isolated from the case. Neutral bars are and strapped when necessary.

Yes, but you're still wrong.

[krw]

Ground "isolated" from the neutral, not from the case. It is screwed right to the case.