Grounding subpanels, etc.

Having some electrical work re-done by a master electrician in conjunction with putting in a standby generator, and I want to know what to expect since I'm not sure the previous master electrician did it correctly. I know he didn't do a very "clean" job.

The layout has the POCO meter box on the outside wall of my shop. The service entrance rated ATS is directly behind it inside the shop. This Siemens mobile home load center...

http://www.amazon.com/dp/B000UJDSZA?...0&linkCode=asn

...will be mounted beside the ATS and will be fed by the ATS. It has circuits for my shop and my water well pump. The feed-thru lugs in the load center will have cables that go to another load center (same model) mounted beside this one. The second load center contains no breakers except the main breaker. It's only purpose is to be able to shut off power to my house (from outside my house) while maintaining power in my shop. The feed-thru lugs on second one are used for cables that go to my house 200 feet away (underground cable). My house has a "regular" load center with a 200 amp main breaker.

The neutral and ground in my house panel are not bonded. There are four cables running between the load center in my house and the 2nd load center in the shop. I think this part is correct.

The question is...how should the two load panels and the ATS in the shop be set up with regard to neutral/ground bonding and grounding to a ground rod? The last electrician ran a separate ground wire from each of the three panels in the shop to the same outdoor ground rod. The 1st load center (connected to the ATS and containing my shop circuits) has the neutral and ground bonded (using the same bar). The 2nd load center in the shop has the neutral and ground bars separate and not bonded.

So is this how it should be? These load centers are called mobile home load centers. Is that just because of the feed-thru capability?

Thanks,
Ira

 

Your SE ATS is your 1st means of disconnect.
The ATS should be connected to the ground rod, water, etc. at this point.
The neutral and ground should be bonded together at this point only.
The grounds and neutrals should all be separated in any panel downstream from the ATS.
All those connections to the ground rod are not correct at this point.

 

Thanks for the info. If I understand you correctly, only the ATS should have the neutral and ground bonded, and everything "downstream" from the ATS (the two load centers in the shop and one in the house) should have the neutral and ground separate. That means four separate cables from each box to the next. You also said "all those connections to the ground rod are not correct at this point." Do you mean that only the ATS should have a ground wire going to a ground rod?

Thanks,
Ira

 

Correct, your GEC (grounding electrode conductors) must be run back to the ATS and land at the neutral bus.

 

Guys,

Thanks for the help. Hopefully I won't have any problems with the electrician getting it set up correctly this time.

Regards,
Ira

 

Just thought of one more question...

I know I will need to buy ground bars to add to each of the two load centers in my shop, and that the neutral bars will be floating (right?). Should the ground bars float also, or should they be bonded to the box?

Thanks again,
Ira

 

The ground bars should be solidly bonded to the metal enclosures by way of the tapped mounting screws. Only the neutrals float isolated from the box.

 

Well...the electrician set it up wrong. I tried to discuss all of this with him before he started, but he politely told me not to worry, that everything would be done to code. So here's what he did wrong that I can see...

1. All neutrals are bonded to the enclosures (except in the load center in my house, which he didn't touch).
2. The ground from the second load center to the house is connected to the neutral bar at the second load center instead of the ground bar. Although I guess it doesn't make much difference in this case since the neutral bar is incorrectly bonded to the enclosure like the ground bar.
3. The first load center has one ground wire and the second load center has two ground wires, all three going to the same ground rod.
4. The ground wire in the ATS goes to the generator. There is another ground rod beside the generator, and a ground strap from the generator frame to the ground rod. I haven't pulled the generator cover off the check, but I assume the ground wire from the ATS is connected to the generator frame, directly or indirectly. This ground rod is about fifteen feet from the ground rod connected to the two load centers.
5. There is no ground wire between the ATS and first load center.

So, any suggestions on how I convince the "non-electrician" dealer that his master electrician did it wrong? Any websites that show in semi-layman's terms how this should be done?

Thanks,
Ira

 

I forgot to mention...I live in an unincorporated area so there aren't any code inspectors that can come to my rescue on this.

Thanks,
Ira

 

Sorry for bringing up an old thread, but I didn't want to type everything again.

My generator dealer has been silent on this, even though he was supposed to get another opinion several months ago. I guess Hurricane Ike got higher priority.

Can someone please tell me the NEC code that this setup violates, or the one that says how it should be done so I can pass that along to the dealer?

Also, what is the potential danger for the way it is currently set up?

Thanks,
Ira