Electrical question:
We are doing our own electrical circuit for the whole house. We need the answer very soon, we hope we could go with the inspection this week. Please help. This is the problem:

We have temporary service through a GFI outlet at the street. The service is grounded to the re-bar in the slab foundation (like a grounding rod).
We have finished the household circuit connections. We have tested each circuit by a male to male plug from the street temporary outlet to an outlet on each circuit, and turning on switches etc. All is in order.
The Service Entrance consists of a 200A meter box outside, and a breaker box inside. The foundation #6 ground lead (same as to temp service) runs through the wall and through the inside box, out through the 3 inch conduit connector to the outside meter box. It is attached to 3 inch conduit, and to the neutral “grounding” bar. This instruction came from a county inspector, but I may have misunderstood his instructions. Is this correct? In all this it appears that the neutral and ground are connected.
From a different inspector we were told and did run a house #6 ground. This ground is attached to the grounding strip affixed to the left side of the breaker box, through a connector attached to the 3 inch conduit inside (runs to outside meter box), and to the cold water supply
A separate neutral strip has been provided on the right side inside the breaker box.
Today we finished making up the breaker box. We attached Cu 2/0 from their correct hot positions in the outside meter box to the correct hot positions in the inside breaker box. The same with the neutral 2/0. We are fairly certain of the individual breaker and Arc Fault connections.
We tried the same male to male connection test as before, and the GFI at the street temporary service trips. We assume there is a short or the ground is bad.
Disconnecting the neutral 2/0 from both locations fixes the problem. The GFI no longer trips.
Of course we need the 2/0 neutral. Where did we go wrong?

Thanks much,
ronhert

 

I have to tell you most of that jumbles together and makes it harder to understand but I will comment on this to the best I can grasp it.

If you are doing a 200A service ( based on the 200A meter cab ) I will assume the panel is a 200A panel...please correct me if I am wrong....

OK based on that 2/0 is sized correctly based on Art 310-15(b)(6) if you are doing a 200A service as far as the HOTS lines go. Now how did you size your neutral because basically if you use individual wires through a conduit you need to know the service calculation to do this....2/0 should be fine for the neutral but you really need to view 220-22 and calculate the neutral to hot and determine the minimal neutral needed.

As for the grounds I have to ask....you stated the GC goes to a re-bar encased in concrete...this would be a encased electrode and would be a # 4 CU Bare as listed by Art 250-66(b) and the line to the waterpipe would be # 4 CU Bare as well.

On the ground from the panel to the meter cab ( which is not done that way in VA so I can't comment on that but is not overly explored in the NEC) as generally the neutral serves this purpose in the main installation itself.

Did you tell the inspector that told you to run #6 that it was to a Concrete-Enclosed Electrode?

As for the tripping of the GFCI....I can only think that the unit is feeding something in the house that is also feeding back to the panel and causing a short and tripping....check your connection from the GFCI into the house and make sure nothing is hooked to it......

Hope I have helped any......codes can be slightly different in some areas due to AHJ's ability to expand on issues.....but here are a few articles you can review in the Code:

Art 250-66
Art 250- 66(b)
220-22- Sizing Neutral

Hope this helps any....I did my best to understand the post. Also check again on that ground wire giong to the same terminal as the neutral in the meter cab....I dont like that idea and we dont do that in VA....if the Utility company wants a ground to their cab here...they run one to our GEC and tap it since they are not bound by NEC for the most part...and in some areas of VA we actually run the GEC to a ground rod and so on...and take it to the meter cab and not to the panel...yes I dont agree but inspectors in the area where the utility company wants it done that way approve it.

Pull that ground off the neutral in the meter cab and see if the GFCI stops tripping....

 

In the main panel the grounds should be bonded to the neutral by either a green screw or strap. I hope this is done.
If it is done this is what is tripping the GFI. You are creating a true ground fault by testing it this way.
Why, may I ask, are you testing the system this way with the panel all made up? Just curious.

The 2/0 you refer to I assume is copper. In this case 2/0cu is typically oversized for a 200 amp feeder neutral, but certianly not a problem. A neutral feeder calculation is not usually necessary for a residence as the load is typically balanced enough to let the neutral be undersized.

One thing that is wrong is the #6 to the water pipe. This must be #4cu. If there is metal pipe coming in for the water you must connect the #4 within 5' of where it enters the house.

I am surprised the inspectors are giving you so much advice. This is not their job and most are reluctant to do so, as they should be.

 

Petey,

The reason I tell him about sizing the neutral is that it is good to know and secondly he is running individual lines to the meter not a pre-sized SE or SEU and so on....based on what I read in the post....but again a bit jumbled to me.

lol....always better to have a oversized neutral if you can get away with it...due to Non-Linear Loads and Harmonics as you start to use more technical equipment and so on down the road....but again as said before might be overkill...I like my Neutrals slightly larger than the minumum..but thats me...

 

I guess I did the same thing.

I agree it was kind of hard to understand. Do you get the same impression as me with regard to the GFI tripping?

 

Yeppers my brother.....That is why I also wanted him to remove the place where he put the ground with the neutral in the meter cab...down here ( not sure everywhere ) we dont do that.

But yeah I would say the GFCI is reading back from a circuit that is causing it to trip.....at this point he should abandon the GFCI circuit...lol

If it was me and I dont know the job..I would simply take each BLACK or HOT wire with a CONT tester to the ground/neu bar.......if nothing....he is all set..lol...I dont think I would rely on a GFCI...lol

You are right on petey...That is what I think it is doing also.

 

Thanks guys for your help.
We know our questions jumble together a bit, but bear with us. At about 10:00hrs, we are on our way to the site to try your suggestions to correct this.
First, we will “check again on that ground wire going to the same terminal as the neutral in the meter cab.” We will “Pull that ground off the neutral in the meter cab and see if the GFCI stops tripping.”
Next, we will try to connect the ‘foundation’ ground to the ‘water pipe ground.“
Is there any way of testing circuits after the main panel is made up?
Please keep the help coming. We want it done right, so we will need to postpone our Electrical Service inspection until Monday or whenever it is done right. We will keep you informed as to status, and results. All’s well that ends well.
ronhert

 

Are you trying to test the entire panel through the GFCI service at the street? I you are doing what I think you are doing the GFCI should trip or it is bad. A GFCI breaker trips when it sees any current on the ground conductor. Since you are trying to test the main panel, the ground and neutral are tied together inside the panel. When you plug your "test cable" into the service side of the panel what you have done is essentially split the return current in half with your test cable - half down the neutral of the test cable and the half down the ground wire of the test cable which will trip the GFCI.

When you test the individual circuits you are testing at a point before the ground and neutral are strapped together, so the GFCI doesn't trip.

Is this right or did I misunderstand how you are doing this test?

 

Thx ElectricalMan, Speedy Petey, and Blizzad, and all for your help.
Review: We had ‘checked’ the circuits using a male to male plug in from our temp service before wiring the Meter & Breaker panel. All was OK.
Our E-Service = meter box w 200A disconnect feeding to breaker panel w 200A disconnect. Does this = sup-panel? 3 Feeders = Cu 2/0. Gnds = #4Cu bare to re-bar & Cu cold water pipe. I have a block diagram in powerpoint if you like.
When we tried to ‘re-check’ the circuits (same male to male) in from our temp service. It always tripped the GFI breaker at the temp service.
Your Suggested actions:
1 ElectricalMan: “The GFCI is reading back from a circuit that is causing it to trip. Abandon the GFCI circuit. Simply take each BLACK or HOT wire with a CONT tester to the ground/neu bar. If nothing. He is all set. Don’t think I would rely on a GFCI.” Results: A VOM shows ‘open’ between HOTs, and ‘open’ each HOT to ground or neutral. There is closed circuit between neutral & ground. We are going ahead with the inspection.
2 Speedy Petey: “In the main panel the grounds should be bonded to the neutral by either a green screw or strap. I hope this is done.” Results: It is.
3 “Check again on that ground wire going to the same terminal as the neutral in the meter cab. I dont like that idea. Pull that ground off the neutral in the meter cab and see if the GFCI stops tripping.” Results: When we undid the 2/0 white neutral feeder, and the ground connection in the meter box, the ‘test’ no longer tripped to temp breaker.
4 Blizzard: “trying to test the entire panel through the GFCI service at the street? (YES) A GFCI breaker trips when it sees any current on the ground conductor. Since you are trying to test the main panel, the ground and neutral are tied together inside the panel. When you plug your "test cable" into the service side of the panel what you have done is essentially split the return current in half with your test cable - half down the neutral of the test cable and the half down the ground wire of the test cable which will trip the GFCI.” Results: Thanks, we abandoned our ‘in-line’ test idea. When we “test the individual circuits (we) you are testing at a point before the ground and neutral are strapped together, so the GFCI doesn't trip.”
Since Monday is Presidents Day, a holiday, we requested ELECTRICAL SERVICE INSPECTION on Tuesday. We will keep you posted. Thanks again.
ronhert

 

Thanks again to ElectricalMan, Speedy Petey, and Blizzad, and all for your help.
We had our inspection today. He said we needed to add one Cu#4 connect from the outside meter box GND/NEUT strip to the case of the inside box, but otherwise we are OK. He said he would be back in a day or two with a green tag.
Lesson learned: Be sure of the 2 grounds (encased & cold water pipe), and be sure they are one together, and that in any sub-panel the grounds above are isolated from the neutral.
Thanks for your patience. We were in a state of ignorant panic.