GEC sizing

[fyrmnk]

Hi all. I looked at a home today with 200 amp service, 2/O copper feeding it. If I read the NEC correct, the GEC should be #4 unless going to a rod, then #6 is acceptable.

In this case, a #4 was going to a ground rod, and #6 was going to the main incoming water line (backwards).

I assume the #6 should be changed to #4 to be in line with the NEC even though there is a #4 to the rod. Is that correct?

Thanks in advance.

[hausdok]

Hi,

I think you're fine. The #4 GEC to the rod is what you're talking about. The #6 is a bonding cable.

OT - OF!!!

M.

[Richard Moore]

Gotta disagree there Mike...assuming this is recent wiring.

Then the main grounding electrode should be the metal water service (with a #4 GEC connected within 5' of where it enters the building). The ground rod is "supplemental" to the water piping (#4 or #6 fine).

[fyrmnk]

The house is 3 years old.

It is within 5' of where it enters as it should be.

Thanks.

[hausdok]

Hi Richard,

I agree to a point. The pipe entering the home has to be in contact with earth for at least 10ft. or more. Since one usually can't know for sure what there is below grade on the other side of a basement or crawlspace wall - more and more plastic supply lines seem to be appearing - I'm hesitant to rely on those for a ground and look for proper bonding and either a ufer or driven grounding electrode.

OT - OF!!!

Mike

[Jim Katen]

Originally posted by fyrmnk

Hi all. I looked at a home today with 200 amp service, 2/O copper feeding it. If I read the NEC correct, the GEC should be #4 unless going to a rod, then #6 is acceptable.

In this case, a #4 was going to a ground rod, and #6 was going to the main incoming water line (backwards).

I assume the #6 should be changed to #4 to be in line with the NEC even though there is a #4 to the rod. Is that correct?

Thanks in advance.

From your description, I think Richard Moore has nailed it. The wire sizes are ok.

I'm curious, though. Don't you guys use Ufer grounds down there?

In my area, *everything* built in the last 10 years or so has a Ufer ground.

- Jim Katen, Oregon

[Scottpat]

I seldom see a Ufer system in my area. I thought Ufer grounding systems were primarily used in areas with low soil conductivity such as areas with a low water table, sandy or rocky soil conditions.

[inspectort]

The NEC REQUIRES A #4 COPPER OR A #2 ALUMINUM TO THE WATER PIPE, MINIMUM. IF YOU ARE UNSURE IF YOU HAVE METALIC WATER LINES UNDERGROUND THIS WOULD BE, AT THE LEAST, A GOOD BOND FOR THE INTERIOR WATER LINES. The grounding electrode conductor from the service to the rod is never required to be larger than a #6 copper or #4 aluminum 250.66(A) but this is only a minimum, it can be larger. If you are unsure of a good ground, or their is no water ground at all, we require electricians to drive 2 rods and bond together. Two rods are also required where their is 25ohms or less resistance to ground.

[fyrmnk]

From your description, I think Richard Moore has nailed it. The wire sizes are ok.

I'm curious, though. Don't you guys use Ufer grounds down there?

In my area, *everything* built in the last 10 years or so has a Ufer ground.

- Jim Katen, Oregon

There are some Ufer ground systems here, most often though it is two ground rods and copper line coming in. Thanks for the responses.