Is a 20 ft bare #2 AWG in the ground 30 in. deep connected to a nema 3 panel a ground ring according to code?

Question

I missed the cold water ground because they used plastic tubing. I missed the concrete encased because the slab was poured already. Tried to get by with just a ground rod, AHJ would'nt accept. Never ran a ground ring before. Am I on the right path?

Answer 1

250.52 A 4
says encircling the building at least 20 ft bare #2 AWG
check with ahj about using 2 ground rods ,,this may be used for existing slabs
just a wireman

ps
do you have a copy of 2005 nec

ps2
search for ---mike holt,,,go to forums then search--they are kind of uppity about people asking questions but a lot of info can be had just by searching

found on mike holt


I'm looking for claification of Sec 250.52 (4). A colleauge is interpretting it as you only need 20' of wire to make a ground ring. I see it as the conductor needs to go around a building, but only 20' is required to be bare. Can anyone clarify?




Not only encircle the building but 30 inches deep. A ufer is far better at essentially no cost.
__________________GOOD LUCK

Answer 2

You will need to encircle the building with a copper bare wire as you stating.

The end of the loop is twisted and soldered together at the tie right above ground, and not below, and is exposed above ground, and then a single#2 run and connected to your panel ground bar inside the box. This fullfills the requirements of the NEMA code and most municipal inspection requirements that I know of.

If you are using a metalic conduit such as underground service, you are also be required to ground out that conduit with a seperate wire run from the ground bar to a bushing on that pipe which has a ground screw hole and lock nut to accept a #2 wire ground. Such a bushing is available.

And a #2 is just fine. On depth, you are not looking for a total conductance such as is required on a ground rod, so a 30 inch trench is just fine too.

Dont be too angry about the extra work. I had a lightening problem that struck my AC once and my water well another time. The solution was a loop of #2 copper wire run in a loop around my entire residence and since then ive had zero problem with lightening strikes.

Answer 3

We use a 10 ft length of 3/4" rigid conduit driven into the ground for the earth ground. We hammer one end closed, drive in the ground and when the inspector comes out, he has a line with a weight on it and drops it down the conduit and he has a mark on the string at 10ft. so he knows if you drove the whole thing in the ground. We then clamp on the ground wire. and cover with earth or asphalt or concrete.

Answer 4

As long as you are 5 ohms or less when the inspector tests then you should be all right. You might want to rent a 'Megger' meter and check for yourself before you have an inspection done.

Answer 5

yes