What size conductor should I use to bond the copper water main line? I'm using two ground rods on one continuous #4, and it is unknown on the length of the pipe outside of the home, so the connection is merely a "bond" rather than an electrode... I've still connected within 5 feet of the entrance with a listed pipe connector, but I've used #6 rather than #4. It is a 200 Ampere 120/240 Volt Residential Dwelling Service.

Should I pull the #6 and replace it with #4?

Guess 250.66 just has me perpetually confused...

Sparky,
For the water pipe, it doesn't matter if you are using it as a grounding electrode or just bonding it. The conductor is sized by the size of the service entrance conductors and Table 250.66. Fo a 200 amp service, #4 is the miminum for the connection to the water pipe and if your service entrance conductors are larger than 3/0 you would have to use a #2. The connection to the ground rod is never required by the code to be larger than #6. See 250.66(A).

If I'm using 4/0 Al, I can use #4 Cu, right?

I didn't know if the "rod, pipe or plate" part in 250.66(A) let me use #6 or not, 250.52(A)(1) Doesn't specify size...

250.53(C) points to 250.66, but I guess I'm caught up in whether it is considered a "pipe" electrode...

Remember, I have to tear out and replace something that most don't bother doing in the first place here... So, is #4 Cu OK, or do I have to use #2???

The #6 will get yanked but now I don't know whether to buy #4 or #2 Cu to replace it.

If I have to use #2, please show me how to arrive at the answer for future reference.

Thanks,
-Virgil

Sparky,
4/0 aluminum service entrance conductors require a #4 copper to the water pipe. The "pipe" electrode refered to in 250.52(A)(5) and 250.66(A)is a section of pipe driven into the ground like you would drive a ground rod. It is not a metal underground water pipe. This section, 250.66(A),only permits a reduced size grounding electrode conductor for what was called a "made" electrode in previous codes. That would be a driven rod, driven pipe or burried plate. The connection to the interior metal water piping system and the metal underground water piping system, if any, must always be sized per Table 250.66.
My reference to #2 would only apply if the service enetrance conductors were larger than 3/0 copper or 250 aluminum.
Don

Thanks Don, all clear now!



(Got plenty of #4 Cu, and it's only a 15 ft. run)