how many ground rods?

[Stevenfyeager]

Some Utilities in S. Indiana require only one ground rod, some two. Where in the NEC is this? I've looked in 250. Some say two grounding electrodes; one rod, plus one other one like a metal water line, or two rods. 400 amp house service. Thank you.

 

[480sparky]

Utilities aren't driven by the NEC. They can make their own rules. But 250.53(A)(2) Exception is what you're looking for.

 

[augie47]

Keep in mind that utilities can make their own requirements. We have several in this area that require a ground rod even when one is not required by the NEC,
250.52 list a ground rod as one of the permissible grounding electrodes.
250.53 discussed when a supplemental electrode is needed. (when one rod can't provide 25 ohms or less, or when a metal underground water pipe is your electrode)
Often a ground rod is used for the supplemental electrode

 

[JDB3]

In Texas, when I bond/ground to the re-bar in the slab what size bare wire is needed? I had always thought #6 ?
:?

 

[petersonra]

In Texas, when I bond/ground to the re-bar in the slab what size bare wire is needed? I had always thought #6 ?
:?

demands on what the table says. It never has to be larger then #4 though.

 

[tom baker]

Section 250.66, see either A, B or C.

 

[Stevenfyeager]

Keep in mind that utilities can make their own requirements. We have several in this area that require a ground rod even when one is not required by the NEC,
250.52 list a ground rod as one of the permissible grounding electrodes.
250.53 discussed when a supplemental electrode is needed. (when one rod can't provide 25 ohms or less, or when a metal underground water pipe is your electrode)
Often a ground rod is used for the supplemental electrode

Thank you.