Ground rod(s?) at a residential outbuilding

[JDBrown]

I could have sworn I read somewhere that a residential outbuilding (shed, detached garage, workshop, etc.) supplied by a feeder only needs 1 ground rod, but now I can't find it.

I know you can get away with only 1 ground rod if you have another electrode at the structure (rebar in the footings, metal water pipe, etc.), or if you test the resistance to ground < 25 Ohms (NEC 250.56). But it seems like this was an Exception specifically for residential outbuildings, somewhere along the lines of the Exceptions in 225.36 and 225.38 allowing snap switches as a disconnecting means for residential outbuildings.

I've been searching through the NEC, but I can't find it anywhere, so I'm starting to think I must really be remembering things wrong. Does such an Exception even exist?

 

[petersonra]

it does not require a ground rod at all if it has a CEE.

the rules are basically the same as for the structure the feeder comes from.

 

[iwire]

I could have sworn I read somewhere that a residential outbuilding (shed, detached garage, workshop, etc.) supplied by a feeder only needs 1 ground rod, but now I can't find it.

I know you can get away with only 1 ground rod if you have another electrode at the structure (rebar in the footings, metal water pipe, etc.), or if you test the resistance to ground < 25 Ohms (NEC 250.56). But it seems like this was an Exception specifically for residential outbuildings, somewhere along the lines of the Exceptions in 225.36 and 225.38 allowing snap switches as a disconnecting means for residential outbuildings.

I've been searching through the NEC, but I can't find it anywhere, so I'm starting to think I must really be remembering things wrong. Does such an Exception even exist?

An outbuilding supplied by a feeder is required to have a full grounding electrode system. The rules are the same as for a service.

That could be just one ground rod if you could prove less than25 ohms resistance.

 

[CONDUIT]

Look at 250.32.

 

[Little Bill]

Our inspectors only require one ground rod at a detached structure on residential property.

 

[iwire]

Our inspectors only require one ground rod at a detached structure on residential property.

That's interesting but not the NEC unless that single rod ends up under 25 ohms.

I put two rods at temp services.

 

[JDBrown]

Thanks for the input, guys. Looks like I was just off my rocker on that one. Two rods it shall be.

 

[Little Bill]

That's interesting but not the NEC unless that single rod ends up under 25 ohms.

I put two rods at temp services.

I guess they are just using common sense, NEC aside.

 

[jumper]

I guess they are just using common sense, NEC aside.

Common sense and using the NEC is not allowed.

 

[GoldDigger]

Common sense and using the NEC is not allowed.

Actually, common sense in design (not covered by NEC) is not only allowed but expected.
It is only when you want to do less than the NEC requires (or appears to require) that common sense is outlawed. I can see the bumper stickers now....