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Joined: Feb 2001
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2017 NEC. 250.53(D)(2) requires a water pipe to be supplemented, and if by a rod, pipe, or plate, they must conform with 250.53(A). 250.53(A)(2) requires a single rod to be supplemented (except if it has a resistance to earth of 25 ohms or less).
Question: Is a grounding electrode system that consists of a water pipe and ground rod considered a 'single rod'? To put it another way, is 250.53(A)(2) applicable when the grounding electrode system consists of a water pipe and a ground rod?
Its been a while, glad to see many of the same folks still here!! Thanks all.
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Joined: Jul 2004
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The way I have always understood it a rod single rod that can't be demonstrated to have <25 ohm of ground contact is not an electrode but that may just be because we live in a sand box and we don't really trust rods that much anyway. I always see rods driven in pairs. That may also be that a rod is $15, 3-point (Fall-of-potential) test from an engineering company is a couple hundred bucks and arguing with an inspector is priceless 
Greg Fretwell
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Joined: Apr 2002
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Yes, as Greg so eloquently stated the FOP test up here is around $500.00, and the one that I know of failed the testing brutally. Arguing with me, or any other inspector is really not a good thing. Healthy discussion is fine and appreciated.
IMHO, two (2) rods are what the code states. Up here the the water mains are plastic for at least 80% or more. UFER s are installed when it's new work. Others are 2 rods, and another code compliant choice, plate, etc.
It looks like metalic water piping is going to join the other relics, like knob & tube!
John
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Joined: Jul 2004
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I think as ground ring is probably the most effective electrode if sparky gets there after the footers are poured but the price of the copper makes it cost prohibitive. The state put it in the bid for the toll booths and radio towers in addition to Ufers and rods. They wanted good grounds. The Ufer connection being made available is part of the 1&2 family structural inspection here so it ends up being pretty universal.
Greg Fretwell
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Thanks all. Per response from NFPA, a rod, pipe, or plate electrode that supplements a water pipe is considered a 'single' electrode and has to be 25 ohms or less to earth, or be supplemented. I guess I was just getting hung up by the term 'system' as used in 250.50; and offering the possibility that a 'system' of multiple electrodes might not be interpreted as a 'single' electrode.
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