Another Grounding Issue/Question..

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stuartdmc

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Newport Beach, Irvine, CA
My question, I think is simple. If I can achieve 25 ohms or less by using the main ground rod, where in the NEC does it require me to provide a full size EGC to the cold water pipe? Can?t I pull a full size EGC to the rod and simply bond the W/P which is 100 ft. away with a #4?
 
I am not sure about a separate EGC to the cold. I have always bonded them with the ground rod. We are looking for redundant bonding. There are also local codes. #4 would depend on the size of panel.
 
If the water pipe can be consider an electrode(more than 10ft of metal ground) you must hit it within 5ft of where it enters the building. 250.52(A)(1). If you are just bonding it per 250.104(A) you can hit it anywhere you can make an accessible connection. Regardless it must be sized per 250.66.
 
The ground rod is a "made electrode". If the water is present, it is mandatory that you either bond to it, or use it as a grounding electrode.

250.53(D)(2) requires one to supplement the water if it is being used as the electrode.
 
Allow me make clarify, I have a 600A U.G.P.S. feeding a 400 and 200A service. Within the 400A meter section I have driven a 10ft. x ?? ground rod, (soil is very wet thus 25 ohms is achievable) I have ran a full size (3/0) to the ground rod, from the rod we ran 100ft. to the nearest cold water pipe with a #4 which is within 5 ft. of entering the BLDG. Questioning my installation, why would I need to pull a Full size GEC (3/0) to the cold water pipe?
 
mistermudd said:
If the water pipe can be consider an electrode(more than 10ft of metal ground) you must hit it within 5ft of where it enters the building. 250.52(A)(1). If you are just bonding it per 250.104(A) you can hit it anywhere you can make an accessible connection. Regardless it must be sized per 250.66.
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Is it more then 10ft. of metal pipe in the ground? of just 10ft. of copper pipe?
 
If it is a grounding electrode conductor it is sized per 250.66. If you are bonding the water 250.104(A)(1) tells you to size it per table 250.66. Either way you are stuck with table 250.66. Largest copper wire required to go to the ground rod is #6 250.66(A).
 
It is consider one of the electrodes to be included in the grounding electrode system if there is more than 10 ft. of metal water line in contact with the earth. Otherwise it is a metal water piping system that must be bonded.

As far as how much metal water pipe is considered a metal water pipe system, I think it is a judgment call. A piece of metal pipe used as a manifold to attach a bunch of plastic may not be considered a pipe system. Maybe someone else has some ideas on this point.
 
stuartdmc said:
My question, I think is simple. If I can achieve 25 ohms or less by using the main ground rod, where in the NEC does it require me to provide a full size EGC to the cold water pipe? Can?t I pull a full size EGC to the rod and simply bond the W/P which is 100 ft. away with a #4?
Click to expand...

Read the definition of equipment grounding conductor under Grounding Conductor, Equipment and then read the definition of grounding electrode conductor.
If you have a metallic pipe in the ground and the pipe is ten feet or more in length that is present at your project than it must be included in your grounding electrode system. This also goes for other items found at 250.50. Where 10 or more feet of metal pipe in the ground does not exist than 250.50 says to look at 250.52(A)(4) through (8) for what shall be installed.:)
 
And even if the water pipe is not a grounding electrode, the interior metal water piping system still requires a T250.66 sized bonding connection per 250.104(A)(1).
 
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