250.66(a)

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augie47

augie47

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I had someone pose a question in regard to 250.66(A) that looked at it in a different light from what I have previously thought.250.66(A) states:
(A) Connections to Rod, Pipe, or Plate Electrodes. Where the grounding electrode conductor is connected to rod, pipe, or plate electrodes as permitted in 250.52(A)(5) or (A)(7), that portion of the conductor that is the sole connection to the grounding electrode shall not be required to be larger than 6 AWG copper wire or 4 AWG aluminum wire.

He noted that the wording is singular ie: electrode
Quite often plans in this area call for the "tripod" of ground rods.
If you have multiple electrodes, such as in the "tripod", is a #6 cu still the largest conductor required ?
 
I'm betting someone spotted some boilerproof language and took the conservative route for liabilty in your area.

250.4(A)(2) and (3) reflect the actualities involved.

Two is a drain to the earth, three is about bonding back to the system to trip the OCPD.

Anyone out there have a copy of NFPA 780?

Per the NEC in 250.66(A) I'm staying with the call out of #6
 
It applies to each connection, one connection at a time. That is, if I have a wire, and connect it to an electrode (it being of the types listed), then that wire need not be bigger than #6. Show me another wire, and the point that it connects to another electrode, and that wire need not be bigger than #6 either. Ask about wire sizes as they pertain to one electrode at a time, and you will get the same answer each time.
 
Al conductor

Al conductor

I don't understand why they list the #4 Al conductor. It can't be terminated properly on 2 of the 3 listed electrodes according to 250.64(A).
 
Rockyd said:
I'm betting someone spotted some boilerproof language and took the conservative route for liabilty in your area.

250.4(A)(2) and (3) reflect the actualities involved.

Two is a drain to the earth, three is about bonding back to the system to trip the OCPD.

Anyone out there have a copy of NFPA 780?

Per the NEC in 250.66(A) I'm staying with the call out of #6
Click to expand...

What do you mean by "two is a drain to earth, three is for tripping the OCPD"?I have never heard that before.Can you explain the theory to me?
 
joebell said:
I don't understand why they list the #4 Al conductor. It can't be terminated properly on 2 of the 3 listed electrodes according to 250.64(A).
Click to expand...

You could use a 10' rod or pipe with 2' sticking out of the ground to accommodate the 18" minimum.
 
What do you mean by "two is a drain to earth, three is for tripping the OCPD"?I have never heard that before.Can you explain the theory to me?
Click to expand...

After 1234 posts, you'd think I'd learn not to assume...shame on me. :)

250.4(A)(2) Grounding of Electrical Equipment
Normally non-current-carrying conductive materials enclosing electrical conductors or equipment, or forming part of such equipment, shall be connected to EARTH so as to limit the voltage to ground on those materials.

250.4(A)(3) Bonding of Electrical Equipment
Normally non-current-carrying conductive materials enclosing electrical conductors or equipment, or forming part of such equipment, shall be connected TOGETHER and to establish an effective ground fault current path.

*An effective ground path, in the event of a ground fault, or short circuit, will facilitate tripping the breaker (or blowing the fuse).

See 250.4(A) in it's entirety. It'll make a lot more sense.
 
augie47 said:
He noted that the wording is singular ie: electrode
Quite often plans in this area call for the "tripod" of ground rods.
If you have multiple electrodes, such as in the "tripod", is a #6 cu still the largest conductor required ?
Click to expand...

Does the last paragraph in 250.58 do anything for you?
 
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