grounding electrode conductor

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treyp3

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Fernandina Beach Fl
250.66(A)?
A practice test asks: what size GEC for 3/0 ungrounded service conductor to metal water pipe? answer-4awg cu.
Is this correct? If so, what does pipe mean in 250.66(A)?
Also, when we shifted from primarily using ground rods to primarily bonding to the slab some years ago we continued to use 6cu GEC for 3/0 al 200a services. No one has ever called me out on this, but I'm looking at 250.66(B) and I'm thinking it would require 4 cu GEC. Ideas?
 
roger

roger

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treyp3 said:
250.66(A)?
A practice test asks: what size GEC for 3/0 ungrounded service conductor to metal water pipe? answer-4awg cu.
Is this correct?
Click to expand...
Yes, see Table 250.66
treyp3 said:
If so, what does pipe mean in 250.66(A)?
Click to expand...
It means a driven 3/4" pipe, see 250.52(A)(5)(a)

treyp3 said:
Also, when we shifted from primarily using ground rods to primarily bonding to the slab some years ago we continued to use 6cu GEC for 3/0 al 200a services. No one has ever called me out on this, but I'm looking at 250.66(B) and I'm thinking it would require 4 cu GEC. Ideas?
Click to expand...
Your inspectors should be calling this a violation.

Roger
 
Dennis Alwon

Dennis Alwon

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I agree with Roger. I would use #4 to the CEE even on a 100 amp service simply because if they ever upgrade to a larger size the wire is appropriately sized.
 
kwired

kwired

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NE Nebraska
treyp3 said:
...Also, when we shifted from primarily using ground rods to primarily bonding to the slab some years ago we continued to use 6cu GEC for 3/0 al 200a services. No one has ever called me out on this, but I'm looking at 250.66(B) and I'm thinking it would require 4 cu GEC. Ideas?
Click to expand...

#6 Cu GEC is acceptable for 3/0 AL service conductors.

3/0 AL conductors are not acceptable for 200 amps. Even in Table 310.15(B)(6).
 
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treyp3

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Location
Fernandina Beach Fl
roger said:
Yes, see Table 250.66 It means a driven 3/4" pipe, see 250.52(A)(5)(a)

Your inspectors should be calling this a violation.

Roger
Click to expand...
Ahhh... metal underground water pipe vs rod and pipe, 250.52(A)(1) and 250.52(A)(5). Although it doesnt say driven I clearly see the distinction.
Soo embarassed about the 6 cu, glad I cleared that up hear where Im somewhat anonymous.
Thanks for the help guys! Will be shure to pick up some #4 bare!
 
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