Grounding Electrode Conductor

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Yes.

However, you can reduce the service conductor size say from meter pan to the service disconnecting means (assuming both are in close proximity), and then run a "normal-sized" GEC(s) to the disconnecting means.
 
Smart $ said:
Yes.

However, you can reduce the service conductor size say from meter pan to the service disconnecting means (assuming both are in close proximity), and then run a "normal-sized" GEC(s) to the disconnecting means.
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Smart table 250.66 states that we must use the size of the largest service conductor. I don't see how reducing the conductors from the meter to the panel would change that.
 
Dennis Alwon said:
Smart table 250.66 states that we must use the size of the largest service conductor. I don't see how reducing the conductors from the meter to the panel would change that.
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I agree that it goes to intent as opposed to literal interpretation.

Consider for a moment that the reduced size service conductor from meter pan to SDM is a tap (and there is a hypothetical second SDM in a separate enclosure). The GEC is based on the size of the service conductor taps supplying the SDM [250.64(D)(2)].

JMO
 
Yes but you would need one grounding electrode conductor from each panel. The equivalent in most cases will be the same as the one sized for the service. I did a scenario where there could be 600-1000 kcm copper for a 400 amp service and the grounding electrode conductor would be 2/0. Two 200 amp panels would req. 2 #4. If you look at the amp of two # 4 at 75C we get 170 amps. The 2/0 gives us 175 amps.

I do see you point and I believe this may need a clarification in 2020.
 
Dennis Alwon said:
Smart table 250.66 states that we must use the size of the largest service conductor. I don't see how reducing the conductors from the meter to the panel would change that.
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That is where I was coming from. I have 750 Aluminum paralleled for a 400 amp service. Which is 2/0 copper. Didn't see how I could go less.
 
If you run 500 aluminum from transformer to meter socket (long run) and then run 4/0 aluminum from meter socket to 200 amp service disconnecting means inside a house - and land the GEC in the service disconnecting means do you size it for the 500 or the 4/0?

I would size it for the 4/0 service entrance conductor unless someone convinces me it must be sized to the 500 underground service conductor/lateral.
 
kwired said:
If you run 500 aluminum from transformer to meter socket (long run) and then run 4/0 aluminum from meter socket to 200 amp service disconnecting means inside a house - and land the GEC in the service disconnecting means do you size it for the 500 or the 4/0?

I would size it for the 4/0 service entrance conductor unless someone convinces me it must be sized to the 500 underground service conductor/lateral.
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I agree with you. My meter is at the road so my 750s are service entrance conductors.
 
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