Electric service wire

[toadjammer]

I need to put in new wire for my electric service it is presently a 100AMP panel, with 1.5" conduit run to it. When I looked at an older NEC book it appears that I can run #4 copper with thhn insulation. My concern is do I have to derate the wire because I am running it 35 ft from entrance head to service panel?
Thanks
Toad

 

[Charles (in GA)]

You are asking about running service entrance cable from a weatherhead to the panelboard? Where is the meter? Is this on a residence or the detached garage?

If this is for a garage and not a residence, Table 310.15(B)(6) does not apply and you would need #3 copper cable. If this is a service entrance or feeder directly related to supplying the residence, #4 would be acceptable per the table reference above.

35 ft is nothing and I would not get concerned about that short of a distance.

Charles

 

[toadjammer]

I have an inside meter 3 feet away from my service panel. This is the service on a garage and runs 35 feet from the weatherhead to the meter.