Cut and dried?

[smallfish]

A service entrance cable with three 4 AWG Copper conductors was chosen by the electrical contractor to replace the original service entrance cable at a single-family dwelling. When making the inspection, I noticed that the old split-bus Federal Pacific NoArk Service panel was rated 125 amps.

2005 NEC 230.42(A) states, in part, that the ampacity of the service entrance conductors be determined from 310.15.
Table 310.15(B)(6) lists the conductor type and size for a 125 amp service to be 2 AWG Copper.

Must I require the contractor to upsize the service entrance cable or downsize the service panel or is the use of 4 AWG copper supplying a 125 amp-rated panel allowed somewhere in the NEC.

Thanks

 

[iwire]

Doesn't a split bus panel have more then one service disconnecting means?

If yes Exception 3 to 230.90 will be applicable and the conductors may be sized for only the calculated load and not the total ampacity of the service disconnecting means.

 

[iwire]

Table 310.15(B)(6) lists the conductor type and size for a 125 amp service to be 2 AWG Copper.

For what it's worth a dwelling unit service may use Table 310.15(B)(6) but it is not mandatory.


The contractor may elect to use 310.16 and apply all the rules and exceptions such as 240.4(B) and 230.90 Exception 3.

 

[smallfish]

I cannot begin to tell you how grateful I am to all of you who are so willing and capable in answering my questions on this forum.



As always, thanks