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Monday, March 6, 2017

Question:

Is it permissible to parallel 600 Al. XHHW-2 for service entrance conductors on a 800 amp service?

Roger Gillam

A

Answer:

Hey Roger thanks for your question. No. If there are no adjustment or correction factors the 600 kcmil aluminum conductors have an ampacity of 385 in the 90 degree column of Table 310.15(B)(16). But the ampacity must be determined based on the termination temperature limitations as stated in 110.14(C)(1)(b) which is 340 amperes in the 75 degree column, unless the equipment is listed and identified for a higher temperature. With two parallel conductors that would be 680 amperes so you could use a 700 ampere overcurrent device based on 230.90(A) Exception No 2 if the load was not more than 680 amperes.

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