# Sizing Service and Feeder conductors...



## Dennis Alwon (May 9, 2009)

I would bet most contractors use T. 310.15(B)(6) for residential services. This is an exception for dwellings based on diversity of the loads in a dwelling.
We all use it because it is legal and more economical. Chicago may have an amendment to it, I don't know.


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## sparks134 (Jan 30, 2009)

Is there anyone out there that uses Table 310.16 to size service/feeders?


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## sparks134 (Jan 30, 2009)

Is there anyone out there that uses Table 310.16 to size service/feeders?


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## 4Runner (Apr 4, 2010)

sparks134 said:


> Is there anyone out there that uses Table 310.16 to size service/feeders?


Sure, all the time. Just not for residential services.


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## sparks134 (Jan 30, 2009)

Can you tell me why?


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## 4Runner (Apr 4, 2010)

sparks134 said:


> Can you tell me why?


Why do something you don't have to?


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## sparks134 (Jan 30, 2009)

My question is: 

I'm looking in the NEC 08 and Chicago Codebook (Both the same):

When sizing our service and feeder conductors for single phase dwelling we always size them according to Table 310.16. I was taught this way from the beginning, I never worked for a contractor that uses 
Table 310.15(B)(6). Who else does this and why? I ask EC and instructors they don't have an answer either. Why?
__________________


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## 4Runner (Apr 4, 2010)

sparks134 said:


> My question is: Why don't you use table 310.15 (B)( 6)???



I just said that I did. THINK, MAN, THINK!!!


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## sparks134 (Jan 30, 2009)

Ok, I just explained Two tables, so which table do you use?


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## 4Runner (Apr 4, 2010)

sparks134 said:


> Ok, I just explained Two tables, so which table do you use?



Don't go back and edit a post that's already been quoted. Just create a new one instead.


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## Dennis Alwon (May 9, 2009)

Sparks, I think both us answered your question. Do you want to know why T. 310.15(B)(6) is allowed for dwelling? If so I explained that the types of loads in a dwelling were diverse enough that basically they allowed for an exception for dwellings. 

This has been allowed for dwellings ever since I can remember. No, I don't use T.310.16 for service conductors on a dwelling. Why pay for 3/0 copper when I can get by with 2/0 copper on a 200 amp service?


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## sparks134 (Jan 30, 2009)

Ok! Thanks


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