# ampacity



## HARRY304E (Sep 15, 2010)

yetti said:


> What size aluminum SER cable do you need to feed an 100 amp sub panel in a residence?





Take a look at 310.15(B)(7) table...#4 copper..:thumbup:


Welcome to the forum you will have fun here and learn something too...:thumbsup::thumbsup:


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## erics37 (May 7, 2009)

HARRY304E said:


> Take a look at 310.15(B)(7) table...#4 copper..:thumbup:


He said aluminum, Harry :laughing:


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## nitro71 (Sep 17, 2009)

That table only applies if the panel is on the main feeder to the unit.


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## BBQ (Nov 16, 2010)

Harry is drunk.:laughing:

Depending on which year NEC you are on (and your main service conductor size) #1 AL or 1/0 AL.


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## backstay (Feb 3, 2011)

yetti said:


> What size aluminum SER cable do you need to feed an 100 amp sub panel in a residence?[/quote
> 
> Table 310.15(B)(7) for full unit(as an apartment)


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## BBQ (Nov 16, 2010)

backstay said:


> Table 310.15(B)(7)
> 
> #2 AL


In most cases you cannot use Table 310.15(B)(7) to supply a sub panel, you would have to use Table 310.16.


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## backstay (Feb 3, 2011)

So the question is, what is the sub panel feeding, an apartment or a guest house or a panel to add spaces for expansion?


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## backstay (Feb 3, 2011)

BBQ said:


> In most cases you cannot use Table 310.15(B)(7) to supply a sub panel, you would have to use Table 310.16.


The 2011 book has no 310.16 anymore, table is 310.15 now. Our continuning ed classes are on the 2011 NEC now.


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## Mr Rewire (Jan 15, 2011)

backstay said:


> So the question is, what is the sub panel feeding, an apartment or a guest house or a panel to add spaces for expansion?


 Read 310.15 (B)(6) in the 08 code they clarified that the use of table 310.15(B)(6) only applies to conductors carrying100% of the dwellings deversified load.


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## BBQ (Nov 16, 2010)

backstay said:


> The 2011 book has no 310.16 anymore, table is 310.15 now. Our continuning ed classes are on the 2011 NEC now.


Thanks, I have the 2011 beside me but did not notice 310.16 was now .15


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## don_resqcapt19 (Jul 18, 2010)

BBQ said:


> Thanks, I have the 2011 beside me but did not notice 310.16 was now .15


Not exactly, what was T310.16 is now 310.15(B)(16). All of the ampacity tables are 310.15(B)(xx), with the xx being the .(xx) in the 2008 code.


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## racerjim0 (Aug 10, 2008)

And ya'll wonder why some people (like me) can't recite codes!


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## jwjrw (Jan 14, 2010)

He asked what size SER he would need to run for a sub panel. BBQ had it correct. 1/0 is good for 100A at 60 degrees.


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## Speedy Petey (Jan 10, 2007)

jwjrw said:


> 1/0 is good for 100A at 60 degrees.


I'm sorry, while I realize this is the true code today, for YEARS we ran #2AL SER to a sub-panel. It is (still) good enough for a main feeder, yet it is more than two sizes to small today for a sub-panel. Pathetic. 

Anyone EVER hear of ANY issues with running #2AL SER to a 100A sub-panel???? Grrrr. 

Oh well, live by the code, I know.


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## HARRY304E (Sep 15, 2010)

BBQ said:


> Harry is drunk.:laughing:
> 
> Depending on which year NEC you are on (and your main service conductor size) #1 AL or 1/0 AL.


Mabe i was..:thumbup::laughing::laughing:


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## yetti (Feb 27, 2011)

Thanks for all the input, I am going off of 2008 code, and the sub-panel does supply 100% of the dwelling units load, so it is considered the main feeder. So according to 310.15(B)(6) I am allowed to use a #2 XHHW SER CABLE to feed the panel with 100 amps.


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## HARRY304E (Sep 15, 2010)

yetti said:


> Thanks for all the input, I am going off of 2008 code, and the sub-panel does supply 100% of the dwelling units load, so it is considered the main feeder. So according to 310.15(B)(6) I am allowed to use a #2 XHHW SER CABLE to feed the panel with 100 amps.


Yes that is right if you are going by the 2011 NEC it would be table 310.15(B)(7) That is the only differnce..:thumbsup:


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