Feeding subs with 6 no. 6

Reply

  #1  
Old 05-13-04, 11:02 PM
Member
Thread Starter
Join Date: Jun 2002
Location: Brethren, Mi
Posts: 1,648
Received 0 Votes on 0 Posts
Feeding subs with 6 no. 6

As I read the table in 310.15 I believe they list 4 being good for 100A as a panel feeder. I see it quoted here that the 6 60 combination is acceptable as a feeder combination. Its not listed, but due to the next size rule is this acceptable?
 
Sponsored Links
  #2  
Old 05-14-04, 04:37 AM
Member
Join Date: Jan 2004
Location: Oregon
Posts: 1,219
Received 0 Votes on 0 Posts
Table 310.15(B)(6) cannot be used to size the feeder for a subpanel, unless that 'subpanel' is the _main_ panel for your home (eg. a 'subpanel' fed from a combination meter/main disconnect where all of the power in your home goes through that subpanel).

For subpanels, you generally need to use table 310.16. Usually you use the 60degree column, though sometimes you can use the 75degree column. #6 copper wire has an ampacity of 55A. It is commonly used for a subpanel feeder, and the 'round-up' rule is applied.

Note: the round up rule does _not_ say that you can use #6 wire to carry 60A. What it says is that you are permitted to _protect_ #6 wire with a 60A breaker. The load on the #6 wire is still required to be less than 55A (presuming 60C limitations). This is a point where the code is generally applied a bit loosely; people install a '60A' subpanel in a garage/workshop, with a #6 feeder, and don't bother actually doing the load calculation to make sure that the actual calculated load is less than 55A; they simply presume that it will be...and they are usually correct.

-Jon
 
Reply

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Thread Tools
Search this Thread
 
Ask a Question
Question Title:
Description:
Your question will be posted in: