Sub Panel


Old 01-23-00, 05:48 AM
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I'm planning on adding a sub panel to my garage. I'm figuring on
using a 100 amp, 6 circuit panel. I can't imagine that I would be
drawing more than 30-40 amps at any given time with just lights, radio,
compressor, and one power tool at a time. I assume I connect the sub to
my main with a 240 breaker, correct? What size? What size wire should I
use for a 15-18 foot run between the panels? Would it be a good idea to
use a GFCI breaker in my main panel for the sub main (if so, what size?), or just GFCI
breakers in the sub panel? Thanks for any advice!!
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Old 01-24-00, 01:17 AM
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hi mike,
ok yes u install a 240 breaker, i would put in a 100 amp and pull in #4 wire this is good in a home 4 100 amps as a feeder which is what u r doing, this provides room 4 future expansion shuld u decide 2 add a welder or such, the cost of the wire wount be that much more and breakers r abought the same as well. as to installing a gfci as the feed breakeer i wouldnt. i wouldnt even install gfci breakers i would put gfcis in the first outlet on each circuit that u r installing outlets and feed the others its much cheaper this way. also i would put nothing smaller than 20 amp circuits on the outlets which requires #12 wire and 15 on the lighting which is #14, noo need to gfci the lighting. also in your sub panel dont bond the ground bar and the nutural together (ie puting a piece of wire between the nutural and ground or the bonding clip between the nutural and panel)
Old 01-25-00, 05:04 PM
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A 100 amp service will require a #3 rated wire whether it is THW or THHN.
Old 01-25-00, 10:46 PM
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david yes according to tabel 310-16 of the nec u need #3 but according to note 3 of the ampacity tabels in a 120/240 singel-phase deweling # 4 is rated 100 amps
Old 01-26-00, 05:03 PM
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Note three is not applicable. This is a sub panel. It is not either the service entrance nor the feeders to the main panel (wires after a main disconnect at the meter for example) A sub panel is a branch feeder and cannot be derated.
Old 01-26-00, 11:08 PM
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well thats what i origionaly thought as well. but the people i work 4 had me do it on a home and i ? it at that time, also asked inspector here, he said it was ok 2 do it it was in how the code is interpertiped.........not saying u r wrong nor am i saying im right
Old 01-27-00, 06:34 PM
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Hey Sprky,
That's 90-c. What they say goes.
Trouble is, you never really know what that is.

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