Can I run 3/0 copper se cable wire with the ground to a sub panel straight from the 200 amp breaker box to the 100 amp box through a crawl space without any conduit?
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1WHY are you running 3/0cu to a 100A panel???– Speedy PeteyCommented Nov 11, 2015 at 23:00
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2 Answers
From the 2011 NEC 310.15(B)(7) table. A 100 amp residential panel only requires #4 copper or #2 aluminum. 3/0 copper would be a waste of money.
If you use SE cable you will need 3 insulated conductors along with the bare wire.
338.10(B)(2) Use of Uninsulated Conductor. Type SE service-entrance cable shall be permitted for use where the insulated conductors are used for circuit wiring and the uninsulated conductor is used only for equipment grounding purposes.
Since you a using it for a feeder to a sub-panel you have to have an insulated neutral and use the bare for the equipment ground.
Do not bond the neutral and ground in the sub-panel and keep the neutrals and grounds separated. You need a panel that is "suitable for use as service equipment" since it will have an insulated neutral bar. Discard the green bonding screw.
Happy Friday!
Yes, as long as you are sure that it cannot not be "...subject to physical abuse..."
Also, you can't use it underground (even in conduit).
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Thanks that's great. Now I chose to use copper sense 1 panel the 200 amp will have connections (100)amp breaker then a 2' run to the crawlspace and then another foot out into the basement and to the sub panel so copper is required. Aluminum is way cheaper . is copper a better choice? Commented Nov 11, 2015 at 22:52
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@SteveHowerton, what makes you think copper is required? Commented Nov 11, 2015 at 23:01
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I am only aware that SE cable is required to feed a box. I also know that aluminum can corrode and get hot. I am not aware of any calculation to determine wire size. If aluminum is actually okay that would be great because I will be adding an additional sub-panel to handle a smaller 60 amp panel that will have to run through joist on a 15 ft run. I just was assuming copper would be safer. Thanks. Commented Nov 11, 2015 at 23:19
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I would use 2/0 or maybe even 1/0 for the 100 amp panel. No need to go all the way to 3/0. I believe 4/0 copper is good to like 200 amps or something, and the gauges increase by 10% each step, so you could go all the way to 1 gauge if you wanted to, but I would go 2/0 or 1/0.– DanielCommented Nov 12, 2015 at 1:46
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I used 4/0 aluminum for the weather head to the main breaker panel 200 amps. On the last service it was 3/0 aluminum. I just thought that was standard. I will research and price 2/0 copper. Thanks for the info. Commented Nov 12, 2015 at 3:30