What wire gauge for a sub panel 100a sub panel off a 200a sub panel?

Answer 1

4 gauge AWG copper minimum. Use this:
http://www.electrician.com/vd_calculator.html
I found this invaluable when wiring our outbuildings. This one puts out the wire size:
http://www.alternate-energy.net/voltlosscalc03.html

Answer 2

It is illegal for you to do this yourself and the power company won't reinstall your meter if you do. Call an electrician. Because of the danger of a fire for an improperly sized service cable , you should seek the advice of a certified electricion, or your local electric provider or an employee in the electric dept. in a home improvement store.

Answer 3

number six wire is good for sixty amps max Added by maintain... First, I am assuming that you are not an electrician. Second, I would suggest that you check with your local building official, it sounds like you may need a permit. Third, #6 THHN conductors will work under optimal conditions. However, there may need to be some deration factors applied. THHN may not work if the conductors are exposed to light, are installed in wet locations or other situations. It is best to check with a qualified electrician or local building official before you invest time and money on a project that will not work the way you want. Best of luck! Terry

Answer 4

That is quite a distance for a sub panel. 2/0 Aluminum would be the correct wire size. If for another building, a 100 amp service with it's own meter would be more practical and probably cost less. You would need a meter&pan, main box and service stub for the utility company to connect to. 275 feet of 2/0 service wire is going to cost you several hundred dollars alone. If you plan to get there underground, that is a big expense. Over head, you would need at least 4 support poles. (probably 6--max 50ft between poles for correct support plus strand guy wire to support cable.)

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A utility company will only allow one 120/240 volt drop to each property. A 4/0 aluminum conductor will limit the voltage drop to 3% or less when supplying 100 amps for 275 feet on a 240 volt system.
A 1/0 copper conductor will limit the voltage drop to 3% or less when supplying 100 amps for 275 feet on a 240 volt system.
When connecting a 100 amp sub panel check to see if the panel is 100% rated for 100 amps. Many are only rated for 80% capacity. If this is the case then the wire should be sized for 80 amps.

A #1 copper conductor will limit the voltage drop to 3% or less when supplying 80 amps for 275 feet on a 240 volt system.
RWU90 cable is direct burial but needs protection where it comes out of the ground to the panel. Also in the 100 amp sub panel you would need a #6 copper ground wire, 2 ground rods or a 2'x2' ground plate, buried 3' deep.

Answer 5

A #3 copper wire insulation rating of 90 degree is rated at 105 amps.

Answer 6

#3 copper wire if it is very close by.

Answer 7

In copper 2/0 (2 Ought)

Answer 8

NEC 310.16

#3 Thhn Copper