Wiring for A/C 40 amps--40 feet

[schaefage]

I am wanting to run electrical wiring which will handle 40 amps and run a length of 40 feet (through an indoor soffit) for my air conditioner. Can anyone tell me what guage wire to use to be safe in this situation. Is there a chart on the internet which can tell me this specifically? I looked at some charts and they either didn't have the right units or the correct distance. Thanks for your help.

Kent

[Rich]

Here's one - scroll down a little
http://www.powerstream.com/Wire_Size.htm

[Vector]

That's a pretty good reference, though the "Chassis Wiring" column could be eliminated for most purposes and make things clearer to the newbie. The numbers also don't agree with the 2002 NEC I have here...

The simple answer is 8 ga wire, three current carrying conductors plus a ground. If you buy it in a nonmetallic-sheathed "NM-B" (aka "Romex") wire, you're looking at "8/3" cable.

You will have to install a disconnect at the point where the wire leaves the house, and from there run liquid-tight conduit to the A/C unit itself. Often you can get pre-made whips of liquid-tight flex conduit with the appropriate conductors already inside for pretty good prices.

You should not run the sheathed NM-B in the conduit. Nor should you strip the sheathing off and run the individual conductors in the conduit. The conduit should have THWN wire, which you will have to buy by the foot if you don't go the pre-made whip route.

[Rich]

I believe that's what I used for my run too Vector. About 15' 60amp - or maybe it was 6 gauge - oh well - been too long ago. Used the same configuration you just described - seal-tight from panel to a disconnect at a/c unit.