Material to wire 220 circuit

vhuffines · 10-29-2011, 08:35 AM

Hi,
I have two spare breaker slots in main 200 amp panel and easy access to it. I plan to wire a circuit for a saw. 3 HP motor,single phase, 18 amps. The wire run is 25 feet. Live in central Ky. Need to know wire size and breaker size. Thanks for your thoughts and answers.

Sine · 10-29-2011, 09:09 AM

General rule for motor conductor sizing is 125% of the full load current plus anything else like an inspection light. You'll probably want to run #10 and put it on a 2pole 25A or 30A breaker.

iminaquagmire · 10-29-2011, 09:10 AM

18A seems like a lot for a 3hp motor at 240v. That would be a pretty ineffient motor. Are you sure about the amperage? That would be about right for the motor if it was wired at 120v. But if it is right, wire size for this would be #10 on a 30A breaker. Your local codes may vary however especially in regards to the wiring methods allowed (i.e. conduit vs romex or AC/MC).

vhuffines · 10-29-2011, 07:54 PM

Thank you guys for your information. I think I will wire with#10 to 30amps.
Vernon

Speedy Petey · 10-29-2011, 08:31 PM

Quote:

Originally Posted by iminaquagmire

18A seems like a lot for a 3hp motor at 240v. That would be a pretty ineffient motor. Are you sure about the amperage? That would be about right for the motor if it was wired at 120v.

Your numbers are WAY off.
I'd guess it is a REAL 3HP motor, as opposed to something like a Craftsman "6hp" vacuum cleaner that only draws 15A @ 120v.

18A is pretty much dead on.

Check the tables at the end of Art. 430.