what gauge wire

[Bob Mantica]

I just purchased a used dust collector I'm not sure what gauge wire I need to run from he panel to the plug.
it's a 3hp motor it draws 18 amps wired for 220 volts.

[George Bregar]

10g on a 30 amp circuit

[Bob Mantica]

Thank you that's kind of what I thought but I wasn't sure.

[Curt Harms]

You can use 10 ga., you don't have to. I'm pretty sure 12 ga. is good to 25 amps on a motor. A 20 amp circuit should be adequate unless the DC's manual specifies otherwise. What may matter is the circuit breaker. Some seem to be motor rated and will tolerate brief loads in excess of their rated amperage, others are not and will produce nuisance trips. A 3 h.p. dust collector will probably have a starting amp. spike of around 40 amps, maybe more. Do you need a 40 amp circuit? No.

[Rob Russell]

... I'm pretty sure 12 ga. is good to 25 amps on a motor ...

The only time #12 is good for 25 amps is if it's individual conductors like THHN/THWN run in raceway (conduit). #12 NM cable ("Romex" is a brand of NM cable) is only rated for 20 amps.

[Curt Harms]

The only time #12 is good for 25 amps is if it's individual conductors like THHN/THWN run in raceway (conduit). #12 NM cable ("Romex" is a brand of NM cable) is only rated for 20 amps.

Thanks. I wonder about use as an extension cord where the cable is not enclosed in a wall. Either way, 12 ga. is adequate for an 18 amp load, isn't it?

[Callan Campbell]

Thanks. I wonder about use as an extension cord where the cable is not enclosed in a wall. Either way, 12 ga. is adequate for an 18 amp load, isn't it?

Curt, I wouldn't think so from a protection standpoint. You're so close to the max nominal rating of 20 amps for a 12 gauge circuit, even if it was indiv. wires like Rob pointed out in a conduit and you're bumped up to a 25 amp rating. Why take a chance, just run 10 gauge and the correct cicuit breaker and be done with it. This way you have some tolerance room for aging or other issues built into the circuit and you're not maxed out like using 12 gauge wiring would leave you.

[George Bregar]

The cost to run a 10 gauge 30A 240V circuit versus 12/20 is a few bucks more unless it's a long wiring run, which needs to be the 10/30 anyway. I really don't get some of these responses...

[Steven Wayne]

The other variable that has not been given much mention is the length of the run.

[Curt Harms]

The other variable that has not been given much mention is the length of the run.

Yeah, for some reason I was thinking this was from an outlet to the saw.

[George Bregar]

Yeah, for some reason I was thinking this was from an outlet to the saw.

It's not from an out let to the saw, it's a circuit for a new dust collector.