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.
[OP]
Member
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.
Member
10g on a 30 amp circuit
[OP]
Member
Thank you that's kind of what I thought but I wasn't sure.
Contributor
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.
Member
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.Originally Posted by Curt Harms
Contributor
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?
Member
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.
Member
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...
The other variable that has not been given much mention is the length of the run.
Contributor
Yeah, for some reason I was thinking this was from an outlet to the saw.
Member
It's not from an out let to the saw, it's a circuit for a new dust collector.
Guest
And the answer is:
10 ga wire with a 20 amp breaker. 10 ga because it is big enough, with a little extra in view of the ability of most dust collectors to go over current when no hose is installed. And 20 amps to protect the wiring of the dust collector, which is probably less than 10 ga. As George mentioned, wiring is not the place to cheap out.
And my answer is:
10 ga wire with a 25 amp 2 pole breaker. A 20 amp breaker is only good for a 16 amp load (80% of the rated circuit load). If you can't find 25 amp breakers, 30's will do. Your mag starter provides motor overload protection. Your breaker provides wire overload protection. You do have a mag starter right?
Member
220v dictates a double pole breaker my guess is you will be hard pressed to find a 25 amp breaker and a 20 amp isn't big enough as was pointed out above so you are likely going to end up with a 30 amp breaker
this is not a place for cutting it close use the 10ga wire and the 30 amp breaker and save the fire extinguishers for something you can't control
to add to what George already said the cost to use the correct wire and breaker is not alot more than to use the wrong stuff initially and potentially is alot less when you factor in the fire hazard you would create by using wire and breakers too small for the intended use
rememeber , to paraphrase Smokey Bear, only you can prevent shop fires !!! be safe everyone the people who love you will be happier
Last edited by Don Alexander; 09-05-2011 at 1:02 AM.
[OP]
Member
The length of the run is approx. 50ft. I went with the original suggestion of 10 gauge wire and a 30 amp breaker. I felt the extra expense was worth having the extra margin of safety.
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