25 amp tool on a 12 awg circuit

[Grant Morris]

Do you guys think it's safe to run a 25amp 220v tool off of 12 awg wire? 12 awg wire is rated at 20 amps and a 220 volt tool should only be pulling 12.5 amp on each hot wire.

TIA

[Ken Garlock]

NO, don't do it. A 25 amp rating means that there is 25 amps flowing in both wires, it is not divided between the two hot leads. Second, you don't want to put a load on a circuit that exceeds 80% of its max rating. This is a safety margin that should be observed. You need good old 10 ga. wire that is rated at 30 amps. Even with 10 ga. you are running on the edge of the 80% load rating.

[Michael Wetzel]

Nope. What breaker is installed on that #12?

[Gary Max]

Read Kens post again------it makes no difference what breaker you use if your running the wrong wire to degin with.

[George Bregar]

Read Kens post again------it makes no difference what breaker you use if your running the wrong wire to degin with.

It makes a lot of difference. If it has a 30A breaker, then the circuit is not protected. You can pull 30A. Which makes it a fire hazard. Which I think was his concern.

[Michael Wetzel]

Read Kens post again------it makes no difference what breaker you use if your running the wrong wire to degin with.

Maybe you should read my post again. My answer was "nope". I asked the breaker question to see if he has an unsafe situation he needs to deal with.

[John McClanahan]

220 volts, 25 amps means 25 amps on each wire. The machine needs a 30 amp 2 pole breaker and AWG 10 wire. In all reality, the machine probably draws a bit less than 25 amps, but not enough less to get by with 12 gauge wire.

John

[Bill Houghton]

I'd like to point out that everyone here is assuming that the circuit is relatively short. If it's long enough, even 10 ga. wire would not be enough. So, if the panel is in the shop, 10 ga. wire is fine; if it's all the way at the other end of the house, you could even need 8 ga.

I used to have one outside outlet, 20 amp circuit, in my house that required 10 ga. wire because the circuit length was enough that I needed to step up the wire size to avoid excess voltage drop.

And I concur, strongly, with everyone else: you're attempting to run too heavy a load on your wire size. You'll fry your circuit, trip the breaker all the time, or harm your tool's motor due to voltage drop; or some combination.

[Rod Sheridan]

It depends upon how much current the tool actually will be drawing, and whether the #12 AWG wire is properly protected by a 20 ampere breaker.

If the tool load is 16 amperes or less continuous, you will be fine.

If it is 20 amperes non continuous you will also be fine.

If it is 25 amperes short duration you will also be fine.

The 20 ampere breaker will have a thermal trip characteristic that will protect the #12 AWG, and 20 ampere receptacles from damage due to overload.

If you aren't tripping the circuit breaker, and are not exceeding 16 amperes continuous, you are fine.

Regards, Rod.