Need to match 220v 7 amp motor to circuit breaker?

[Randall J Cox]

Just acquired an old Delta Rockwell 30 C radial arm saw. I will be totally rehabbing it this spring. It is set up for 220v, motor says 14/7 amps. I have an outlet in my shop that I can use that is 220v with a 40 amp breaker. Right now I use this outlet for my Delta 3 HP 15" planer. As I would not be using my planer at the same time I would be using the RAS, anything wrong with plugging my RAS into this outlet it for use? (As an aside, I had a larger sub panel installed a couple of years ago by an electrician.) Randy

[Mike Rambour]

nothing wrong with that. The breaker protects the wire in the wall not the tool. It will be fine, I run my SawStop on a 50amp circuit designed for my welder, I did make a 2ft long cord with 50amp plug and the plug for the SawStop (I think the SS requires 20) on the other end out of 10gauge wire since I could not change the 50amp plug on the welder.

[Tom M King]

There are millions of safe circuits operating with one 60w light bulb on a 15, or 20 amp circuit.

[Malcolm McLeod]

There are millions of safe circuits operating with one 60w light bulb on a 15, or 20 amp circuit.

I'll see your 60W and raise you a 4W night light.... or would that be "lower you"??;)

[Randall J Cox]

I thought I had read some time ago that we are supposed to "match" the circuit breaker to the motor being driven, no? Maybe I'm remembering this wrong.... Randy

[Frank Pratt]

I thought I had read some time ago that we are supposed to "match" the circuit breaker to the motor being driven, no? Maybe I'm remembering this wrong.... Randy

If it is a dedicated circuit to a hardwired motor, then you gotta go by what the code says. Here, you can have a breaker that is sized up to 250% of the motor FLA. That is to allow the motor to reliably start & not trip the breaker.

[Bruce Wrenn]

The breaker is to protect the wiring. The overload on the motor protects the motor. How many amps does your planer require? My 15" Delta (DC 380) with 2.0 HP motor runs on a 20 amp, 240 volt circuit.

[Rod Sheridan]

Randy, unless the manufacturer states otherwise, you're fine with the 40 ampere circuit.

I have 2 pieces of machinery which are limited to a 20 ampere circuit capable of delivering no more than 5KA short circuit current. Code requires you to follow manufacturer's information so in my case they are on a 20 ampere circuit........Rod.

[Bill Dufour]

The breaker is fine if you want to protect the motor you need a VFD or motor starter, with overloads, onboard the machine. Other countries use wall plugs with a small fuse. Look at your china made holiday lights to see what I mean.
Bill D

[Art Mann]

Most modern machinery uses motors which are internally thermally protected. They are built that way because it is impossible to design a cost effective breaker that will accommodate starting current and still protect the motor from steady state over-current such as you would have if a motor was accidentally stalled or otherwise mechanically overloaded.

[Randall J Cox]

Ok, guess its time to stop worrying. Thanks for all the insight and comments. Randy