Breaker size for Powermatic 5HP planer

[Alan Heffernan]

Just bought myself a new PM 20" planer and may need to put in a new circuit. My 220V circuits in my shop are 20 amps and I have one 30amp for my welding machine.

What breaker should I use with a 5hp motor? I have space in my panel for an additional 220v circuit and I will run some new conduit and wire.
Alan

[Tom Veatch]

It really depends of the full load amperage of the motor. But if you want to avoid potential problems run a 30 amp circuit with 10ga wire and 30amp receptacle (NEMA 6-30). You could probably get by with 20 amp 12ga wire, but on tasks where the full 5HP is developed for an extended time you could be subject to nuisance tripping of the breaker.

An alternative to running a new circuit would be to add a 30 amp receptacle to the existing 30amp circuit if that's convenient. It's doubtful you would be welding and planing simultaneously.

[Jim Mims]

Just bought myself a new PM 20" planer and may need to put in a new circuit. My 220V circuits in my shop are 20 amps and I have one 30amp for my welding machine.

What breaker should I use with a 5hp motor? I have space in my panel for an additional 220v circuit and I will run some new conduit and wire.
Alan

NEC Table 430.248 lists a 5 hp, single phase A/C motor at 28 amps.
Your nameplate rating will most likely be a little less.
If you go strictly by the national electrical code, the circuit would be required to be sized for 125% of 28 amps, or 35 amps.

You didn't say how far the run is (voltage drop considerations), but I'd run #8's and use a 40 amp circuit breaker. The code will allow you to use up to a 70 amp circuit breaker on this circuit.
- Jim
- Jim

[Johnny Fischer]

Alan,
I have the exact same machine and had to put it on a 30amp breaker.

[Alan Heffernan]

NEC Table 430.248 lists a 5 hp, single phase A/C motor at 28 amps.
Your nameplate rating will most likely be a little less.
If you go strictly by the national electrical code, the circuit would be required to be sized for 125% of 28 amps, or 35 amps.

You didn't say how far the run is (voltage drop considerations), but I'd run #8's and use a 40 amp circuit breaker. The code will allow you to use up to a 70 amp circuit breaker on this circuit.
- Jim
- Jim

Jim,
the run will be about 25 feet of wire
thanks
Alan

[Tom Veatch]

NEC Table 430.248 lists a 5 hp, single phase A/C motor at 28 amps.
Your nameplate rating will most likely be a little less.
If you go strictly by the national electrical code, the circuit would be required to be sized for 125% of 28 amps, or 35 amps...

Assumes that we are talking about a "motor circuit" in accordance with NEC 430. That means a dedicated motor load which operates continuously for periods of 3 or more hours.

I don't believe the provisions of 430 are strictly applicable here in light of the continuous operation criteria. I might add that neither does the code enforcement authority for my local area. My dedicated (hardwired) circuit for a 5HP cyclone is a 30 amp 10ga circuit installed by licensed electricians and approved by the local electrical inspectors. It doesn't meet the continuous operation critera of NEC 430.

[Jim Mims]

Assumes that we are talking about a "motor circuit" in accordance with NEC 430. That means a dedicated motor load which operates continuously for periods of 3 or more hours.
I don't believe the provisions of 430 are strictly applicable here in light of the continuous operation criteria. I might add that neither does the code enforcement authority for my local area. My dedicated (hardwired) circuit for a 5HP cyclone is a 30 amp 10ga circuit installed by licensed electricians and approved by the local electrical inspectors. It doesn't meet the continuous operation critera of NEC 430.

I agree completely, and on a run of only 25', 10 ga. wire on a 30 amp circuit breaker will work fine.
And your point is well taken about 'continuous' loads. How many of us run our equipment continuously for hours?
While you could use 10 ga. on a 30 amp breaker and it will work fine, given the opportunity to run a new circuit and for piece of mind, I'd still pull #8's.
Note that if you do experience occasional tripping, you are permitted to install a circuit breaker with a higher rating.
- Jim

[Jim Mims]

Gosh, it sounded like I was waffling in that last post. I was also thinking about continuous duty ratings when looking that up over the weekend and I need to take another look.
But when someone asks for a determination and you don't know their use, what do you do? While a planer isn't the best example, what about someone asking about a 5 hp table saw? And then you find out it's a cabinet shop where the saw may run for hours, even continuously except for lunch from time to time? And then they add a power feeder in the circuit.
"When in doubt build it stout"
For 90% of us, we'll use our equipment for a few minutes and move on to another operation. And as such, 12 ga. for a 3 hp motor on a 20 amp breaker and 10 ga. for a 5 hp on a 30 amp breaker works.
Then you have those guys in an older service area that have less than adequate power in the first place and have tripping problems. Or you find out their equipment is a good distance from the breaker panel.

I'd still run #8's. <g>
- Jim