Air compressor plug....

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ctaylo360860

ctaylo360860

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Im installing an outlet for an air compressor. My Square d slip stick says 60a breaker on #10 wire.... do I need to install a 50amp 250v single phase receptacle or will I need to install a 30amp 250v single phase receptacle.... I think it makes more sense to install a 30 amp because that’s all the conductors are sized for, and if i installed a 50amp receptacle there potential someone down the road someone will try and plug something that pulls more than thirty amps because The breaker is upsized for inrush....what’s your guys thoughts any and all help is appreciated?!
 
I see a problem in that a 50 amp 240v plug (5-50R) is only 3HP rated and 430.109 requires cord & plug disconnecting be HP rated equal to the motor.
(Is it possible you could post a picture of the nameplate.. 22A for a 5HP does not match NEC Tables)
 
augie47 said:
I see a problem in that a 50 amp 240v plug (5-50R) is only 3HP rated and 430.109 requires cord & plug disconnecting be HP rated equal to the motor.
(Is it possible you could post a picture of the nameplate.. 22A for a 5HP does not match NEC Tables)
Click to expand...
 
odd, but doesn't help with an answer. I don't know of a cost effective way to cord and plug connect it IF you want to meet Code due to the fact that the receptacle you picture is 3HP rated .
Perhaps someone else has an idea.
 
Conductors are sized 1.25% of load at 27.5 Amps... I guess I could set a disconnect with adequate hp rating, and amperage, and wire chord on air compressor into load side
 
augie47 said:
odd, but doesn't help with an answer. I don't know of a cost effective way to cord and plug connect it IF you want to meet Code due to the fact that the receptacle you picture is 3HP rated .
Perhaps someone else has an idea.
Click to expand...
Yeah. Im not aving much luck looking online for 5 hp rated plug and receptacle... day I did find one do you think it should be rated at 30amps or 50amps? Talked to Eaton they gave me part number for 480v pin and sleeve... ah430p9w ah430rp94 but I didn’t see rating for hp
 
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That is a "Special" air compressor duty motor. It does not follow the rules on NEMA horsepower. You can buy them at Northern Hydraulics as an example.

I've put them on 30 amp plug/receptacles an no one ever questioned it.

I also have always used a 30 amp breaker and #10 wire. No issues. (y)
 
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Frank DuVal said:
That is a "Special" air compressor duty motor. It does not follow the rules on NEMA horsepower. You can buy them at Northern Hydraulics as an example.

I've put them on 30 amp plug/receptacles an no one ever questioned it.

I also have always used a 30 amp breaker and #10 wire. No issues. (y)
Click to expand...
That’s how it’s wired now but has 50amp breaker, #6 wire, 50a receptacles and chord. I was going to put it on either a 50 or 60 amp breaker, depending what I find. Run #10 because motor conductors are sized 1.25 percent of nameplate rating. 22x1.25 equals 27.5 and put it on a 30a plug and receptacles so no one goes and plugs something 50amps that’s pulls way more than the conductors can handle....
 
ctaylo360860 said:
That’s how it’s wired now but has 50amp breaker, #6 wire, 50a receptacles and chord. I was going to put it on either a 50 or 60 amp breaker, depending what I find. Run #10 because motor conductors are sized 1.25 percent of nameplate rating. 22x1.25 equals 27.5 and put it on a 30a plug and receptacles so no one goes and plugs something 50amps that’s pulls way more than the conductors can handle....
Click to expand...

ctaylo360860 said:
Run #10 because motor conductors are sized 1.25 percent of nameplate rating. 22x1.25 equals 27.5 and put it on a 30a plug and receptacles so no one goes and plugs something 50amps that’s pulls way more than the conductors can handle....
Click to expand...

FWIW nothing in the NEC says you can't install a single 6-50R (250V 50 amp receptacle on a 30 amp circuit that has #10 branch circuit wiring. It's true!:)

Problem is though the Leviton 6-50 Industrial Grade Extra Heavy Duty is only rated at 3hp.

5374 - 50 Amp NEMA 6-50R Flush Mtg Receptacle in Black - Leviton

Black - 50 Amp, 250 Volt, NEMA 6-50R, 2P, 3W, Flush Mtg Receptacle, Straight Blade, Industrial Grade, Grounding, Side Wired, Steel Strap
www.leviton.com www.leviton.com
Click on technical information

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