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Joined: Sep 2002
Posts: 14
I
INTP Offline OP
Member
My craftsman 5.5HP air compressor keeps tripping the breaker when it cycles on. not every time, but 1 out of 3 or so. If it doesn't trip when it kicks on, it will be ok until the beginning of the next cycle.

It's on a 20A 115V circuit by itself. The 12GA run to the sub panel is only about 20' of wire. I've tried a different breaker, and it does the same thing. It's a tandem (two breakers on one 115V pole), but it did it with a regular breaker, too. The subpanel is Square D homeline. Nothing else gives me any problems, either at the subpanel or the main. I've even run my MIG welder off the same receptacle (not at the same time) and it didn't trip it.

Any suggestions?

Joined: Nov 2002
Posts: 267
W
Member
Check the nameplate for fla (full load amps) You may have to run a larger line and a larger circuit breaker. 5.5hp is 4103 watts at over 30 amps. Not sure if that motor actually uses that, so check the name plate and size accordingly. Hope this helps.

Joined: Dec 2000
Posts: 4,294
Member
Probably time to call an electrician!

[This message has been edited by electure (edited 12-06-2002).]

Joined: Sep 2002
Posts: 14
I
INTP Offline OP
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Thanks, wirenut. I can't find the FLA anywhere. It just says 115V/60Hz/1PH/15A. Max developed HP=6. Lots of stuff about flow (cfm).

The voltage at the receptacle is 123.5, FWIW.

Joined: Oct 2000
Posts: 4,116
Likes: 4
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You should call the Manufacturer and see if they are aware of any issues with this unit.

Bill


Bill
Joined: Jul 2002
Posts: 175
E
Member
With a 15 amp rating, this motor will draw a starting inrush current of 45 to 75 amps. It is not surprising that the 20 amp breaker trips. This motor is permitted a breaker rated at 250% of 15 amps.

2.5 X 15 = 37.5 amps. Try a 30 amp breaker.

Ed

[This message has been edited by electric-ed (edited 12-06-2002).]

Joined: Nov 2000
Posts: 2,148
R
Member
Does this problem occur when the storage tank is empty? If it only occurs when there is pressure in the tank, it sounds like the "unloading" valve is not functioning correctly. This valve dumps the air from the compressor cylinders when the motor stops turning and makes the starting load much less. If the motor tries to start with pressure in the cylinders, I would expect it to trip the breaker.
Don


Don(resqcapt19)
Joined: Dec 2001
Posts: 440
Likes: 3
Member
If this compressor is "cord and plug" connected with an "OEM" cord, then it was designed to be "plugged in" to a receptacle. Maybe the bearings in the motor are about to fail, or the internal parts in the compressor are worn, and causing the motor to be overloaded. Are there any other loads on that circuit?

Decompressing,
Doc


The Watt Doctor
Altura Cogen
Channelview, TX
Joined: Oct 2002
Posts: 70
B
Member
Is it a breaker or a GFI that's tripping. If it's a breaker then see electric ed above. If it's a GFI then plug it in on a non-GFI receptacle.

Bob

Joined: Aug 2002
Posts: 33
M
Member
I used to have a Craftsman 5.5 HP compressor. The book says to put on dedicated 15A circut or a 20A circut. I ran it on a 15A circut and never once tripped the breaker.

The motor has a plastic box over it...so you cannont read the nameplate without taking off the cover.

(Removed long non-working url)

[This message has been edited by Webmaster (edited 12-07-2002).]

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