I recently was given a 6hp 25 gal Porter-Cable Air Compressor (CPF6025VP) that kicks out my 20 amp breaker at around 80psi and will not restart with even 20 psi in the tank.

I measured the amp draw on it and initial start was very high then leveled out around 7 amps and kept rising above 15 until the breaker tripped at around 80 psi. Amp rating for the motor is 15A (GE motor model is 5kcr49tn2403x). I read through other posts and was planning on replacing both run and start capacitors but I'm having trouble finding the right ones.

I cannot find original replacements and the ones with matching ratings have different terminals on them and I cannot find them that come with a wiring diagram. My run capacitor has 2 red and a brown and start has two black. run capacitor model M40FY33 -40uF -370VAC 50/60Hz start capacitor 52A103967-1 -400-480MFD -165VAC -50/60Hz

Anyone that could point me in the right direction of some capacitors and how they should be wired would be greatly appreciated

Please Let me know if any other info would be helpful. Thank in advance!


p.s. -unloader and check valve are working

-motor spins free

  • Welcome to StackExchange! This is not a shop-for-me site and we don't do product recos, but I would get the exact same capacitor and wire it in exactly the same way as OE. My secret place to find weird motor stuff like caps is Galco, otherwise electronic suppliers like Mouser, Digi-Key or Grainger. Aug 27, 2018 at 22:15
  • 1
    Did it work ok prior to you getting it? Did they give it to you because it wasn't working? Are you using an extension cord?
    – mikes
    Aug 27, 2018 at 22:19
  • Is the motor tripping the breaker in the panel, or its internal thermal protector? Aug 27, 2018 at 22:46
  • Also, how are you measuring the amp rating of the motor, and how long does it take the breaker to trip from startup, if it's the panel breaker? For that matter, if it's tripping the breaker in the panel, what make/model is said breaker? Aug 27, 2018 at 22:48
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    Tripping the breaker in the panel, qo square d single pole 20a breaker. Was given to me by guy who was moving and didn't have room but he knew it wasn't working properly, said you have to drain all air to get it to refill. Amperage was measured on load line entering the switch with clamp meter. The amperage rating I used to decide breaker size was labeled on motor stating 15a. Also plugged straight into outlet.
    – Jireland90
    Aug 28, 2018 at 11:04

1 Answer 1


At 15A, that is a 3HP motor (assuming 240V single phase here), the "6HP" is a marketing term that means WHEN the motor is slowed down by a change in the load to it's "Break Down Torque" speed, it will develop 220% of rated torque, VERY briefly, in attempting to get the motor back to speed, so 220% torque at a just slightly lower speed results in 200% HP for that brief moment, and they are allowed to present it that way (which I think is a shame). the operative issue however is that during that moment, which for a compressor will be when the pressure is highest, that motor can actually be pulling 33A, not 15A. Most likely your meter is averaging and/or too slow (not enough samples) to be giving you the correct current at the moment the breaker is tripping, but of course, the thermal element on the breaker is seeing and reacting to it. That would also explain why you can't reset it when the pressure drops, because at that point it has nothing to do with pressure any more, it's a thermal cool-down time frame and thoise are specifically designed around the time it will take the rest of the equipment to cool down too.

Changing the caps will not fix this. You need a bigger circuit. a 20A breaker can only be used at 16A continuously (80%). Upgrade to a 30A breaker and #10 wire.

  • 1
    It is a 120V motor btw... Aug 27, 2018 at 22:46
  • Yes, 120v states 6 hp but I was using the 15a rating on motor to decide breaker size.
    – Jireland90
    Aug 28, 2018 at 11:06
  • If it's 120V and says 15A FLA on the nameplate, then it's a 1HP motor. I don't see how even the "marketing HP" trick gets it to 6HP... Nevertheless, the situation is the same.
    – JRaef
    Aug 28, 2018 at 21:07
  • I also forgot to mention before that on restart the motor will struggle for a second or two then the breaker pops. Only reason I think it may be a problem in the motor. I will give a bigger breaker a try though and get back. Thanks for the input!
    – Jireland90
    Aug 31, 2018 at 15:04

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