Can this air compressor be saved?

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aude
Posts: 211
Joined: Sat Feb 11, 2012 11:06 pm

Can this air compressor be saved?

Post by aude » Mon Jun 19, 2017 1:11 pm

I unwisely connected my air compressor to what turned out to be an undersized 100-foot extension cord in order to power an air tool in a remote corner of our yard. The connection was as follows:

normal 15-amp outlet (non-GFCI)
|
25-foot heavy-duty extension cord usually used with the compressor
|
100-foot medium-duty extension cord NOT usually used with the compressor
|
compressor

The compressor ran especially slowly, and I shut it off after about 30 seconds. The connection between the two extension cords, especially on the medium-duty cord, became hot and a bit melted and charred, then the circuit breaker blew. Since then, I used the compressor once, without the medium-duty cord. The connection between the heavy-duty cord and the compressor began smoking. I am trying to figure out whether the compressor is damaged, or whether it's just the heavy-duty cord (which appears fine). Any ideas on how to check this out?

Thanks

Teague
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Joined: Wed Nov 04, 2015 6:15 pm

Re: Can this air compressor be saved?

Post by Teague » Mon Jun 19, 2017 1:21 pm

Sure, grab a meter and check the resistance of the cord(s). Replace cord if need be. If still problems, check the resistance of the compressor motor across the hot and neutral, and across each of those to ground. Contact the manufacturer to see what those resistance readings should be, replace motor if needed and available.

Alternatively, or if the give the above seems foreign, give the compressor motor a sniff. If it clearly smells burnt you have released the magic smoke that makes all electrical devices operate properly.
Semper Augustus

Jack FFR1846
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Re: Can this air compressor be saved?

Post by Jack FFR1846 » Mon Jun 19, 2017 1:30 pm

Does it operate properly if you plug it into the wall directly with no extra cords? I've used my compressor to run with remote tools but since it weighs 300 pounds and is bolted to the floor, the way to do it is to run long air hoses.
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lthenderson
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Location: Iowa

Re: Can this air compressor be saved?

Post by lthenderson » Mon Jun 19, 2017 1:49 pm

I would first check the heavy duty extension cord for continuity and resistance with a multi-meter. There is probably damage to it from the first incident that isn't visible.

Here is an good example showing how that is done.

https://www.youtube.com/watch?v=gbqFr1SpITs

aude
Posts: 211
Joined: Sat Feb 11, 2012 11:06 pm

Re: Can this air compressor be saved?

Post by aude » Mon Jun 19, 2017 3:00 pm

Thanks for all of the great responses!

alshayed
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Joined: Fri Aug 19, 2016 1:34 pm

Re: Can this air compressor be saved?

Post by alshayed » Mon Jun 19, 2017 3:28 pm

Also keep in mind the cord or plug from the compressor might be damaged too. You can buy replacement cords too if so, probably have to pull it off the compressor to test it though. Just remember to write down how it was wired so you can put it back on properly!

aude
Posts: 211
Joined: Sat Feb 11, 2012 11:06 pm

Re: Can this air compressor be saved?

Post by aude » Tue Jun 20, 2017 12:05 am

Thank you all. The compressor's cord was damaged, probably because it was undersized for this (mis)application. The heavy-duty cord was OK. I rewired the compressor with a "new" cord made using the male end of the heavy-duty cord and about five feet of cord from that. Works fine, grounded and all. A Boglehead thrifty fix.

sjt
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Re: Can this air compressor be saved?

Post by sjt » Tue Jun 20, 2017 7:23 am

Aude,

Hopefully a real electrician / engineer can chime in here, but I believe what happens is a high amperage draw when you connect multiple cords together. You risk damaging the motor of the compressor also.

There will be a significant voltage drop to more cords connect together due to the resistance in the wire and the connection points. The motor will try to draw the same amount of power (P = IV) and since the Voltage is lower, the current (I) will need to increase, causing your cords to heat up / melt.

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