Electrical question

[Oregonhunter5]

So what's this mean. A short?
Plugged my air compressor into a short, small gauge extension cord, used it tons before, and it started to flame up, and it melted the prong on the compresser plug.
What's this mean?

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[speeddemon94]

Too much draw through the cord.

It will work for a bit, but eventually it gets too hot and shorts, causing your fire.

Find out the draw required for your compressor and go get yourself a cord rated for more than that.

 

[Oregonhunter5]

Ok. I couldn't believe how that metal burned up. Kind of spooky.
So how do I understand what cord it needs? Just get a really low gauge. Overkill is better?

 

[Oregonhunter5]

Also. Is that cord toast now?

 

[speeddemon94]

Lol, yeah, cord is shot.

So get a good replacement plug for the compressor, or possibly a completely new cord. If it's like many compressors I've seen, the whole cord should be easy to replace.

As for the gauge question, yes, bigger is better.

 

[Skier]

the compressor probably has a label stating what the current draw (or power used, from which you could calculate current draw) or you could probably look up the specs only, then make sure both the cord and circuit you plug it into can handle the load. Might have also just been a bad cord, as I'm surprised it burned up before popping a breaker somewhere.

 

[Ramjet12]

The cord is toast....literally. It's a little trickier to get a motor cord the correct wire size. Motors have a running current and a start-up current. The start up current is very high but very brief. What's the horsepower rating of your air compressor? There should be a tag on the motor that shows you the current draw.

 

[rstews]

A 12 gauge extension cord is rated at 20 amps and a 14 gauge is rated at 15 amps. Should be a nameplate on your compressor motor for amp draw. If any doubt go with the 12 gauge. BTW a short means the current (amps) doesn't go through the load, in this case the motor, but goes directly between the hot and neutral. In that case there isn't anything to limit the current and you saw the result of that. I agree with speeddemon94, replace the cord.

 

[Oregonhunter5]

Thanks guys. It's a 120v 15 amp motor. The cord was 12 gauge. The motor is a 5hp. It's a 26 gallon upright cambell hausfield.

 

[Oregonhunter5]

Lol. When this happend, I tried 3 times plugging it back in. That wasn't smart. Sucker flamed up every time. Like a fireworks show.

 

[lowly monk]

You may need to replace the outlet now.

 

[jbett98]

Another thing to consider is how far away is the plug that you are using from the load center, what else is running on the same circuit at the same time.
And how many other outlets are wired between the two.
I made a special 20 amp outlet just for my compressor to run off of.
Try running the compressor without an extension cord and run a longer air hose.

 

[Skier]

Do you know your lime voltage is good? If you voltage is low, its possible it would still want a certain power draw and to get the same power out of a lower voltage, current would have to increase... For example, if your outlet is only supplying 90v instead of 120, then you 15a motor is going to draw 20a so it still uses the ~1800VA (~1280W) that it needs to run. Even a sag down to 105v is going to cause your current to be about 17a, so if your extension cord rated to 15A, then it might overheat, especially if its long and even more so if long and most of it is still wrapped up in stead of being spread out to full length.

 

[Mark W.]

WHY DIDN'T YOUR BREAKER POP????? Wow you could have a fire start and nothing to stop it. Time for some serious checking.

 

[WhyteCheddar]

OHM'S law is your friend.

Ohm's Law Calculator

 

[ZigZagZeke]

It sounds like you had a mechanical failure in the extension cord. Get a new 12 ga extension cord and inspect the outlet and make sure it wasn't damaged. Also try plugging your compressor into the outlet without an extension cord, just to make sure it's not the compressor itself.

 

[solv3nt]

Are you sure that the burned up cord was a 12ga? I know that there are a lot of 14, 16, and even 18ga cords out there, and I suggest never using them. 14ga is rated for a 15a breaker, but typically you only run lighting loads off of 14ga wire. 12ga wire is rated for 20a. If you have too much current draw through your cord, then the insulation melts, causing ground and the hot leg to short together. Depending on the severity of the short, the circuit breaker may or may not trip, in many cases with resistive heating elements, you may be pulling more than 15a for a period of time before it heats up enough to trip.

Motors do have a high inrush current, which typically isn't prolonged enough to trip a breaker, especially if it is rated at 15a. The wall out let is probably toast, and you will want to take a look at that.

 

[Mikej]

What happened with the plug going up in flames is, over time there was resistance where the male and female connect. Resistance causes heat, the tension that holds the male and female together was lessened due to heat, more resistance, more heat etc, FLAMES. The plug will always be where there is the most resistance in the run. Had you had a direct "Short" the breaker would have blown. Check the prongs, and look for signs of heat on the female side of the cords. If the prongs are discolored/dark, or there are signs of the plastic around them getting hot, don't use it. You also want a good firm felling when you plug something in.

I always feel the plug and wire for heat when using an extension cord also.

Mike

 

[Oregonhunter5]

It sounds like you had a mechanical failure in the extension cord. Get a new 12 ga extension cord and inspect the outlet and make sure it wasn't damaged. Also try plugging your compressor into the outlet without an extension cord, just to make sure it's not the compressor itself.

Ok. How do I rule out the compressor?

 

[Glock23gp]

If you have a fairly new house, plug it directly into an outlet in your kitchen or bathroom with NO extension cord. Both locations have been required to be 20amp circuits for a long time per the National Electrical Code and the State of Oregon.

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