I need to replace the three prong plug on my air compressor. Before I head to Ace, can anyone tell me what size/rating plug I need? Here is a picture of the compressor.
Much appreciated!
Mike
It says 15 amp 120v, which is pretty much the default for US electrical cords. But look at the outlet you plug it into and make sure that it's a standard outlet and not something weird.
John T.
Thanks, John and J. Clarke!
It's a standard outlet, but the cord itself is really thick, so I thought I should be careful about what kind of replacement plug I use.
Mike
The cord should have some tiny writing on it to indicate the wire size. eg 12/3 Sometimes the extra thickness is just the higher grade of insulation - better toughness and flexibility in cold .. John T.
Presumably, you have the plug that needs to be replaced. Personally, I would be more concerned with the configuration of the plug (assuming that it appeared to be OEM and not somebody else's add-on) rather than the receptacle you'll be plugging it into. If you get the right plug, you'll be forced to insert it into the correct receptacle.
Heavier cord than you'd expect? No worries. You can save breaking out in a cold sweat until such time as you see a compressor connected to the receptacle with a 20' length of lamp cord. ;)
Electricity explained
I think its time for me to explain about 240 current and why it is so different from 120 volt service. First of all, it's twice as big. Secondly, it'll shock you more. Outside of that, 240 is really two 120 volt lines coming to your house from different parts of the globe. The up and down 120 comes from the northern hemisphere, and the down and up version comes from below the equator.
Without trying to get technical, it all boils down to the direction water flows when it goes down the drain. In the top of the earth, it goes clockwise, while on the bottom of the earth it goes counter clockwise. Since most electricity is made from hydro dams, the clockwise flow gives you an up and down sine wave, while the counterclockwise version gives you a down and up sine wave. Between the two, you have 240 volts, while either individual side only gives you 120 volts.
This is particularly important to know when buying power tools -- which side of the globe did they come from? If you get an Australian saw, for instance, it will turn backwards if connected to a US generated 120 volt source. Sure, you can buy backwards blades for it, but that is an unnecessary burden. Other appliances, like toasters cannot be converted from Australian electricity to American electricity. I knew one person who bought an Australian toaster by mistake and it froze the slices of bread she put in it.
If you wire your shop with 240 and accidentally get two US-generated 120 volt lines run in by accident, you can get 240 by using a trick I learned from an old electrician. Just put each source into its own fuse box and then turn one of the boxes upside down. That'll invert one of the two up and down sine waves to down and up, giving you 240. DO NOT just turn the box sideways, since that'll give you 165 volts and you'll be limited to just using Canadian tools with it.
It says 15 amp but also says 2 hp. Normally, 2 hp motor would require
12 gauge wire, 20 amp plug and receptacle.
Go to ACE and get one of their plastic molded plugs. (Here is a picture from HF)
Cut your current cord, strip the wires back a bit and assemble.
15A * 120V = 1800W 1HP = 746W ~ 2HP < 1500W Seems do-able on a 14ga cord (easily) and 15A plug.
My show vac says 5.5HP and it has a 16ga. cord and NEMA 5-15 plug. I bet that keeps you up at night. ;-)
Yeah but it's a Sears Crapsman and we know they tend to embellish (lie!)
Seems like it but it is not. Start up amps is a lot higher, and I've yet to see a recommendation for 2hp shop motor run on 14 ga wire, or 15 amp fuse. Even fractional hp motors like washers, dryers, refrigerators and so on should be run on 12 gauge, 20 amp circuits.
Doesn't keep me up a bit. I would love to see that 5.5hp motor drive a
24" planer, or his air compressor for that matter. Actually, I think a 2hp motor would normally require 10 ga wire, not 12.A 5.5 hp motor would seldom be 120, but 220 or 3 phase. A 5.5 hp motor would draw a lot of amps at startup, and running under load would not last long on 16ga wiring, if at all. Your shop vac HP rating is, as you well know, using methods that are meaningless when comparing motors and work output.
My shop runs on 12 ga wire, and the only big motor is a 3hp and that runs on 12 ga, 240 volt circuit.
That's why I said "Normally". Even so, I would not run the motor on a
14 ga, 15 amp circuit. You could get away for awhile with a 15amp plug and receptacle and switch perhaps, but I wouldn't recommend it, even if the motor was only 1/2 hp.
The biggest grief I encounter when buying a replacement plug is getting the correct part for the cord diameter. Some plugs have nice, secure cord clamps, but only work on a limited range of acceptable code diameters. Some plugs use a collet style cord clamp, but I find these to be rather poor for any cord that gets much plugging action, although some of the yellow colored can-shaped plugs with the three-fingered collet style retainer are actually quite good.
-BR
Since we're making rocket surgery out of a simple plug replacement, I'll throw in another option.
Get an extension cord with the same gauge wire as the current compressor cord. Cut off the female end and wire it into the compressor.
No, he should buy a new compressor. ;~)
No ! .. buy a new compressor and take the cord from that new compressor - install it on the old compressor - then - - this is the important part -
- re-box the new compressor - perfectly - take it back for a refund .. say that it was received as a gift and never opened.
Always wiling to help.
No, it's perfectly within the code. It would be better on a 20A circuit (most NEMA 15-5Rs are on 20A circuits) but there is no need for the cord to be 12A. It's overkill (though I'd probably do it).
The compressor isn't likely to actually require 2HP for long periods, either.
Yikes! You didn't run 8GA wire! You slacker!
Ordinary 110V plug for your part of the world. Standard household outlets in the USA are 110V 15 amp. Some are 115V 20amp indicated by a cross cut on one pin, but the same plug will go into either outlet.
I doubt that compressor will draw 15 amps unless there is something wrong with it.
5 amp fuse mine untill I switched the wiring on the motor over to 240. Now it's on a 20 amp 240 volt circuit - no more worries.
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