Compressor electrical and autodrain question

I just bought this used compressor, which seems to be in a nice shape and runs okay, as far as I could tell.

I am going to connect it to this subpanel:

The compressor is rated 16 amps at 220 volts and has a pump release for startup. That means that it has EASY starts and NOT HARD starts.

I have 3 questions.

1. Can I connect it to electricity with a regular 20A 220V plug, and use regular flexible 10-12 gauge wire?

1. I have some nice AC switches/breakers, from a big UPS, 40 amp rated, can I install one on the compressor to serve as a power switch? This compressor does not have a power switch, and I would hate it to turn itself on in the middle of the night, or during the day to startle someone who might be in the garage. At the same time, I feel that pulling the plug is not a good solution.

2. Is there some smart autodrain device that I could install in place of the drain plug?

Thanks!

i

Looks like the subpanel is already full, unless nothing is connected to those breakers.

That's the way mine is wired. It's a 20A breaker and outlet with 12 gauge wire.

Seems logical but I'm not sure what would happen if you switch it off while it's running because then the pressure switch might not relieve the load and that wouldn't be good when you switch it back on. Hopefully someone that knows more about it will chime in. :-)

Harbor Freight sells two of them but they look the same to me:

?itemnumber=42221 Your tank is large enough that it may not drain enough so you might still need to open the drain manually from time to time. Also, when I installed mine the tubing provided kept blowing a hole in it because it was getting soft when it got hot. I complained and they refunded my money but let me keep the unit so I replaced it with a different type of tubing and it's been fine for the last 3 or 4 years.

Best Regards, Keith Marshall snipped-for-privacy@progressivelogic.com

"I'm not grown up enough to be so old!"

For draining I put in a street elbow, suff'ly long nipple, and ball valve, then a barb for clear tubing. Manually drain into a pail once a day. Clean, neat. An auto valve sounds like just one more thing that can malfunction.

I meant that I would connect the compressor to electricity by plugging it into a 220V outlet connected to the subpanel. (pictured on the link that I provided)

i

Why not hardwire it and use a switch duty circuit breaker to shut the power off? You can buy a larger subpanel for very little money if you need more circuits, as long as you don't overload the feeder.

Put those two 20A/240V outlets at the panel on the same breaker, and use the other 20A 2-pole breaker for your compressor. Either hardwire it, or install another outlet right by the compressor and plug it in with a short cord. Use the breaker for a switch -- just switch it off when the compressor motor is not running. When you switch it on, the motor will start up, but that's OK because the compressor has an unloader valve and the motor will not have to start under much of a load.

Bob

Would you consider changing your nickname? It is a little, um, unsuited for a guy who now owns such a formidable air compressor :-)

Whether you plug it in or whether you hardwire it using flex conduit will be decided by how soon you plan to move, and if you think you'll be sharing that circuit with another machine. If, for example, you may want to have 2 different machines plugged in when you weren't using shop air, you might well want to have it on a plug. If you wanted, you *could* knock out a hole in one of your outlet boxes and hardwire it in there, splicing in a 3-wire pigtail so both the outlet and the air compressor would be connected, and just use one or the other. It isn't up to code, but when you move you'll take your air compressor and just pop in one of those 3/4" knockout plugs and then presto it'll be back up to code. A one-man shop can run on the assumption of one machine at a time in my opinion.

Hardwiring it in flex conduit is cheaper than buying 12-SO3 cable and a 220 plug, as you'll soon find out.

Grant

1. Yes

1. Yes

2. Yes. Harbor freight makes one, but I would not recommend it. I had two fail in six months so I bought this one. (the link drops the = sign for some reason, Grainger item #4TK04)
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   just remove the drain valve, and screw it on! No extraplumbing like the HF valve.Greg

:)

I could as well hard wire it into the panel.

I think that cost is not a big deal, those 220V plugs and 12 gauge cords are not *that* expensive. What I want to find is an inline two pole switch.

You know, I want to do it nicely, the difference should not be huge.

i

Wouldn't he use SJO instead of SO? The J makes a big difference! I once made the mistake of ordering (unseen) some 12 gauge STO flexible cord to make a heavy-duty extension cord. The cord was so big I had to whittle down the jacket to get the ends to fit. Sort of fit.

Bob

switch?

You might want to check if the "switches/breakers" are rated for switch duty. IIRC, not all breakers can be used to reguarly switch the load on and off; it may compromise their ability to protect the circuit. They're meant for a more limited number of cycles than a switch would undergo.

You might want to add another box on the end of that gang of two 240V outlets and move one outlet into it, then use the box in the middle to house a "real" switch in line with the outlet. One posibility is the Cutler-Hammer B230AN, which is rated 5 hp at 240V single phase. That's in the neighborhood of the 16A you stated.

Pages 38-32 and 38-33 of

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Not sure what you mean by "inline" here, wou mean one that goes in the flexible power cord like a heftier version of a table lamp switch, or just something that goes "in the line" between the breaker and the outlet? Anyway, that C-H B230AN I mentioned in another post fits the latter bill. It's 2 pole for 240V motors.

%mod%

Thanks, good stuff. I am looking at it. The outlets are already protected by proper electcrical circuit breakers. So, if I add a switch in sequence to the breaker, I am not concerned about inability of that switch to protect the circuit. It is the job of the breaker.

i

Yes. A beefier version of a lamp switch. Remember, with a 220V plug, the circuit will be protected by a circuit breaker.

Yes, it looks quite applicable to my situation. Thank you.

i

There are motor rated toggle switches (just like the light switch in your wall to control your ceiling lights). They are more costly to buy, but they will handle the start stop load of your compressor quite easily. Just put one btween your breaker and you motor.

Most unloaders only unload at the top of the pressure cycle, if thats not reached or its between then your still starting under a heavy load.

If the unloader is a part of the pressure switch then this will likely be a problem if your using the breaker for a shutoff.

If you're going to use SO cord you'll end up with the compressor close to the panel, or a long cord strung across the floor. Consider locating the compressor where it is most convenient for the compressor to be, usually in a corner or some other place out of the way. Run conduit from the panel to adjacent the compressor's location, ending in a 4x4 box. Put a 240v 2 pole switch (looks just like a regular wall switch but more expensive, as others have mentioned) in the junction box and wire in the flexible conduit shown supplied with the compressor in one of your pictures. Free up one of those 20 amp 2 pole breakers in the panel, either delete one of the receptacles shown or wire both to one breaker, connect with 12 awg down your new conduit to the local switch in the junction box.

A few sticks of conduit, 40 ft of wire, switch, cover, and box are inexpensive for the convenience of locating the compressor in an optimum spot and not dealing with cords laying underfoot or getting half pulled out of the receptacle. It'll be a much neater looking installation also. Remember, you've already bought the flex and it's connectors.

Paul