Use dryer receptacle for 220 volt compressor?

I just bought a campbell hausfeld portable compressor vt-6271. Basically the biggest I could find in a portable. Rated at 15 amps at 230 volts it cannot be connected to a regular receptacle.

Now.. in my basement next to where I want to put compressor is an electric dryer. The dryer is plugged into an old 3 prong receptacle. The plug/receptacle are NEMA 10-30 r/p. This is an old 3 prong that has since been discontinued. Rated at 230 volts 30 amps.

Now, there are two similar prongs on the dyrer plug and one up top that is l-shaped. If I use a voltage tester, I get 220 volts across the two similar holes and 110 between the l-shaped and either of the two others.

Now, looking on the campbell-hausfeld site, I find some documentation that indicates I probably should have a NEMA 6-15 p/r or a 6-20 p/r. I think the 15 is 15 amp and 20 is 20 amp. Since this unit is rated at 15 amps, I suppose the 6-15 p/r is the probably correct.

Now the NEMA 10-30r is listed in NEMA as '3 pole, 3 wire' and the 6-15, 6-20 are listed as '2 pole, 3 wire'. I don't know what this means. I know very little about wiring. And I don't want to destroy my compressor the minute I plug it in. Also don't want to be shocked or start a fire.

What I want to know is.. can I plug the compressor into this socket?

The compressor is being shipped. So I don't know exactly what the wire/plug will look like but based on a lot of stuff I have read here I expect some wires without a plug.

Thanks for any info.

• Electricity explained

Here's my two cents:

It is possible to plug your three-wire air compressor cable into the three-wire dryer outlet. It is not legal to do so, but it is probably not dangerous either. If you do so, what you will have is the air compressor ground connected to the house neutral. In theory, both neutral and ground get tied back to ground at the service entrance. However, if the neutral ground connection is ever open (say someone is fooling around with the service), you will have voltage on the neutral. That's why the neutral is always insulated, while the ground is not.

Here's a couple of suggestions.

1. If you insist on doing this "on the cheap", add a second box near the dryer outlet. Install the recommended 20 amp grounding outlet in this box. Connect the two hot (black) wires in the dryer outlet to the hot contacts of your new outlet. Leave the neutral (white) wire alone. Now run a separate ground wire from the air compressor outlet ground to a known good ground, such as a copper water pipe. (I'm assuming the plumbing is properly bonded, not a safe assumption if there's any plastic pipe in the house.)

2. If you have space in your breaker panel for a double pole breaker, add in a new 20 amp breaker and wire a separate 230V circuit for the air compressor. This will be a "two-wire" circuit, meaning that you have two hot wires and a ground but no neutral. This is the right way to do it. If you're not certain how to wire it up, pay an electrician to do it for you. Running a separate circuit has the following advantages:

If done right, it's up to code.

You can run your dryer and compressor at the same time without blowing the breaker.

You can put the air compressor outlet wherever you like. You can even put a second outlet in your garage or wherever.

It's a code violation, it's dangerous electrically, it's a fire hazard, and even a blind house inspector/building code inspector will start writing as soon as they see such silliness.

It is possible and legal to use a dryer plug and receptical that has 4 terminals - 2 lines hot, a neutral, and a ground. This is often called a "mobile home" style dryer outlet. This can also be used to connect your compressor.
I suggest using a plug to fit the outlet, a short cord or wire set, and a connector that fits your compressor so you keep your compressor factory origional to preserve the warenty.
Having an electrician do the change is a good idea if you are not familiar with electical work.

I would listen to tlak unless I wanted a shock.

Some of these boys must have slept or had a hangover thru the Saturday morning wiring class at Home Depot. This neutral wiring mumbo jumbo could get a good man killed or seriously injured.

There are only 3 wires essential to a dryer or air compressor hookup and ground is definetly one of them.

If you are currently using the dryer plug, and the dryer is working at this time it is already connected to the breaker box correctly and is hooked to ground.

The short answer to the question about the air compressor is this.

Yes the air compressor will operate safely on the dryer wiring, as wiring is, without a bunch of wire swapping or circuit breaker rebuilds.

Let me try as your missing the important point of a neutral.

To have 120v you need one hot (blk) and one neutral (white). Both wires carry current. This is a circuit design.

As a safety, NEC added another wire called a ground (bare copper or green). This wire only carrys current "IF" something happens to the neutral. It's a safety and carrys current only when the neutral fails.

Yes both a neutral and ground go to a ground lug in the load center and appear to be both are grounds but they are not.

As Buickandeere pointed out one goes to earth ground (the copper rod) and is called the ground.

The neutral goes back to the pole transformer and is designed to carry current.

T_Bone

The whole neutral wire system does carry electricity, while the ground system never really should unless there is a problem; and since it is hooked to all exposed metal surfaces, you _do not_ want to start using a ground wire interchangably with a neutral wire.... You are then electrifying everything everyone touches.

This is the simple condensed version of a ground vs neutral wire system. There are more shades than just my black & white here, but....

--->Paul

Since then, I've learned to bend conduit and wired my 60x60 workshop/aircraft hangar, all to code, actually better than code. 9 120V circuts supplying 25 duplex receptcles, a 60A welder outlet, a 20A 240V outlet for a portable compressor/mig welder, and a 60A subpanel supplying a 7.5 horse compressor, and lights. LOTS of wire and conduit.

Talk with your electrician friend. Consider putting in a two breaker sub-panel at the dryer outlet. put the dryer outlet and the compressor outlet off of it. Take the ground plug for the compressor back to your main panel via a ground wire. Mount a placard, "turn one on, the other off, do not operate both devices at one time" This is your best, safest choice, you get circut protection sized to the devices you are running.

As someone has noted, your compressor uses two "hots" (the 240) and a earth ground. Your dryer uses the same two "hots" but has a netural instead, because it has a 120V motor in it and a light bulb inside probably. It also uses the netural as a earth ground, because back at your outside disconnect or the meter socket, the netural and the ground come together. The best thing you could do would be to drop a new wire to the basement, to run the subpanel I mentioned, you would use three wire with ground, a total of four wires and you would have the two "hots" and the earth ground and the netural and all would be happy.

Yes it will work, the netural of the dryer suffices as the earth ground for it, and if the compressor has a short to ground, the short would find its way to earth thru the netural cable, but its not proper, and I would only do this as a temporary, use it and unplug it when done method, using a patch cord made from a dryer cord and a 4x4 box and the outlet for the compressor, until you can drop the proper 3 w/grd cable.

All of the above is ASSUMING you have a modern, isolated netural/ground panel. If you have an older house where the netural and grounds are all mixed at the panel, well, just hook it up and drive on..... ....

Charles

I too like to figure things out for myself. That's why many years ago I bought the code book and learned it cover to cover.

OJT with 220V can result in all your problems being over.

I realize there are risks. Getting the right technical answer doesn't necessarily mean I will do it myself.

Basically I posted the question in an attempt to get a technical answer. Warnings are OK. But real answers are appreciated (and that's what I really wanted).

I think you are being argumentative, good bye loser!

I bark in your general direction....

w00f!

I guess reading electrical code books really soured you on life. I think you are the loser.