I want to wire my 240v compressor in my garage and need a little advice.

I'm going to move the compressor when I build my new garage so I just want to do a quick and easy install right now. I have no free space left in my service box but my dryer(electric) is close to my compressor. If I install a box and a 20amp breaker next to the dryer outlet, can I tap off the dryer wiring(good for 60A) for power as long as I don't run both at the same time.

The dryer circut uses 3 wires red(120), black(120), white(neutral)and ground (not connected to anything), I think my compressor needs black(240) and white (neutral), and ground (bare). Do they ever use the white as a hot? That would obviously change the picture somewhat.


If not, then how do I get 240v in a single hot wire? Should I wire the red and black together at the breaker? Will that give me 240v with no problems?

Thax in advance

 

Aye Carumba,
Well first off this seems like it would be illegal somehow, but that out of the way. In residential systems 240 volts is combined by a red and black DO NOT put 2 wires together to combine for 240 volts it dosen't work that way. Now keep in mind, I'm not familiar with electrical codes in the US so this might be off, but yes, you could run a junction box off your dryer and it would work just fine. As you say, don't use the dryer at the same time. And I can gaurantee this wouldn't pass electrical approval.
They do use a white wire as a hot wire sometimes, but you still need a neutral. all AC power works on the principal of power In-thru-out.
And also make sure you ground it somehow. you don't want to risk frying your equipment, your house, or yourself.

Good luck.

 

I did exactly what you are describing at a rental house in the past and it was no problem. I simply came off the dryer circuit and if there was an overload (when the compressor kicked in and the dryer was on) it just tripped the breaker.

As I recall you never see 240 on the multimeter, you get there with two 120 circuits. I put one in an empty position in the box of another house and you straddle two busses with the breaker so you have two 120's.

I am not trained as an electrician, but I have managed several compressor installs without burning down the house or myself. I really want a compressor now, but have neither the room nor the budget.. but air tools are soo nice!

 

You guys are a big help...

So I have to keep the black and red 120v lines seperate all the way to the load (Compressor). The compressor has two plain lugs and a green ground lug. Does it not use a normal neutral? This is what is confusing me. If there is no white Neutral, then the bare ground wire becomes the neutral acording to the diagram on the compressor. Also, I am using a 240v, 20a socket and plug, they only use two wires and a green ground.

I'm much more familiar with Direct Currect than AC that's for sure, but I still think AC and DC have some similarities. AC moves from higher potential to lower potential, like DC and needs a good Neutral path (like DC ground). If I remember correctly (big if) the differant "phases" of the two 120v lines give you 240v at the load or something like that.

Above all, I respect 240v just like I respect GM C3I distributorless ignition coils (8amps @ 100,000 volts!)

 

[QUOTE]Originally posted by Roceye
[B]You guys are a big help...

 

ya I think I got it now...just like to be sure about things before
I start a project. I hate doing things twice!

 

I just bought a new compressor the other day. 6hp, 30 gal tank, 150 psi max, 8.6 scfm @ 40 psi. (single stage) what kind are you using?

 

I used to be a do-it-yourselfer; however, my hourly rate as a graphic designer eventually allowed me to hire professionals to do the things at which I was not entirely proficient. So, unless you are an electrician (it doesn't sound like you are), call an electrician for safety's sake. The house you don't burn down or the body you don't electrocute may be your own.

 

Mission accomplished.

The only hard part was getting power from the dryer circut without using any splices or wire nuts. I ended up running the dryer circut into the sub box first then just piggy backing the wiring for the dryer to the top lugs of the busses where I could get a good tight connection. then I attached a surface mount dryer socket to the sub box. All nice and neat, if not to code.



lucid,
Mine is a craftsmen twin cylinder, single stage, 6.5 hp, 60 gal, 9.9 scfm, 130 psi max pressure. Not the greatest compressor in the world but it was on sale a couple months ago. It should run all my second hand worn out air tools (all my nice ones are at my shop) just fine.

lvs2k,
"So, unless you are an electrician (it doesn't sound like you are), call an electrician for safety's sake."
Where's the fun in that? If I wanted to be safe I wouldn't be toolin' around in S2000....