Reuse 240V Dryer Circuit?

[rayb]

I have a question about 240 volt dryer circuits. I apologize if this is a duplicate topic as I just found the site and forums and was unable to find any matches.

I have an unused 240V dryer circuit in my garage (we got a gas dryer and it only required 120V). I would like to save some time, money and sweat to add some power to my garage using this circuit. It is currently made up of 3 wires, look like 10AWG copper, pulled through buried conduit from a double-pole? (2 toggles tied together) 30 AMP breaker in my main panel.

My main question is, what would be the best way to use the existine wires to power an air compressor that requires a 240V Single-phase receptacle?

Secondly, is there a safe, legal way to use the same wiring to

[6pack]

To get started, I would repost if garage is attached to house or seperate from house. Entire different set of code rules for either or. Not sure if underground wiring was only way to get to attached garage or seperate run to unattached garage.While at it if seperate garage tell us if also general wiring out there for lights and general outlets? Also post the amperage draw of compressor mentioned.Also size of conduit and type(thinwall, ridgid, IMC.) Need this info to help in your answer, numerous solutions may be available to you. GL

[rayb]

Oops. I think I may have found my answer. I ran across the 220 subpanel for compressor post by bchase and realized this would probably work for me as well. I would like to confirm though, if I upgrade the breaker at the main panel to a 50 AMP and then install a subpanel in the garage (around 75-100 feet away) with a 220 breaker for the compressor circuit and a 110 for the lights and some outlets, I would be allright.

If I run the subpanel this way, what about the neutral return from the 110 circuit? Would it just tie to the subpanel's neutal buss? Would it be right for the neutral and ground to be tied together at the subpanel? I want to be lazy but I also want to be safe.

Thanks again...Ray

[rayb]

I'll do the best I can. Wiring was here when I bought the house. the garage is attached and the plugs and light in the garage are all wired from the house.

I presume it was run after construction as it is run from the service panel through a hole in the stucco below the panel into the conduit and then underground. If I am understanding the conduit types correctly, it believe it is 1/2" ridgid conduit (thicker walled from the panel to the entry through the garage wall, then run in thinwall from there to the dryer plug.

I couldn't find the exact current load on the compressor but the manual did say that it could be wired to a 15 AMP circuit providing it was "dedicated" with no other loads on the line. I figured on a 20 AMP anyway just to be safe.

Originally Posted by wannabee

To get started, I would repost if garage is attached to house or seperate from house. Entire different set of code rules for either or. Not sure if underground wiring was only way to get to attached garage or seperate run to unattached garage.While at it if seperate garage tell us if also general wiring out there for lights and general outlets? Also post the amperage draw of compressor mentioned.Also size of conduit and type(thinwall, ridgid, IMC.) Need this info to help in your answer, numerous solutions may be available to you. GL

I can guess where you are going with the question of outlets and ligts already there. I had originally planned on just extending the existing circuit but it's already loaded pretty well. I extended the existing single light circuit to serve 4 flourescent shop lights and an outlet for a chest freezer and refrigerator. It also serves the lights to the master bedroom and bath next door and the lights dim when the freezer fires up, hence my desire to include another circuit for either lights or the appliances.

There's also an outlet that is currently running the washer and gas dryer. I could extend this for more plugs but adding the freezer and fridge to this one (along with the 4 plugs in the house on the same circuit) likely wouldn't gain me much.

Hope that's enough. I look forward to your help.
Ray

[imported_joed]

If the wire is # 10 you can not upgrade the breaker to 50 amp. You must leave it at 30 amp. If the cable only has 3 wires then you can't use it as a sub panel. You need a black, white, red and bare ground to make a sub panel.
You can change the receptacle to a 30 amp receptacle to match your compressor and use it. Your compressor will not require 110 so a 3 wire cable will work fine for that.

[rayb]

Originally Posted by joed

If the wire is # 10 you can not upgrade the breaker to 50 amp. You must leave it at 30 amp.

Is this because #10 wire cannot carry more than 30 amps? If so, what size wire and breaker would I need to effectively feed a 20 amp circuit for the compressor and another 15 amp 110 circuit for lights and plugs (assuming I pull a fourth wire to provide the proper grounding for a subpanel)?

Thanks again.

[6pack]

You said this is attached garage! You also said wire run in conduit? You also said appears to be ridgid. The ridgid pipe would be your ground. Depending on U/G pipe run(condition and # of bends) not sure if you can pull another pair of #12 in with that existing circuit,if so you would be set.Not sure how NEC looks at this when existing. Again if legal(pipe fill). Might even be able to install a six circuit panel fed by that #10 with 30A D/P protection. Lets see what WG has for you on this. Need to know exactly amp draw on that compressor. Hang in there till later.

[rayb]

[quote="wannabee"]Need to know exactly amp draw on that compressor. quote]

I'll look at the compressor again tonight and post the draw. I honestly appreciate all the help.

The pipe looks in good condition, appears to only have 4 bends (estimating 2 below ground). As to pulling more wire, I think I shouldn't have any problem getting another 2 #12 wires through. It would be tight with romex but the single, solid core (like is in there now) would fit fine.

Look forward to your input.

[Mark_R]

Ray,

Take a thorough look at
http://www.homewiringandmore.com/hom...rageshowp.html

provided by the good folks that run this site. There's a lot if information there to digest, so I'd suggest printing it out for review. If the link gets broken in the post, write it down and type in into your browser manually.

Also note that "tight with romex" (or single core wire) is not a good thing... there are valid engineering concepts (building codes) that prevent those 'pipes' from being stuffed with too many wires, for your and others safety....

[rayb]

Ok. I was able to find out the current draw on the compressor motor. It pulls 13.1 amps. I anxiously await your recommendations.

Ray