220v to 120v

[angelodp]

Guys, I need to run some shop machines that are 120v in a space where there is 220V avail and inadequate 120v. Is there a transformer box that can be plugged into the 220v socket and put out 120v. I need to run a typical
Radial arm saw with a vacuum system and the shop lights.

A

[paulster]

Yup. You need a step-down transformer designed for running US equipment in Europe since these are 220/240 -> 120V.

For example, see the Step Down and Autotransformers section on the Hammond site:
http://www.hammondmfg.com/5cline.htm

[Phil_S]

These allow you to convert power in either direction. The 100W model is only about $20, all the way up to the 2000W model at over $150. I'd imagine the 100W model is more than adequate for one machine.
http://www.parts-express.com/wizards/se ... N=39553780

Overall, my guess is that using a good quality converter is probably the most practical and cost effective solution.

[Structo]

I thought the American 220vac line was simply two 110 lines, so if you just take one hot and the neutral you should get your 110-120vac, I think it would be half the current supply as the full 220vac.

Simple way to test is to measure the voltage between a hot and neutral.

[M Fowler]

This statement confused me

inadequate 120v

How good can the 220v be if a simple 120v receptacle isn't available.

If your not able to do the work yourself get an electrician and run reliable 120v power to the area needed.

Mark

[Phil_S]

I thought the American 220vac line was simply two 110 lines, so if you just take one hot and the neutral you should get your 110-120vac, I think it would be half the current supply as the full 220vac.

Simple way to test is to measure the voltage between a hot and neutral.

I believe some USA 220V supplies don't have a neutral. If there is a neutral, you can do it, if not, you can't. If I understand this correctly, the 220 supply should consist of two 110v feeds and one neutral. There also needs to be the "green ground" wire present (often bare wire) if you want to wire a typical 3-prong 110/120v receptacle. I'm going to guess for the equipment described, a fully serviceable 3-prong is virtually required.

Given the potential downside of doing it wrong, I'd either opt for the power converter, or call an electrician.

I've run electric wire before, and, like many of us, don't have the ordinary fear of electricity. It is one thing if you are pulling a supply from the breaker box, allowing for the typical 3-wire 110/120V supply that's used today. It is another to rewire old work (existing 220 in this case), particularly where there is any sense of doubt whatsoever. Fire and death are real dangers when this sort of thing is done wrong, making that call to the licensed electrician comparatively cheap. Since the OP (Hi, Angelo) expresses some initial reservation about the situation, I suggest the prudent path is to err on the side of caution. IMO, this is not a DIY situation.

[Structo]

Yeah it probably wouldn't be up to code, especially in California, to re-wire the 220.

Ange your best bet if you have room on your existing circuit breaker box is to run a new circuit to your shop with it's own breaker, like a 30A.
I would run 10 gauge.

[angelodp]

Hi guys, I have access to an older out house once used a sculptors studio, near me ( next door ). The owner had her husband put in a 220v line for her compressor. I see three lines coming into the building, so 2 hots and a neutral seems certain. There is also a line somewhere under the building that has a 120v run with a 15 amp fuse ( I guess ) as when I use that line with the florescent lights, vacuum and RAS the lights dim....ergh!!. My neighbor was an electrical engineer so i'm sure he did a good job on the 220v.

I don't want to disturb the setting as she may want to continue her sculpting at some point, so the step down box seems a good solution. I will have to calculate the total needs to get the right wattage unit, right. Whats a ball park figure for shop gear? !00w to 200w for one machine at a time?
One step closer to a luthiers den and making those acoustics....ahhh!

Thanks guys
Ange

[martin manning]

Ange, if you have a 220 outlet (240, really?) I believe you can put in a duplex 120V recepticle and split the 240 line into two 120's. You'd need a separate earth ground, which may be there already. Might be a good plan to consult an electrician to make sure you are not doing something that violates code.

[angelodp]

The RAS is 10amps 110v - or 1100watts and the Vac is 11amps also on 110v for 1200 watts. So does that mean i will require a unit that is rated at
2500 watts?

Looking into that duplex idea, maybe the easiest way to go.

[Aurora]

if you have a 220 outlet (240, really?) I believe you can put in a duplex 120V recepticle and split the 240 line into two 120's. -------Might be a good plan to consult an electrician to make sure you are not doing something that violates code.

Only if that 220V outlet has BOTH neutral and ground.. - makes that 220V outlet a "4-holer".. otherwise - NOT -I'm afraid......

[angelodp]

Has two hot legs and a neutral. What about this gadget?

http://www.pnw4x4s.com/forum/index.php?topic=3701.0

[martin manning]

Yes, that's basically what I was talking about doing. I think that would work for you and require no mods to the existing wiring.

Aurora, you edited out my comment about a separate ground being required: "I believe you can put in a duplex 120V recepticle and split the 240 line into two 120's. You'd need a separate earth ground, which may be there already."

[Phil_S]

Ange,
See what Aurora said above, and what I said. You can build that gizmo, but your ground hole in the receptacle won't be grounded. You only have a three wire feed to the 220. That makes it two hots and a neutral. You are missing the ground. If your appliances have three prong plugs, you want the ground plug to really be grounded.

Another idea -- consult a licensed electrician on this one -- is to see if you can use GFCI outlets in the home brew converter box. As I understand it, these can be wired without the ground, but I'm not comfortable saying how it works, whether it works, or whether it's appropriate for what you want to do. BTW, a pair of those GFCI receptacles will probably cost around $25.

[paulster]

If you have two hots and a neutral available then a 4-pin 240V outlet will allow you to use 120V or 240V off the outlet depending on which connections you make in the plug.

It would be very easy to make a 4-pin 240V plug to 3-pin 120V socket adaptor lead which uses one hot, the neutral and ground, but you'd want to consult an electrician on whether this causes any code issues. I'd imagine it would be okay since the point of the 4-pin plug is to allow dryers, etc. to use 240V for the heater and 120V for the control circuitry and motor, so it's designed with the expectation that the neutral will be current-carrying.

Since you're looking at about 2.5kW you'll be wanting a big transformer, especially as you need overhead for the power factor since these will be inductive loads.