I have several benchtop workshop machines that I bought and used whilst in Asia - they are UK or International single phase 220v (or 240v if UK). The service cords are typically hot + neutral + ground (various colors depending on what market they were sold in).

I currently have a 3kW step-up transformer that works fine. Plugs into a normal 110v 15A outlet and my machines plug into the transformer. The difference in frequency 50Hz vs 60 Hz does not seem to have any noticeable effect on the performance of the machines. I only use one machine at a time and so the output of the transformer has proven to be quite adequate. But it would be convenient if I had another power outlet in addition to the transformer.

I have been "fixing up" the garage in my recently acquired 60 year old home and came across a loose cable that just had black PVC tape wound over the end. I was careful and checked it with a multi-meter. One black, one red, no neutral or ground. 220v across the two conductors. Quite heavy cable, maybe 10g conductors. I suspect that it was originally for a water heater.

I have terminated this cable at a Leviton 5821 6-20R 20A-250v receptacle and have run a 12g ground from another adjacent receptacle.

My question is - can I somehow connect my International 220v single phase machines to this USA 220v receptacle? If so, how should I wire them? Maybe I need some kind of intermediate "dog bone" or similar?

 

For one thing US is 240V, not 220V. My voltage normally runs about 248V.

 

No electrician but you can't bootleg that ground that way, I'm pretty sure. I'm not even sure you can connect to a US 240V ckt legally w/o having that transformer.

Have to wait for an electrician to weigh in.

 

In the US, household electricity is usually supplied with 240V split phase. Transformer output from the pole (or pad) is 240V with center tap grounded (neutral). Thus you get 120V from each half of the circuit.

In many cases, 220V European and Asian equipment will work fine at 240V without neutral. However, some are not able to handle 20V higher voltages.
I once had a hi-fi amplifier made for 220V and I wired it to 240V. It worked fine for a while, but eventually parts of the logic circuit got fried because it was using a simple transformer to create low voltage power for the logic circuit and the output ended up higher than normal voltage because it wasn't regulated.

Most portable step up transformers out there are actually just a transformer with 1:2 winding, which will output 240V with 120V input in the US. If you been using this type of transformer and your equipment hasn't failed yet, then directly wiring it to 240V will work fine as well.

If you actually have 120V to 220V transformer, you are better if using it because it will be the voltage your equipment is expecting.


As for the hot - neutral vs hot - hot issue, unless your equipment is grounded through neutral, you will work fine as safe.
Since European plug with 2 round pegs are non-polarized anyway, they won't be grounded through neutral and double insulated in most cases.



What size breaker or fuse is on this circuit? Protect it with 20A since you have 20A outlet.



It is now allowed in NEC 2014 as long as it is from the same breaker panel, but chanced are it isn't adapted yet in most areas.

 

So many good responses.

Sorry. I stated that I measured 220v across the black:red. It was closer to 240v. As some have stated.

So. Do I simply wire the plug hot=black, neutral=red, ground=ground?

 

Not mentioned yet is the effect of frequency on the motors. They will run slightly faster if 50hz motors. How that affects longevity seems to be a gray area.

 

It doesn't have to be black to black and red to white, but yes of the two U.S. hots you have available one goes to the tool hot and one goes to the tool neutral. If you're talking about basic woodworking / shop tools it should be no problem at all to use these on the circuit you have. As ray mentioned the speed may be slightly higher but will likely make no practical difference in the function of the tool.

 

Excellent. Thanks for all of the really helpful responses. Much appreciated.