Single phase from 3 phase generator

Question

I got a good deal on a 3-phase generator, but everything I have is single phase. There's a sticker on it that says 230v 60hz.

The output is a 4-wire plug. I did some testing with my multimeter and it seemed I had the following:

• Green wire: Ground
• Red, Black, and White wires: Somewhere around 110v I believe (hard to read on the analog multimeter I had handy).

I'm used to having 110 house wiring have a hot wire, a neutral, and a ground, so I'm a little confused on what I'd have to do here. Would I wire one of the 110 wires to hot, the green to ground, and a common wire between all of my outlets as the neutral?

Second question is what to do if I wanted 220v? Two of the hot wires, green to ground, and common wire between all outlets?

And finally, I've read that it's best to distribute load across all the phases. So would that mean if I wanted 3 110v outlets, I'd want to wire one up to each of the hot wires?

Answer 1

Your 1st question, yes and common up earth and neutral, BUT are you qualified to do such work?

2nd question. If you measured the voltage between two hot wires you won't get 220 volts. You should see about 190 volts because line voltage is phase voltage (110 volts) x square root of 3 (1.732).

Question 3. I'm thinking about this one because potentially (possible apt word) appliances on one phase may cone into contact with appliances on a different phase and this would cause sparks if not properly insulated. Also, when you are old and infirm and you get an electrician round to fix or modify your AC distribution or ring mains he may be in for a big shock!

Answer 2

Are you sure it is three-phase. From the wire colours (and from your voltage readings, if I interpret them properly), it should be 120/240 volt, single phase.

You should measure about 120 volts between red and white, and between black and white, and about 240 volts between red and black, if it is 120/240 single phase. The white wire would be neutral, and would normally be connected to the green safety ground.

If it was three phase, delta, I'd expect 120 volts between red and black, and between red and white, and also between black and white, with no neutral.

Answer 3

I think Peter is right, if it was three phase you would have black red and blue, and it would be 208v. It is possible to have a high leg delta configuration (like on older buildings) where the high leg gives you 208v 1ph. You probably have 120/240v, and yes you want to balance your loads between the two phases (split the wattage between your 120v loads on red to white and black to white). This will balance the amperage on your breakers. But like they have said, an electrician should be wiring up these voltages.