How to change 240v 3ph plug to 240v single ph plug

Lucky Dave fired this volley in news:aa814$544446aa$43de0cc0$ snipped-for-privacy@news.flashnewsgroups.com:

While all the small home shops are dying to get 3-phase, instead of using converters and VFDs, you have it.

If you have 3-phase, then you already have single-phase.

If it's delta, pick any two power pins (NOT ground!), and get 240 single- phase. If its Wye, pick any two power pins (NOT ground!), and get 208 single-phase.

You don't get 240V single phase from Wye service without a boost transformer (cheap).

You need to know which service you have, but it's easy to determine with a resistive load (like a 240V incandescent bulb, or two 120V bulbs of the same wattage in series) and a voltmeter. Just apply the load across any two power pins, and check the voltage.

If it's 240, you have delta service, if 208, you have Wye service.

LLoyd

LLoyd

LLoyd

Hire an industrial electrician. The way you worded your question makes me think that it would be the safest course of action.

Does your machine need to have a neutral lead to run 120VAC subsystems (like coolant pumps or lamps), or is it a pure 240VAC load?

If it is a pure 240 VAC load, then pick any two of the three phase leads and you will have 240 VAC between them. (Of course, be sure to have the safety ground connected, too.) If your three phase is open-delta then two of the phases are real, and the third phase is virtual, so be sure to pick one of those two phases. Usually, I think, you will find that one end of the two real phases is grounded, but if there is also a setup to give you 120 VAC as well, then not so.

If you need a true 120 VAC neutral, you probably have problems, unless you have a step-down transformer to run the 120 VAC loads.

For three phase, you could have either of two different connectors, BTW. One (with only safety ground and no three-phase neutral) will typically have four pins arranged in a circle (for twist-lock connectors). But if there is a three phase neutral *and* a safety ground, there are connectors which have the four pins in a circle and a single round pin in the center. In that case, the round pin will be the ground, and one of the four will be the neutral.

First -- get a connector to plug into the existing outlet which you have, and open it up. One of the screws should be painted green (this is the ground, and should get a green wire from the machine you are connecting. Then two of the wires from the machine should be black and red. (White, if present, is usually neutral, but is sometimes used as a phase when there is no neutral) Usually, you will find letters stamped near where the wires go in in the plug. "X", "Y", and "Z". Probably you should use the "X" and "Y" as your 240 VAC. But *always* remember that you need a green from the green screw on the connector to the frame of your machine. tool.

Or -- you *could* hire an electrician to run a 240 VAC feed from your breaker box to where you want your new machine to plug in. If you feel uncomfortable working with this, an electrician is good piece of mind.

Good Luck, Don.

DoN. Nichols formulated on Monday :

There are Tooo many IFs in the US power system for someone who has to ask to be told enough to save his life.

The only answer is GET AN ELECTRICIAN :/

In the 240volt world it is generally a no/no to do anything of that nature without a license ( I would do it but I have survived 80 years and been fixing things electric for about 65 of those.) :-?

Dontcha get 208 or 262v out of that, depending on wiring style? (delta v. wye)

Larry Jaques has brought this to us :

I rest my case. There are so many possibilities in the US.

In Aus the domestic supply is nominally 230/400 volts wherever but many old installations are still at 240/415 which is not much of a problem. Any suburban house will have 4 wire three phase 230/400 at the street, Only those wanting it, Air Con etc will have all three phases connected, but thats the way it is anywhere. Of course there are industires with higher voltages and special conditions.

Electrically it's pretty simple, but if you're calling a receptacle (what's on the wall) a plug (what's on the cord), you probably should get an electrician, particularly if this is a commercial shop where you have liability issues if you fry an employee.

Gunner Asch fired this volley in news: snipped-for-privacy@4ax.com:

I doubt he knows. L

Right, get an electrician to at least look over the job that you did and ca ll the device/appliance manufacturer to make sure (though they've usually a llowed for more or less than nameplate voltage input).

Here in the US the NEC (National Electric Code) says to describe voltage at 120V, 208V, 240V, 277v. But manufacturers sometimes round up or down to th eir specs. Additionally you have peak and off and other factors that result in getting more or less than the 120v or the 240v that you think you are g etting. (involving non-North American systems)