250V plug wiring question

No.

That's because it doesn't matter which wire goes where -- 240V circuits use two hots and a ground, but no neutral. The two hots are interchangeable.

Note that my response assumes you're in the US or Canada. If you're not, then you need to specify where you are, because the answer may be different.

--
Regards,
        Doug Miller (alphageek at milmac dot com)

It\'s time to throw all their damned tea in the harbor again.

Thank you. I'm in USA Jay

In the USA, both "hots" are equivalent. The transformers that feed your house are 240V center-tapped, with the CT connected to your neutral and the other two taps being your two hots. The neutral is bonded to earth ground at one point in your wiring, usually at the main circuit breaker panel.

However, to prevent confusion, you should take a red marker and mark the ends of the white conductor, so that other people looking at your wiring don't think you thought it was 120v wiring.

With 3+1 wiring, the hots use the black and red wires, neutral uses white, and bare/green is for ground. If you only have black and white, it's a good idea (sometimes it's code) to color the white wire red to indicate its actual purpose.

For cord-and-plug connections -- which I think is what the OP was talking about when he said he had a "line cord" that he wanted to connect to a 240V plug -- this is unnecessary. The differing plug configurations mean that there is no possibility of a 240V plug *ever* being used in a 120V receptacle, or vice versa.

--
Regards,
        Doug Miller (alphageek at milmac dot com)

It\'s time to throw all their damned tea in the harbor again.

I was thinking about the other end - which would be inside the wiring box of the device. If it's a universal motor, which can be wired for

120 or 240, it's best to know what the original wirer intended.

And if you do one end, you should do the other end.

My paranoia is based on seeing a 120v outlet (not mine) wired to black/white/ground wire, with the other end wired to a 240v ganged circuit breaker. Pvsst.

there

That can be inferred from the plug on the end of the cord.

Proper color-coding of the wires would not make that any less dangerous.

--
Regards,
        Doug Miller (alphageek at milmac dot com)

It\'s time to throw all their damned tea in the harbor again.

If the white wire is to be used as a hot lead, US code requires that it be taped with black tape to alert workers that it it hot. Certainly that makes it less dangerous.

Don

Excuse me? The situation under discussion is an already-existing 120V receptacle that is already incorrectly wired to the two hot leads of a 240V circuit.

Please explain how proper color-coding of the wires to this inherently hazardous receptacle makes it any less hazardous.

--
Regards,
        Doug Miller (alphageek at milmac dot com)

It\'s time to throw all their damned tea in the harbor again.

No, it doesn't. Re-read the original post.

The OP has a black/white/green wire, and wishes to use it to connect [I assume a 240v device] to a 240v plug. Nowhere was a 120v outlet mentioned.

Don't do it. Get a proper 250V plug and socket.

Cheers! Rich

Yes, it does. I wrote that in response to your description of an existing outlet. Re-read the thread including the context you snipped.

Yes, there was -- by you, in the post to which I wrote that response.

--
Regards,
        Doug Miller (alphageek at milmac dot com)

It\'s time to throw all their damned tea in the harbor again.

Huh? He already *has* a 250V plug. The cord he's asking about connecting to it is perfectly fine for that purpose.

--
Regards,
        Doug Miller (alphageek at milmac dot com)

It\'s time to throw all their damned tea in the harbor again.

Ok, that does. But I try not to go off on tangents, so forgive me for not losing track of the original intent of this thread.

The mis-wired outlet incident only fueled my paranoia, it wasn't intended to be an example specific to this thread. If it's going to confuse the issue, I hereby retract it, and you may safely ignore my anectodes thereof.

there

Use red 'phase tape' on the white wire at both ends.

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Assuming single phase systems?, it does not matter as long the line cord can handle the voltage and load. seeing that this is a plug you're referring to, it's assumed you are plugging it to a proper 250 volt receptacle and the device it's connected to requires

250 volts? remember, the plug is what is in your hands that you insert, the receptacle is what's on the wall with the female insertion prongs.

If you're trying to branch off a couple of new circuits to get 120 from a 240 outlet, don't do that. the proper way is to use a sub box with de-rated breakers from that circuit and not from the receptacle, also this kind of system is not allowed where the possible use of life saving equipment maybe depending on the circuit because if for some reason the main breakers for the 240 tripped out, it would also trip out the 120 volt sub. The code for that is very questionable to say the least.

I have a heavy line from the main panel going over to the work bench that is #6-4 (red,black, white and ground), this gives me a 240 source and i have a sub panel/breakers that gives me the 120 I need. The main breakers for this line are 50 amps, the subs are 15 each. I also have all of this in EMT pipe because it's low enough to be reached by hands and code states it has to be covered some how. I guess they don't think romix jacket is sufficient any more other than used inside an enclosure of some kind.

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Oh, sorry. Then use the red tape as others have suggested (or red paint, magic marker, etc), assuming green is earth ground.

Thanks, Rich

On 6/4/07 12:36 PM, in article BQZ8i.32054$ snipped-for-privacy@newssvr12.news.prodigy.net, The OP posted the following:

Someone posted this in response to that.

I posted the following:

You posted:

No, you aren't excused, but thanks for asking.

Seeing two black conductors, or one red and one black still says both are hot. If one is white a person might unknowingly think it is a neutral. That is what the code prevents.

Got it now?

Code doesn't prevent people from doing stupid things with electricity, as should be obvious from DJ Delorie's description of a 120V receptacle that was wired onto the two hot legs of a 240V circuit. I was responding to your contention that this situation would somehow be made less hazardous by the use of proper color-coding on the wires. Code obviously did not prevent some fool from having wired the receptacle that way; there is no particular reason to suppose that proper color-coding would have done any better. Given that the outlet ALREADY EXISTS in that condition, it is not made any more, or less, hazardous by altering the colors of the wires that feed it.

Got it now?

--
Regards,
        Doug Miller (alphageek at milmac dot com)

It\'s time to throw all their damned tea in the harbor again.

Circa Mon, 04 Jun 2007 18:31:53 GMT recorded as looks like snipped-for-privacy@milmac.com (Doug Miller) sounds like:

Certainly it would. It would inform anyone with a proper understanding of electrical wiring that the wires she or he was working with were not meant to be used with a 120VAC receptacle. In the situation as described, the receptacle was properly wired, according to the color code of the wires at the receptacle end.