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250V plug wiring question

J

Jay

Jan 1, 1970
0
I have a line cord with black, white and green conductors. I wish to
use it to connect to a 250V plug. Except for the green ground, does it
matter which of the other two are connected to which terminal? The
screws do not have the bronze and chrome colored screws. Both are
bronze colored.
Thanks,
Jay
 
D

Doug Miller

Jan 1, 1970
0
I have a line cord with black, white and green conductors. I wish to
use it to connect to a 250V plug. Except for the green ground, does it
matter which of the other two are connected to which terminal?
No.

screws do not have the bronze and chrome colored screws. Both are
bronze colored.

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.
 
J

Jay

Jan 1, 1970
0
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
 
D

DJ Delorie

Jan 1, 1970
0
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.
 
D

Doug Miller

Jan 1, 1970
0
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.

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.
 
D

DJ Delorie

Jan 1, 1970
0
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.

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.
 
D

Doug Miller

Jan 1, 1970
0
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.

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

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

Don Bowey

Jan 1, 1970
0
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.

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
 
D

Doug Miller

Jan 1, 1970
0
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.

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.
 
D

DJ Delorie

Jan 1, 1970
0
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

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.
 
R

Rich Grise

Jan 1, 1970
0
I have a line cord with black, white and green conductors. I wish to
use it to connect to a 250V plug. Except for the green ground, does it
matter which of the other two are connected to which terminal? The
screws do not have the bronze and chrome colored screws. Both are
bronze colored.
Thanks,
Jay

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

Cheers!
Rich
 
D

Doug Miller

Jan 1, 1970
0
No, it doesn't. Re-read the original post.

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

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

Doug Miller

Jan 1, 1970
0
Don't do it. Get a proper 250V plug and socket.

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

DJ Delorie

Jan 1, 1970
0
Yes, it does. I wrote that in response to your description of an
existing outlet. Re-read the thread including the context you
snipped.

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.
 
M

Michael A. Terrell

Jan 1, 1970
0
DJ said:
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.


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


--
Service to my country? Been there, Done that, and I've got my DD214 to
prove it.
Member of DAV #85.

Michael A. Terrell
Central Florida
 
J

Jamie

Jan 1, 1970
0
Jay said:
I have a line cord with black, white and green conductors. I wish to
use it to connect to a 250V plug. Except for the green ground, does it
matter which of the other two are connected to which terminal? The
screws do not have the bronze and chrome colored screws. Both are
bronze colored.
Thanks,
Jay
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.
 
R

Rich Grise

Jan 1, 1970
0
Huh? He already *has* a 250V plug. The cord he's asking about connecting to it
is perfectly fine for that purpose.

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

Thanks,
Rich
 
D

Don Bowey

Jan 1, 1970
0
Someone posted this in response to that.

I posted the following:

You posted:
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.


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?
 
D

Doug Miller

Jan 1, 1970
0
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.

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?
 
C

Charlie Siegrist

Jan 1, 1970
0
Circa Mon, 04 Jun 2007 18:31:53 GMT recorded as
Proper color-coding of the wires would not make that any less dangerous.

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.
 
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