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Old 02-16-2009, 07:41 PM   #1
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240 wire question


I have seen 240 4-wire outlets that have a red/black/white/ground and I have also seen outlets that have a red/black/ground but no white (neutral).
First question, if there is no neutral where does the current go? Second, if you have have an appliance that has a red/black/white/ground setup but you are connecting to an outlet that has red/black/ground what do you do?
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Old 02-16-2009, 08:14 PM   #2
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240 wire question


well, I can answer your first question. It goes back the other hot wire. There would be 120 volts between each hot wire and the neutral. As for the second, I'm guessing you will need to rewire as something in your appliance needs 115 volts?
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Old 02-16-2009, 08:22 PM   #3
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240 wire question


4 wire feed would supply a device that requires 120 volts. You need the neutral for that. Dryers and stoves would be examples.
3 wire feed would be for a device that only requires 240 volts. Welders and compressors would be examples of those.
You would have to pull new cable to go from a 3 wire device to a 4 wire device.
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Old 02-16-2009, 08:23 PM   #4
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240 wire question


You will need to run a new 4 wire cable with the correct receptacle.
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Old 02-16-2009, 08:23 PM   #5
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240 wire question


A 240v "4-wire" circuit is really a 120/240v circuit as it also has 120v loads. An example would be an electric dryer. These appliances have line-to-line loads as well as line-to-neutral loads.

A straight 240v appliance has no 120v loads so there is no neutral required. These are "line to line" loads only.

Connecting a 120/240v appliance to a straight 240v circuit is dangerous since the bare ground will be carrying the 120v neutral current.

Older "3-wire" dryer circuits were 120/240v circuits with no dedicated ground. The neutral served as the ground as well.
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Old 02-16-2009, 08:29 PM   #6
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240 wire question


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4 wire feed would supply a device that requires 120 volts. You need the neutral for that. Dryers and stoves would be examples.
But these dryers and stoves are on 240 outlets why do you say they are 120 volts?
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Old 02-16-2009, 08:33 PM   #7
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240 wire question


Usually in ranges and dryers, the only thing that is 240 volts is the heating elements.
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Old 02-16-2009, 08:35 PM   #8
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Usually in ranges and dryers, the only thing that is 240 volts is the heating elements.

I think I see you are saying they are 120/240 in that they have 120 and 240 elements in the appliance, correct?
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Old 02-16-2009, 08:41 PM   #9
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240 wire question


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I think I see you are saying they are 120/240 in that they have 120 and 240 elements in the appliance, correct?
The elements are 240, things like clocks and electronic timers are normally 120.
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Old 02-16-2009, 08:44 PM   #10
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I think I see you are saying they are 120/240 in that they have 120 and 240 elements in the appliance, correct?
No. they are 120/240 appliances. Usually the heating elements are 240 line to line loads and then there are smaller 120 line to neutral loads like timers and electronics and such.
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Old 02-16-2009, 08:46 PM   #11
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The elements are 240, things like clocks and electronic timers are normally 120.
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Old 02-16-2009, 08:53 PM   #12
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240 wire question


For example; from my range's instruction booklet, which has a four wire cable (including neutral white) the requirements are as follows:

"A three-wire or four-wire single phase 120/240 volt 60Hz
AC only electrical supply (or three-wire or four-wire 120/206
volt if specified on nameplate) is required on a separate
circuit fused on both sides of the line (time-delay fuse or
circuit breaker is recommended). Do NOT fuse neutral. The
fuse size must not exceed the circuit rating of the appliance
specified on the nameplate."

How can you use a three wire electrical supply when the range itself has a four wire connection?
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Old 02-16-2009, 08:56 PM   #13
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How can you use a three wire electrical supply when the range itself has a four wire connection?
The ground and neutral would be tied together.
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Old 02-16-2009, 08:57 PM   #14
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240 wire question


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The ground and neutral would be tied together.

And that is a legitimate connection?
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Old 02-16-2009, 09:00 PM   #15
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And that is a legitimate connection?
Most dryers come with a chassis ground jumper hooked to the neutral connection that you remove if it is a four wire hookup.
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