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Old 11-16-2012, 03:45 AM   #1
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Why are some 240V circuits have 3 insulated wires and some have 2


Hi,

Please forgive this simple question but I would like to know why a stove has white black red for a 240 V application and a baseboard heater circuit just has black And white which are both hot...


Thanks

Peter

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Old 11-16-2012, 05:23 AM   #2
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Why are some 240V circuits have 3 insulated wires and some have 2


The 3 wire configurations are 240/120 volt and the 2 wire is straight 240 volt.

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Old 11-16-2012, 08:33 AM   #3
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Why are some 240V circuits have 3 insulated wires and some have 2


Because your base board has only a 240 heating element. Your stove has 240 heating elements + 120 volt clock, receptacles and light fixture.
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Old 11-16-2012, 03:12 PM   #4
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Why are some 240V circuits have 3 insulated wires and some have 2


So why is there no neutral wire? Don't normal electrical circuits have 1 hot one cold and one ground. Why does a baseboard heating circuit have two hots? Why does it not need the neutral?

Does the electricity combine at the baseboard heater to create the 240v? Or is it 240 down the black wire and neutral on white?

Peter
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Old 11-16-2012, 03:52 PM   #5
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Why are some 240V circuits have 3 insulated wires and some have 2


Stuff that uses 250/120 will have 4 wires (2 hots, N, G), stuff that is just 240 will have (2 hots, N or G, depending on the install for the use).
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Old 11-16-2012, 04:40 PM   #6
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Why are some 240V circuits have 3 insulated wires and some have 2


A purely 240V circuit consists of two wires, which I've labeled Hot+ and Hot-. These two wires will have the same voltage magnitude, but at any point in time they will be of the opposite sign: When Hot+ is +120V, Hot- will be -120V. So the difference between the two is 240V.

Many devices are designed to work when connected just to 240V.Water Heaters, some air conditioners, some motors, etc. The wiring for such a "pure" 240V device will consist of two insulated wires, (Hot+ and Hot-),plus ground. There is no need for a neutral conductor, because whatever current flows in to the device via Hot+ will flow out via Hot-.

However, many appliances (and other devices) need both 240V and 120V. The 120V part of the device is connected between one of the Hots and a third conductor, the neutral. The 240V current will come in via Hot+ and exit via Hot-; the 120V current will come in via Hot+ but exit via the Neutral conductor.

(We can't use the Ground conductor for the return 120V current, since the ground is to be used for safety purposes only.)
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