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#### AidaCarrell

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Why is the white wire for hot water tanks not connected to common but connected directly to what appears to be a double pole breaker?

#### Bondo

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##### Master General ReEngineer
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Ayuh,.... Because it's 240V, 'n not 120V,....

#### Plumbvoltage

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Most hot water heaters are straight 240V. So usually 2 cond w/ground nm-b is used.

#### AidaCarrell

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I would like to have a deeper understanding of how the current is flowing. In this case, is ground wire action as neutral?

#### Mingledtrash

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I would like to have a deeper understanding of how the current is flowing. In this case, is ground wire action as neutral?
here ya go.
That's it, no neutral. Now, if you are paying attention, then you are probably wondering "If there isn't a neutral wire then how is the circuit completed?" The answer is that when one hot wire is negative, then the other is positive, so the two hot wires complete the circuit together because they are "out of phase". This is why 240 volt circuits connect to double pole breakers that are essentially two single pole breakers tied together. In the main panel, every other breaker is out of phase with the adjoining breakers. So, in essence 240 volt wiring is powered by 2 - 120 volt hot wires that are 180 degrees out of phase.
http://www.nojolt.com/Understanding_240_volt_circuits.shtml

I am not an electrician but i think he may be wrong on the 180 degrees. but that is the layman example.

#### AidaCarrell

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Let me restate this to make sure I understand. The difference in sine wave amplitude between ground and hot is 120V. The difference in sine wave amplitude between two out of phase hots is 240V. Is this correct?

#### joed

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Let me restate this to make sure I understand. The difference in sine wave amplitude between ground and hot is 120V. The difference in sine wave amplitude between two out of phase hots is 240V. Is this correct?
Correct, sort of.

The measured voltage is 120/240. The actual sine wave peak to peak amplitude is more like 170/340 volts.

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