I will be using 12/3 Romex to make two separate circuits. As you know, 12/3 is 20 amp wire, for two separate circuits. There is a red wire (hot) for one circuit. There is a black wire (hot) for another circuit. There is a white wire (neutral) for both circuits. In other words, the black wire and the red wire both share the common white wire. Let’s say that one circuit draws 15 amps (red wire) and the second circuit draws another 15 amps (black wire). That is 30 amps. However, they both share the common white wire. The white wire is now carrying substantially in excess of 20 amps. In this case, it is carrying 30 amps and at full load from both circuits, it would have to carry 40 amps. Add it up. It means that the white wire is carrying the voltage from both individual 20 amp circuits (40 amps). The white wire would melt and catch fire instantly. Hence, 12/3 circuits and 12/3 Romex seem dangerous --- but they are used all the time. I don’t understand.
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2006-06-24
17:10:11
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5 answers
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asked by
Radial Wave
1
in
Maintenance & Repairs