# Question about 240 voltage

## Main Question or Discussion Point

I have been trying to understand how 240 voltage works in devices such as motors or heating elements I know that current needs a complete path to flow to produce power and in the typical 120 volt circuit the common is what completes the path. In a 240 volt circuit nothing more than two 120 volt legs are needed to make the motor or heating element work. I understand that the two 120 volt legs are 180 degrees out of phase. Is it the push-pull action between the two out of phase 120 volt legs which allows current to flow through the device and produce power or work? Just curious and can't seem to find the answer anywhere. Thanks!

## Answers and Replies

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Averagesupernova
Science Advisor
Gold Member
Think of it as 2 batteries in series. The neutral is the connection between the 2 batteries. The 2 hot wires are the ends of the batteries. Of course, the battery example is DC where the 240 volt circuit is not. The neutral is a center tap on a transformer.

Hi Aveagesupernova. Thanks for your reply. I'm not sure I understand how the center tap becomes part of the circuit. Is this possible because of the 180 degree phase difference between L1 and L2 and the resulting potential difference as the current reverses making each line a neutral as well as the hot wire?

I have asked two electrical contractors this same question and both were unsure.

Thanks!

Averagesupernova
Science Advisor
Gold Member
Try to get your hands on a small step down transformer with a center tap. I think some hands on work could clear things up for you. Naturally, be careful when working with the primary side connections. I wouldn't say each wire is both a hot and a neutral. That is definitely incorrect. As one leg goes positive with respect to neutral (center tap) the other is going negative. So this means the the voltage between the ends (2 hot wires) is always double the voltage between the neutral and hots. Same thing as the battery example I gave earlier.