Residential Voltages

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la_engineer

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My friend has a single phase panel in house that uses a 3c14 cable (separate phases) on two 15A 1 pole branch circuit breakers using the white as a neutral for both circuits. One circuit serves a three way to the living room light and the other circuit serves a separate room. The problem is that the living room three way switch has 120V on one side (black) leaving the switch and the other side (red) leaving the switch has 60V (give or take a few volts). This condition exists even with the cables removed from the swith (all except the incoming).

Need help in determining where the 60V is coming from.

la-engineer
 
I spent a day chasing this ghost. Turn the switch off, put a lamp in the light, measure the voltage on the pigtails. I believe you are recording back EMF from things like the transformer on your furnace, flourescent lights, etc. As soon as you add any path to the source your voltage will go to zero. If you were to measure the current in this scenario it would be in the mA range.

I learned this the hard way. Pulled new MC cable once, changed 2 old switches, and had receptacles and lights apart all over the place.

Regards,
 
What problem are you trying to correct? If the only symptom is this "phantom voltage" then there is no problem. If you found this voltage while trying to diagnose some electrical problem, then perhaps we can help.
 
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