I have two black wires running to a light switch that I need to extend about a foot. I cannot identify the hot wire because both wires are black and I have no white wire. Can I cap off both wires and then test each with a voltmeter? If the circuit is not complete, will the hot wire still be live?
If you plug an extension cord into a grounded outlet, you can use the VOM to read between the ground on the other end of the cord the wires to find the hot one (assuming that the grounded outlet is really grounded - check that first). Or if you're near a water line, you can take readings between the wires the waterline (preferably cold).
Both wires in a switch are in the hot leg. There is no neutral. One is the hot feed, the other goes to the hot wire of the device. If you have a neutral or a ground in the box, you can test for hot with a meter. Touch one probe to one black wire, the other to neutral or ground. If you get ~120V, that;s your hot. Otherwise, the other wire is. If all else fails, you can use a pen tester, but the meter is much more accurate. Hope this helps.
yes you can cap both and yes the hot wire is still hot. take volt/muilt meter set to a/c 200volts touch red lead to one black wire black lead to other . if it +115-125 red lead is on hot wire if it reads -115-125 the black is on the hot wire
ok, a light switch is different then a outlet plug. the black wire is the hot wire and comes in to one side if the switch and goes out the other side. the switch just open the circuit to turn off the light or closes the circuit to turn it on.
