Can you use a compass to detect the currents in wires in the walls near light switches in your home?

Answer 1

Yes, the needle would point perpendicular to the wire, and parallels to the magnetic lines of the wire.

Another answer The above answer would be correct IF you were dealing with a DC circuit AND there was a load on the circuit, but house wiring uses Alternating Current, and the compass needle would attempt to reverse directions at the rate of 60 cycles per second. Effectively, the needle would simply act strange when it's near house wiring, IF there is a current load on the wire.

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To add to that, use a proper cable-locator, not a compass.

Answer 2

No, the magnetic field brought about by current flow would not be detected by a compass. Any field that was present would be cancelled out by the approximation of the parallel conductor on the return leg of the circuit.

Answer 3

No, a compass cannot be used to detect currents in wires within walls. The magnetic field created by the current in household wiring is not strong enough to be detected by a compass. To detect currents in wires, specialized tools such as a non-contact voltage tester or a multimeter should be used.