- Ground wires always go to ground
- To see if a circuit is correct, there must be a loop. Follow the black wire from the panel (source) and then through the light or outlet and then along the white wire and back to the panel. If there’s a loop, then it’s correct.
Testing a Circuit
When testing a circuit, you may find that using a non-contact voltage tester beeps when you don’t expect it to. For example, in the diagram below, if the switch is off, you’d expect the black wire to have zero voltage and not beep, but the non-contact voltage tester beeps when you place it on or near the black wire. This can be confusing. To verify whether the circuit is working properly, use a 110/220V voltage tester with probes.
- Touch the probes to the black and white wires, as shown in the diagram below.
- Turn the switch on. The tester should illuminate.
- Turn the switch off. The tester should not illuminate.
- If you get these results, your circuit and wiring are correct.
