3 Tips for Troubleshooting Three Way Switch Wiring

After completing three-way switch wiring, it sometimes happens that the connection fails. You may have turned the circuit back on and made sure the bulb was new, but for whatever reason there is a break in the circuit.

If this is the case, you will have to do some troubleshooting of the wiring in order to determine where the problem lies. A three-way switch involves two switches and a light or some other receptacle. It is a more complicated wiring job with more room for error. With some tenacity, though, you will determine the cause of the problem and get the circuit to work.

The first thing you should do is check to make sure you turned on the right circuit breaker. Believe it or not, a non-working circuit may only be due to a lack of power at the source. If the circuit breaker was turned on, it is important that you turn it back off before troubleshooting connections. The problem will likely be wires connected wrong, bad terminal screw or pigtail connections or a faulty switch.

Tip 1: Check the Wiring

Starting at the light box, check for proper wiring between pigtails and on the terminals. Make sure the wires are where they should be. From the source, a white wire should connect to the silver or neutral terminal on the light.

The black wire connected to the brass or hot light terminal should lead out of the box to the first switch. The hot wire from the source should connect with a pigtail to a white wire marked black with electrical tape. The two grounds should be pigtailed with a third length attached to a ground screw on the box (unless the box is plastic).

Move to the switch boxes and check the same thing. The white wire marked black from the light box should carry the current from the source to the bottom brass screw on the first switch. Make sure the top brass screw has a red wire attached to it which leads to the top brass screw on the second switch.

A second white wire marked black should lead from the silver screw on the second switch to the silver screw on the first switch. Lastly, a black wire should lead from the bottom brass screw on the second switch to a pigtail in the first switch box and onto the hot terminal of the light.

Tip 2: Check Connections

Another possible cause is either faulty pigtail connections or improper connections on the screws of each switch. At each screw, the wire should be looped and fed over the thread in the direction the screw will turn to tighten. Wires should be twisted together before the pigtail is screwed on.

Tip 3: Check the Switches

Lastly, you can check the workability of the switches themselves. With the power turned off, remove the connections from a switch. Twist the two hot wires together and fasten a wire nut onto them. Turn the power back on. If the other switch works to turn the light on, then the first switch is bad.

Whether it’s wrongly connected wires, the connections themselves or faulty switches, troubleshooting a three-way switch connection will unveil the culprit so you can solve the problem.