Wiring a 3 way light switch can be a difficult process particularly for diyers who are attempting the process with little to no electrical knowledge. One of the wires in the two three way switches is always hot assuming the circuit breaker is on.

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Can a 3 way switch go bad. Start by turning off the power to the switch circuit at the circuit breaker. Be sure the wires are not touching anything and the bare copper ends are sticking out of the boxes and not touching anything. Sometimes a 3 way circuit doesnt work because someone tried to replace a defective switch and did not properly connect the wires. Toggle each switch until the light come on. When i first investigated the switches on my own i assumed that this was normal for a 3 way switch in the same way that there is no neutral wire on a dimmer switch. A wall switch is a mechanical device with moving parts that gets thousands of uses over the course of its lifespan so its no surprise that switches eventually wear out and go bad.
Modern dimmer switches can save energy and light bulbs but they are damaged more easily than the auto transformers and rheostats that had been used to dim lights before spiras invention. Follow these steps to find which switch is bad. The first sign of trouble is when the switch begins to behave in a fashion that is abnormal in any way. Dimmer switches have come a long way since 1961 when joel spira invented the first electronic dimmer switch. Sometimes one of the switches has become defective. How to troubleshoot a faulty wall switch.
Locate a bad 3 way switch. Usually when a 3 way switch fails lights can be toggled on and off at one switch but not the other. Disconnect all the wires from both switches. The electric wiring could have a short the breaker may have tripped or the light switch may be bad. Occasionally changing a light bulb may not be enough to restore illumination. It turns out that none of the neutral wires were hooked up to the switches or the receptacles for that matter.
The steps i am going to describe may not be the most time efficient way to troubleshoot a 3 way circuit. If one of the two 3 way switches toggles the lights on and off the other 3 way switch has probably failed. If the breaker is okay then the light switch is the next likely suspect. One of the most common problems that homeowners face when tackling this project themselves is improper wiring which happens when the circuit wires are connected to the wrong screw terminals. The moving parts of a standard light switch are enclosed inside plastic casing so when the switch goes bad your only option is to replace it. The following method will address both problems at once.