information on wiring in a three way light switch?

Question

have three red wires two blue, two white, and one black new switch different lay out and does not work when wires are placed in same as old switch

Answer 1

I'm an electrician and my advice is the obvious one. If you can't do it, don't. I've lost count of the amount of jobs i've been to to fix DIY jobs that not only don't work, but are dangerous.

Answer 2

I just checked and found the instructions in the UK are completely different than in the US. The colors are different and so is the terminology. My answer is for the US, not the UK way.

A three way switch takes three wires, as was stated. Actually, three plus a ground. Two are travelers, as stated. They simply go from one switch to the other. They do not attach to the power from the breaker, nor to the light. That part was also correct on the other post. Most people use regular 14-2 plus ground for this cable. They place red tape on the white wire to indicate that it is a hot wire, not a neutral.

The odd colored lead on one switch comes from the breaker box. It is the hot lead and it is probably a black colored #14 wire. The odd colored lead on the other switch goes to the hot lead of the light. As stated, the two travelers go to the two leads on the switch that look the same. The two are interchangeable, don't worry about which of them is which.

Those two travelers go to the same two leads on the other switch. Again, it does not matter which one is which. Just do NOT connect either traveler to the odd lead on the switch.

The white wire, probably #14 is the neutral. It comes from the neutral bus in the breaker box and goes to the neutral side of the light. It is not connected to the switch at any point.

Caution: in some wiring layouts, the white is used as a common between the switches. When this happens, the white can be hot, i.e. energized with 115volts. Be careful about that. It should be maked with red tape, but sometimes it isn't. Other wiring layouts use 14-3 plus ground. It depends partly on where the existing wires are in the building.

The ground is attached to the metal box that holds one switch, on to the metal box that holds the other switch, and finally on to the box that holds the light fixture. It is either green or bare #14. Some countries use the term "earth" instead of the term "ground." Same thing, different name.

Answer 3

You did not say which 3 wires were on the switch. A three way switch has 2 travelers and one common. I am assuming the white wires were spiced together in the box. The new switch should have three screws. 1 darker screw and 2 lighter colored screws. The two screws of the same color would get the traveler wires and the lonely screw would get the common wire.

Answer 4

Have you check connector on the switch, the cables need to tight properly.

Even deferent lay out as long connector inside same numbers as old one you might use it.

You need to double check of cabling on connector I guest that wrong way.


Muhammad irwan
Siem reap
Cambodia