Electrical – the correct way to wire a 3 way switch where power comes into the middle switch

electricalmultiway-switchwiring

I found two books and neither had the diagram. Only I found two separate diagrams that did not work.

The setup:

  • Box 1 with 3 wire runs to box 2.
  • Box 2 has 2 wire power in, 2 wire to light and 3 wire to box 1

Both diagrams show Power (Black) to 3 wire (black), connected to common black screw in box 1 switch.

Power in Neutral (white) to light neutral (white/silver screw)

Box 2 switch Common black screw to Light (black/ brass screw)

Where they differ is in the Red and White from the 3 wire. One shows reds on left, whites on right; both switches. The other shows Red left box 2, red right box 1; white right box 2, white left box 1.

Both configurations trip the breaker.

I have checked ground connections, lines with multimeter, 3 separate switches, Checked tension and for micro holes/pinching, and checked the light.
The issue seems to be with the 3 way wiring.

I'm at a loss.

This is the diagram of what i tried, the other diagram was the same with the red and white in the far right box swapped… that didn't work either.

This Isn't working

Best Answer

You'll lose your mind dealing with all the red black white business. Get a 5-pack of colored electrical tape and start marking wires for their actual function. Always mark wires the same at both ends. Here is what's really happening in a 3-way.

enter image description here

First, the two traveler wires get marked yellow. There is no need to tell them from each other. So in the /3 cable, tape the black and white wires with yellow tape. That'll leave red, which is a preferential color for switched-hot.

On the black and white cable up to the lamp, mark both ends of the black wire with red tape, since it is switched hot. Mark the lamp's black lead red also.


The hard part is behind us. Now we wrap up.


On both 3-way switches, the yellow wires go on the brass screws.

On the near 3-way, the supply wire (black) goes onto the black common screw. (It's almost like someone color coded it, lol).

On the far 3-way, you have no choice: 1 wire 1 screw. Done.

All the wires that remain are white and red. Nut them by color: white to white, red to red.

Golly, that was easy! Or rather, we made it easy with our thinking cap and some colored tape.