Adding a 4 way switch to 2 existing 3 Way switches

Currently I have 2 existing 3 Way switches

1. Box 1 has 14/2 from power source and a 14/3 run to box 2
2. Box 2 is 14/3 and 14/2 that runs from the light fixture.

I have added an additional 14/3 to box 2 and run that to box 3. My question is how do I make the connections in box # 2. Do I need to change box 2 to a 4 way switch and then will box 3 be a 2 way switch?

This diagram describes what you want (source), it's just complicated by the box positioning. Normally you do it in a series

1. Three-way
2. Four-way
3. Three-way

I think you can tweak this to make it work.

In Box #1, the incoming hot (the 14-2 black) should connect to the black screw of your switch. Wire the black from the 14-3 to your 14-2 neutral white.

Put your 4 way into Box #2 and wire it as shown in the diagram, but instead of nutting the black wires together, nut the white wire from your fixture (14-2) to one and the black to the other (it doesn't matter which you connect to).

• Not working. Here is what I did. Box 1. Wired as your suggestion.. Box 2. My 2 red wires are connected to right side of 4 way switch Black from lights goest to left top of 4 Way. White from new 3 Way wire goes to 4 Way bottom left. White from lights goes to black of the existing 3 Way wire Black from new 3 Way wire goes to white of existing 3 Way wire. results are.. box 2 not changing the on or off status. If lights on and you flip switch in box 2 they remain on and if off they stay off. Result vary depending the position of switch in box 1 or 3 – Larosa Jan 7 '17 at 14:48
• It sounds like you wired some of the light's 14-2 into the 4 way. They should only touch the black wires on the 14-3 connections. The rest of the wires should be as the diagram specifies – Machavity Jan 7 '17 at 17:56

Overcomplicating things. All you need to do is find the 4 wire that currently runs from one of your 3 way switches to the other. You will need to cut/break this and add the 4 way switch in between. The 4 way switch will have 2 terminals marked IN and 2 marked OUT. The black and red travelers from both sides of the cut which are now coming towards the 4 way from both of the 3 ways, will go into the IN on one side and into the OUT. Done! My advice worth price charged.

• No 4-wire cable was mentioned in the question. – isherwood Jun 20 '18 at 15:14
• 14-3 is a 4-wire cable. Red, Black, White, and Bare. – Dustin Brooks Mar 18 at 2:02