Light switch timer for outside lights

We just moved into a house that has outside patio lights controlled by 3 different light switches. I want to replace one of the light switches with a digital timer. What type of light switch timer do I need? 3 pole? 4 pole? And does it matter which light switch I decide to replace in the circuit?

• All the lights are controlled by 3 switches, or there are 3 switches that each control some of the lights? Apr 7, 2015 at 12:49

It matters which one you replace, because that will determine which type of timer you need. One of those switches is going to be the "middle" switch, between the other two circuit-wise. That middle switch is a four-way switch, the two outside switches are three-way switches. You can determine which is which visually is you don't know the circuit layout - the three-ways will have three wires plus a ground, the four-way will have four wires plus a ground attached to each switch.

This is a simplified and idealized example of the circuit you're dealing with:

• Great explanation and diagram, John. So... all I would need to do is to find which switch is the 3 way, and then use a 3 way switch timer? Apr 8, 2015 at 10:20
• There will be two three-way switches as shown here. Find either one of them, and if you can find a three-way switch timer - I've neither seen nor heard of such a beastie - replace the one you've found.
– John
Apr 8, 2015 at 11:41