I purchased an Intermatic Model EJ500 Self Adjusting Indoor Wall Switch Timer. I want to use the timer to automate my front porch lights. The switch I am replacing is one of three 3-way switches that control the lights and is in the middle of the circuit.

I have two sets of wires coming to the current switch. There are two red and two black wires that connect to either side of the 3-way switch (one black and one red on each side) and two white wires that connect to each other but not the switch.

The instructions say to locate the common wire and connect the black wire from the timer to the common wire. What are my common wires? Then the instructions say to connect the other two wires from the timer, one blue and one red, to the other wires coming out that are not the "common" wire. Please help.

Also, I assume I am going to have to install a jumper cable on the other two 3-way switches so any help you can give me on that would be appreciated. Do I need to install jumpers on both of the other 3-way's or just one of them?