The Pass and Seymour RT1 and Wattstopper-brand RT-series and the Utilitec RT1 are countdown timers.
You push the button and the timer turns on the Load (light,fan, motor) and the timer begins a countdown. At the end of the countdown, the timer turns off the Load. Excellent way to make sure lights and fans don't stay on all day by accident.
Your existing switch has two wires. The switch does not have an internal clock like the timer.
The timer has one additional wire because the internal clock has to have power just like your electric alarm clock. Manual says
Black Hot wire connects to timer-black wire
Black wire to Load connects to timer-red wire
Timer-white wire connects to other white wires in the box (these wires are usually twisted together and covered with a wire nut) Summary
: This information means the two wires that came off the switch connect to the timer black and timer red wires.
Which goes to which? You can connect them either way, and if it doesn't work, simply switch the pair with each other. Or you can turn on power and test to see which one has power, and that is the Hot wire that connects to timer-black.
Now let's focus on the timer-white wire ... this is the wire that allows the internal clock to work.
Look inside the box where switch came out. Do you see two or more white wires pushed to the back of the box and covered with a wire nut?
The whites covered with wire nut are the Neutral wire and the timer-white connects to them.
*If your box does not have those white wires, then timer-white can connect to bare ground until the day you hire an electrician to drop additional line into box. Connecting to ground is NOT code and not recommended but it will work.Here's a neat trick for connecting the white wires together
Pull out the whites so you can work on them.
Take off the wire nut.
Hopefully the whites will be twisted together as per National Electric code so when you remove the wire nut, the whites stay together.
Now go back to the timer-white wire and remove about 1-1/2" of insulation off the timer-white wire so you have a fairly long bunch of stranded wire
Hold the whites together so the insulations match up
Wrap your stranded wire around the solid copper wires like a candy cane all the way to the end
Put the wire nut back on real tight
Then pull on your timer-white wire to make sure it will not come loose from the wire nut
Push the wires to back of box.
Connection is done.
See how to twist solid copper wires togetherhttp://waterheatertimer.org/How-to-twist-electric-wire.html
See wire nutshttp://waterheatertimer.org/How-to-select-right-wire-nut.html
See inside your main breaker boxhttp://waterheatertimer.org/See-inside-main-breaker-box.html