Utilitec 7-day timer will only replace single-pole switch.
Single pole switch has two brass screws and a ground screw.
Links below show wiring for both Utilitec 7-day timershttp://waterheatertimer.org/Program-wire-Utilitec-0192773.htmlhttp://waterheatertimer.org/Program-wire-Utilitec-0141224.html
If this is not your timer, then add a comment and specifically state which timer you have and which wires came off which screw on old switch.
The best way to start is to identify exactly which wires came off old switch.How to wire
1) Timer-green-wire connects to bare ground
2) Switch has 2 insulated wires. Take switch wires and connect them to timer-black-wire and
timer-red-wire. Choose either one for now.
In back of electric box are white wires twisted together and covered
with wire nut. Connect timer-white to these wires.
4) If electric box does not have white wires described above, then
connect timer-white to bare ground, along with timer-green wire.
Turn on electricity, and push ON-OFF button. If lights come on, timer
is wired correctly. If lights do not come on, then reverse timer-red
and timer-black wires.
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