How do I wire a timer to an electrically held lighting contactor?

Your lighting contactor will have 2 coil terminals, typically marked A1 and A2.  If you have a 120Vac coil, you would land your neutral on terminal A2 - and leave it there all the time - it should not be switching.  Then run your hot 120V through your normally open contact on your timer.  The other side of this N.O contact should be landed on A1 such that when your timer actuates (turns on) the contact closes and sends the hot to A1. The contactor will pull in when it has the correct voltage across A1 and A2. If you have a different voltage coil, you still wire it the same  - one leg goes to A2 and stays there - other leg goes through your timer and back to A1.  This is assuming the timer contact is maintained the whole time you want your lights to be on.

For mechanically held contactors or 3-wire control wiring issues please call us at 1-800-ETN-CARE and select the technical support option, then select contactors technical support. We can assist you over the phone.