If I have a contactor that I want to use with two separate control sources, on a site with a single phase power source, is it possible to connect two 120V control signals to the contactor coil, potentially live at the same time and connected to the same source, without causing a short, or damaging any equipment? The circuit is being designed to automatically turn on security lights at intervals set on a time clock, but with the addition of a manual override to turn on the lights as needed. I am not an electrician, but the work will be completed by a certified electrician once the planning for the building upgrades is complete. I'm just trying to understand how this would work. My understanding is that since the power is coming from the same breaker panel and the same power source, the two control voltages should always be in phase, eliminating the possibility of constructive and destructive interference. I would think that this setup would be considered a parallel arrangement? Meaning there would never be more than 120V supplied to the coil if both inputs were on, but the current available to the coil would be higher? Or would that supply too much current to the coil and cause problems? I'm just curious, I don't know how the electrical contractor will actually hook everything up when the time comes, but I have to admit I find this concept rather fascinating and I'd like to know a little more about it.