I have a house with three lights on the front of the house. There is one by the front door and two on the front of the garage. All three lights are on one light switch just inside the front door. I want to put a motion sensor light in front. If I put a motion sensor light on the one by the front door will it activate the other two lights or will I need a motion sensor light on all three lights? Help and Thanks.

Power will be turned on to all lights if they are all on one switch. Easy cure is to just put motion on all lights independently except for the garage and those two can just use the same motion detector.

You may also want to mark the switch (do not turn off) or some such language or bypass the switch so that power is always applied to the circuit since they will now be automatic. Make sure you also mark the circuit breaker like same so if service is ever needed the repair person will know which breaker feeds the outside motion sensor lights.

Ion sensor lights have been problematic, especially the cheaper ones. One issue with the lights is the "so called always on mode". Some use the short flick of the switch to allow the light to stay on indefinitely. Unfortunately, this is the same thing that happens in a power glitch.

In order to be immune to turn on, they might use two technologies in the detector. I don't have extensive experience with sensors that work or don't work, but I do have a battery operated detector with wireless transmitter in the living room. The light is a night light. This is an elderly motion activated night light and has worked very well, except that the photo sensitivity for when motion is not supposed to activate the light is not low enough.

Three independent motions might be better, however if you wanted to have 1 motion control the other 2, would probably be the front door, The 2 outer lights hopefully go to front door light, or front door switches, if this is in conduit, you could pull extra wire to allow relocation.

To the original poster: if you're talking about motion sensor lights like this:

http://www.homedepot.com/catalog/pro...ec143a_400.jpg

The motion sensor in the fixture is only designed to control the two bulbs that are part of the figure. You could wire it to other fixtures, but then you could only use low wattage bulbs like CFL's and if someone put 150 watters in by mistake, they'd fry it. I'd suggest 3 separate motion sensor lights.

I have hooked 3 together like that, and had the three reds all connect to each other, so whichever detected motion, all would light. Wattage of bulbs cannot exceed motion detector light wattage.