I would like to install a duk to dawn photo cell to my outside carriage lights on my garage. Do I need to install this so the light from the fixture does not shine on to the photo cell. If the light shines on the photo cell will it turn it back off? I can put the photo cell on the bottom of the mounting but that is were the frosted lamp hangs past. I have an option to fit it at the top of the fixture base above the lamp but it will be much more noticeable. Can anyone advise me on my best choices and if the light from the lamp will effect the operation of the light. I have looked for info on how photo cells work but my searches have not brought any results. Any advise would be appreciated. Thank You.

Yes, the light from the fixture will turn off the photo cell if shined on it. The photo cell cannot tell the difference between naturel daylight and artificial light. Most carriage lights that come with photo cells have the photo cell built into the fixture below the light and the base of the fixture blocks the light from shining on it or the back side of the fixture is something other than glass. A photo cell does not have to be mounted on the fixture. It's location is limited only by the type of photo cell you purchase and the wiring necessary to connect it.

If you have conduit and can get an extra wire from light to another location, photocell could be located there.
Instruction usually say to point the photocell to the North, north is not always possible.