Our house has some directional external lights (the mount allows us to pivot the fixture).
I just tested out one of them today by putting in a bulb. The bulb flickered (it's a good bulb) when I turned it on and it did not stay on.
I'm not going to fix it right now.
Do I need to worry about rain shorting out the fixture if I don't put a bulb in the socket?
It would only short out if the switch is in the ON position right?
Do outdoor rated light fixtures mitigate against this?
Normally, old style exterior flood lights are mounted under the eave of the house protecting them from the rain. They also had a rubber gasket to seal against the flood lamp.
If yours are mounted on the gable wall of a house/garage they should be pointed down anyway which keeps the socket from collecting water even if it's empty.
Unless the socket fills with a considerable amount of water it won't short out. And if it does it will most likely trip the circuit breaker before anything bad would happen.
Rest easy.
