I have a mercury vapor (farm) yard light on a pole.
It always works fine in warm weather, but once the temperature gets
below about 40deg., it dont always turn on. However if I flip the
circuit breaker off and back on, the light works. Last winter it
started doing this most irritating thing. I bought a new bulb
thinking the bulb was failing. Before I got the bulb replaced, the
weather warmed up and it has worked non-stop all spring and summer, so
I never replaced the bulb. Now the weather is getting cool and it's
once again not working every night, until I flip the breaker. Last
night we barely had frost and the light would not come on till I
flipped the breaker. What the heck is causing this? I know there are
only 3 parts, the bulb, ballast, and sensor. But which would be
affected by temperature?