I have one of those common mercury vapor yard lights found on most farms. Early last spring it started to refuse to light and I thought the bulb was dead. I was not going up there with snow still on the ground, so I lived with out it, and just put a portable light on the pole. All of a sudden the yard light started to work again, and has worked every night all of the later spring, and all summer. All of a sudden the weather is getting cold again, and the light will not turn on. However, if I shut off the switch for a 30 seconds and flip it back on, the light starts and works all night long. A few days ago, the weather warmed up again, and the light worked again. Tonite it's very cold and it will not light even after I flip the switch.
This is about the stupidest thing I have ever seen. Why the heck would it work when the weather is warm, and either struggle or refuse to light when it's cold weather. This is just plain rediculous.
It's not the switch or power source, I checked the power and replaced the switch. This almost seems like a challenge for an electrical engineer....