It got really old here this week, so I broke down and put a heat lamp in my coop, despite having never previously doing so. Within a day it had blown. I replaced it with another 250 watt bulb and it blew in 5 minutes. Since I was now out of heat lamps and don't really care to just keep blowing them, I put a 100 watt white bulb in. That lasted 36 hours before it was not working. Any suggestions on the cause here? This weather is past now, but I just want to know the cause for future reference.