Hi
I’m using an 1157 automotive bulb in my enclosure with a button type thermostat and haven’t had any problems. I added the heater as the Fluke 411D and 414D are only rated down to 32 def F (0 deg C). My enclosure temperatures can be seen at:
http://mikeymsweather.com/extrarealtimegraph.gif
Cheers
MikeyM