What are lamp BTUs?
British Thermal Units (BTUs) are the measurement of heat output. One BTU is the heat that will raise the temperature of one pound of water by one degree Fahrenheit. It is approximately the amount of heat generated by burning one blue-tip kitchen match. There are approximately 3.4 BTUs per watt per hour. High bulb temperature usually does not affect the life of the lamp unless the temperature is extreme. The filament of an incandescent lamp operates at a very high temperature (nearly 4750 degrees Fahrenheit for a 200-watt standard lamp). An increase of a few hundred degrees in bulb temperature does not noticeably increase the filament temperature, and there is practically no effect on the lamp life or light output. Glass in most general service bulbs withstands 700 degrees Fahrenheit safely.
