One Source For All Your Replacement Lighting Requirements
One Source For All Your Replacement Lighting Requirements
call 1.800/223.3808
Are Halogen lamps really hotter?
The truth is that 1 watt of light is equivalent to 1 watt of heat. This means that a 100 watt incandescent light bulb produces 100 watts of heat. The equation holds constant whether the lamp is incandescent, halogen or fluorescent. All of these lamp types operate at below atmospheric pressure and share some common characteristics. These lamp types all use the lamp envelope (exterior housing) to transfer heat. Thus the key to lamp heat is found by measuring the temperature at the bulb wall. This means that the temperature of a smaller lamp envelope with less surface area will be higher for a comparable wattage bulb with a larger lamp envelope. The exception to this rule comes with the small envelope halogen lamps in the T2, T3 and T4 sizes because their housings are manufactured from quartz rather than glass. Quartz is more effective at transmitting heat than standard lamp glass so skin contact with these lamps while they are operating will result in serious burns. Ultimately, fixture design and the attendant wattage limit will dictate the operating temperature in a particular application but there is no inherent danger in replacing an incandescent bulb with a halogen of equivalent wattage.
High pressure lamps such as sodium or metal halide present a separate set of issues. The lamp's outer envelope is glass but the interior arc tube is made of quartz or ceramic and is pressurized above typical atmospheric pressure. Operating temperatures are quite high with some in excess of 500 degrees at the arc tube. These lamps must be shut down and cooled for an extended period of time before removal and replacement. This is not an application that has much penetration into the residential market as of today but it is likely that low wattage ceramic arc tube bulbs may have an increasing presence in the future.