Posted by Heidi Schwartz
“Absolutely, categorically untrue. An urban myth.” That’s how National Lighting Bureau Chair Howard P. Lewis (Visioneering Corporation) describes claims that compact fluorescent lamps (CFLs) pose a fire hazard when they reach the end of their lives. Lewis, who represents the Illuminating Engineering Society of North America (IES) on the Bureau’s board of directors, dismissed the claim as “a vampire rumor: It feeds on fear and refuses to die.”
Ironically, the basis of the rumor might very well be the normal performance of well designed CFLs’ fire safety systems. In most CFL end of life situations, these safety systems remain dormant, Lewis said.
“Most commonly, CFLs get somewhat dimmer as they enter failure mode and then expire, or in some cases, expire with a popping sound similar to the sound made by an incandescent bulb when it ‘gives up the ghost,'” Lewis explains.
In some cases, however, capacitors, resistors, or other electronic components located in the CFL’s ballast may fail in such a way that they make a slight sizzling sound and/or cause odor or smoke. It’s even possible for the ballast housing to discolor or deform, principally because of the fire inhibiting chemicals incorporated into the plastic housing. Such reactions pose no danger, Lewis said.
“What it really is,” he notes, “is a demonstration of the CFL’s remarkable fire safety design working exactly as it’s supposed to, to protect consumers and keep them safe.”
According to Snopes.com, “[H]ealthy CFL bulbs may emit a bit of smoke and have burnt looking bases when they die, but that’s as it should be—there’s no fire danger to any of that and, indeed, the bulbs are functioning properly when they act that way.”
The Snopes Website also quotes the National Geographic Green Guide as stating CFL bulbs “burn out when the ballast overheats and an electronic component, the Voltage Dependent Resistor (VDR), opens up like a fuse in a fuse box, shutting off the circuit and generating heat and possibly a small amount of smoke. This might sound dangerous, but the VDR is a cut off switch that prevents any hazards.”
In some cases, the ballast’s plastic housing can melt slightly where the glass coil connects to the ballast, the Green Guide states, noting that this “is simply a sign that the heat is escaping as intended in the design of the bulb.”
Those who want a complete technical description of the process can download a free white paper published by the National Electrical Manufacturers Association (NEMA).