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Fire Safety and Compact Fluorescent Lights (CFLs)

August 26, 2011

The EPA and Dept. of Energy estimate that by changing American homes from incandescent bulbs to compact fluorescent lights (CFLs), we could save enough energy to light 3 millions homes for a year.  There is no doubt that CFLs are far more efficient at producing light than incandescents.  Nationally, we’re headed toward phasing out incandescent light bulbs.  Are there safety concerns with CFL bulbs?  That question has come up and we did some research on the topic.

An incandescent bulb creates light by running current through a filament until it glows.  That’s been the standard for over 100 years.  CFLs run current through a mercury vapor.  This current causes the mercury to emit ultraviolet light which causes a phosphorescent coating inside the bulb to emit visible light.  Both types of bulbs give off energy, typically measured in watts.  The problem with incandescent bulbs is that much of the energy given off is heat energy.  CFLs outperform incandescents because a much higher percentage of energy given off is visible light energy.  A typical 60 watt incandescent will produce about 14.5 lumens of light.  A typical CFL gives off around 120 lumens of light.  You can see why CFLs are more efficient sources of light.  In fact, Popular Mechanics (2011) estimates CFLs are about 70% more efficient in converting energy to light rather than heat.

But what about safety?  Incandescent bulbs produce a lot of heat and have been the ignition source for many fires.  In fact, incandescent light bulbs have often been used as heat sources (heat lamps for reptiles, incubators for poultry, even the Easy Bake Oven toy).  CFLs do not produce as much heat and should not cause the fires that we typically see when incandescent bulbs are used incorrectly.   In fact a 60 watt CFL bulb will produce way less heat energy than a 60 watt incandescent.  That doesn’t mean CFLs are entirely hazard-free.

One issue is that light bulbs and light fixtures are categorized by wattage or the work that could be done with the energy (a combination of both heat energy and light energy).  Using watts as your unit of measure was a good comparison as long as we were only talking about one type of light bulb.  Because CFLs produce more light and less heat, comparing their wattage ratings to incandescent bulbs will be comparing apples to oranges.  Most light fixtures were manufactured with a maximum wattage rating based on incandescent bulbs.  People have asked if they could use a larger wattage CFL in their light fixtures.  I’ve not yet seen the industry develop a unit of measure for comparing the amount of heat a light bulb gives off.  Most CFL packaging discusses lumens, which is the amount of light given off.  So can you use a 100 watt CFL in a light fixture rated for a 60 watt incandescent without starting a fire?  I wouldn’t do that.  We need to wait and let the facts get in to see how the industry measures heat output vs. light output of CFLs before we go doing the math ourselves.

Additionally, fluorescent light bulbs require a ballast to start the process up.  Older ballasts sometimes failed catastrophically causing fires and there have been two recalls of CFLs due to ignition issues. Newer electronic ballasts in modern CFLs are designed to preclude that from happening.  However, the base of a CFL bulb may discolor from the heat released when the ballast burns out.  Or the bulb may make a popping noise.

Another concern is how the mercury inside CFLs will harm the environment.  Mercury is a heavy metal (US Dept. of Labor, 2009) and a cumulative poison that impacts the central nervous system.  Two things could be problematic:  breaking a CFL bulb and disposal.

Light bulbs get broken.  How much mercury will you be exposed to if you break a CFL?  Home Depot (2010) indicates a single CFL will contain 4 milligrams on average.  If you’re old enough to remember mercury thermometers, one of those typically held about 500 milligrams of mercury.  That being said, EPA (2011) recommends the following steps for cleaning up a broken CFL bulb:

  • Have people and pets clear the room.
  • Shut off any central heating or air conditioning, open some windows and air out the room for 5-10 minutes
  • Clean up the glass and any powder material, placing them in a sealable container
  • Place the cleaned up materials outside in a safe location until it can be taken to a household hazardous waste recycling facility.

CFL bulbs should not be thrown into the trash.  Throwing millions of CFLs into landfills may create a heavy metals contamination problem for the environment.  Once again, however, CFLs have very little mercury inside.  The Natural Resources Defense Council (2008) reports more mercury in a standard watch battery than the average CFL bulb.  CFLs can be properly disposed of at the North County Transfer Station, 22123 N. Elk-Chattaroy Road.  Additionally, EPA reports that Home Depot, Lowe’s and Ace/True Value will accept spent CFL bulbs, however, not every store nation-wide is participating so call first to check.

The bottom line is that CFL bulbs are more efficient at converting electricity into visible light.  They do not produce as much heat as incandescent bulbs.  All in all, CFLs should present fewer fire hazards than incandescent bulbs, but they do need to be disposed of differently.

CFLs are pretty new and questions will arise as we all use them more.  If you’ve got questions, give me a call at 466-4602, or e-mail me at, or leave a comment on this blog.


Home Depot. (2010). Everything you need to know about CFLs.  Retrieved August 25, 2011 from .

Masamitsu, E. (2011).  The best compact fluorescent light bulbs:  PM lab test [Electrnoic version].  Popular Mecahnics.  Retrieved April 18, 2011 from

Natural Resources Defense Council. (2008).  Compact fluorescent lights are safe for your home.  Retrieved August 25, 2011 from

United States Department of Labor. (2009).  Toxic metals.  Retrieved April 18, 2011 from

United States Enviornmental Protection Agency. (2011).  Cleaning up a broken CFL.  Retrieved April 18, 2011 from


From → Fire Prevention

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