Dimmable CFLs
Do I need these for my dimmer switch, or is it safe to use a regular CFL?
My apartment bedroom has a dimmer switch. Do I need to use dimmable CFLs with it or is it safe to use the regular compact fluorescents I already installed?
I know dimmable CFLs would be better but I have already paid to upgrade the original incandescent bulbs to regular (non-dimmable) compact fluorescent bulbs. Is this safe, or will the dimmer switch cause them to explode?
I have read that it's dangerous to use the dimmer switch on these bulbs so what I am wondering is, can I just leave the dimmer switch on high all the time, or switch it off, and will that cause a problem? Seems like that should be the same as just having a regular light switch.
As I mentioned, I've already spent money on the CFLs, I don't want to have to buy dimmable CFLs. I'm not going to dim them anyhow so I don't see the point of buying them.
Answer from Green Energy Efficient Homes
You can buy compact fluorescent lights that are designed to work with regular incandescent dimmer switches. These are known as dimmable CFLs. But as you say, you've already invested in regular ones and you don't want to buy another set of bulbs.
I do not recommend using regular CFLs on a regular dimmer switch. Even when you have the dimmer switch at 100% brightness, the current drawn by a standard CFL can spike on occasion anywhere from triple to five times the nominal current. In other words a 13 watt CFL which normally draws 83 milliamperes could draw as much as 245 milliamperes when attached to a standard dimmer switch at 100%, and up to 450 milliamperes when dimmed to 75%. The ballast is not designed for this amperage and components can overheat, potentially causing a fire. While the risk when the dimmer is at 100% is less than that at 75% you are still far exceeding the current capacity of the ballast. And there is always the risk that you or someone else will inadvertently dim the lights, increasing the risk of fire.
Over and above the fire risks, running the bulbs in dimmed mode on an incandescent dimmer will wear the bulbs out faster than normal. Interestingly, putting CFLs in enclosed ceiling fixtures also tends to break them down sooner - because they heat up more. This is precisely what happens to standard CFLs on a standard dimmer switch.
If you're living in a rental unit you can't really change the dimmer switch to a CFL compatible one without your landlord's permission, but these switches, which only a year or two were in the $70+ range, have come down to as low as $20 (be careful though, as some dimmer switches labelled as appropriate for CFLs actually require the CFLs to be of the dimmable type). The one pictured here, available on Amazon, is compatible with both standard and dimmable CFLs. Before you decide whether to upgrade the dimmer or switch back to standard incandescent bulbs, see my CFL savings calculator to figure out whether you'll actually save any money by going with CFLs. (Of course, the imminent demise of the CFL may make this choice moot, since these bulbs are already banned in some countries, states or provinces, and more and more governments are jumping on the incandescent 'ban' wagon!
If you decide to go back to incandescents, or replace the CFLs with true dimmable CFLs, please dispose of the bulbs safely as they contain a trace amount of mercury.
Note that you can't combine dimmable CFLs and incandescent bulbs on the same dimmer switch. Because the two types of bulbs respond differently to the change in voltage created by the dimmer switch, one bulb will dim slightly while the other will practically go out.
More information from Green Energy Efficient Homes
- Dimmable compact fluorescent bulbs
- How do fluorescent lights work?
- Buy dimmable CFLs from Green Energy Efficient Homes
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