Can I use a CFL or LED bulb in an outside flood light type fixture that is hooked up to an in-wall Intermatic timer?

November 10, 2012 2:41 PM

Can I use a CFL or LED bulb in an outside flood light type fixture that is hooked up to an in-wall Intermatic timer? I was told no but I would like to confirm. If that is the case, I'd love a short explanation in plain English. I tried Googling but I'm still confused.

I had an electrician install a new flood light type fixture outside that is on a timer that part of my light switch (brand is Intermatic). I thought I could use energy efficient bulbs in it but the electrician told me no. He could not explain why to me and I wonder if it is because he didn't want to go back on his ladder to change out the bulbs. He had really poor communication skills overall and I never got a good answer from him.

Now those bulbs have burned out and I want to know if I can replace them with CFL or LED bulbs.

SO:
1) Can I use LED or CFL bulbs?
2) If not, I'd love to understand why I can't!

posted by dottiechang to Home & Garden (11 answers total)

The only experience I have with CFLs or LEDs not working is when you're using a daylight detector. Some of them can be touchy, due to the way they cycle the power to the bulb. If your in-wall light switch is just a x hour to y hour timer, it should work.
posted by jeffkramer at 2:44 PM on November 10, 2012

Yes, you can. You can't use a CFL or LED in something that may not send a full 120V to the bulb, i.e. a dimmer or a daylight detector. A normal timer is fine.
posted by jferg at 2:48 PM on November 10, 2012

It may say here.

Generally, switches and timers that offer dimming capability are not good with LED/CFLs unless the LED/CFL specifically says it's compatible. If the switch simply goes ON and OFF, LED/CFLs should probably be OK.

Kind of the same with daylight detectors. The ones that gradually turn on as the outdoor light dims won't work. Those that turn ON completely after a certain threshold are OK.
posted by 2N2222 at 2:50 PM on November 10, 2012

Best answer: If it's a timer like this one (or any electronic timer that only has two wires) then Intermatic says only incandescent bulbs.

Reason: The timer is operating without a neutral by doing something funny with the power and that will both damage the ballasts in anything but incandescent light and also requires a minimum power draw to work. A CFL or LED often won't draw enough power to allow the timer to function.

If you replaced the timer with a unit that uses a neutral then you could put non incandescent lights in the fixture but you probably don't have a neutral in the wall where the timer is located.
posted by Mitheral at 2:55 PM on November 10, 2012

Response by poster: I realized that I had to take the timer out of the wall to find the model number, EJ500, which only works with incandescents according to this chart.

Thanks for helping me think about this and helping me understand why CFLs and LEDs won't work.

Very frustrating because I made it super clear that I wanted to use energy efficient bulbs! Would love recommendations for in wall timers that you have used that work well with CFLs and LEDs.

Thanks!
posted by dottiechang at 4:19 PM on November 10, 2012

Just a note in passing: the wire the electrician used for the fixture probably has a neutral line in it that is not connected. This is a matter of cost of materials since most wiring requires the neutral line, he probably used wire he had rather than something special for this job. Find an electrician that you can talk to and arrange to have the fixture rewired when you replace the timer.
posted by ptm at 4:35 PM on November 10, 2012

I use this Honeywell timer with CFLs and it works fine.
posted by zsazsa at 4:57 PM on November 10, 2012

Do you have an expendable, dimmable LED light you could test? Sometimes manufacturers error on the side of caution since it's more difficult to explain why one LED might work and another might not...

Someone else please correct me if you think this is a safety issue...
posted by NoDef at 5:21 PM on November 10, 2012

Two-wire timers like that operate by actually passing a very small current through the bulb filament when the bulb is off (small enough that the bulb does not visibly light up). Gaseous bulbs can't pass any current through unless they actually light up.
posted by Doohickie at 6:29 PM on November 10, 2012

Response by poster: I saw there is a red, blue, black and copper wire when I pulled it out to find the model number. The red one is capped. Is one of those the neutral wire?

THANK YOU for all your helpful comments. I appreciate them.
posted by dottiechang at 9:16 PM on November 10, 2012

Since this is an outdoor light, don't forget that most CFL bulbs don't work in temperatures below 40 F. You can use LEDs or Cold Cathode CFLs instead.
posted by monotreme at 10:51 PM on November 10, 2012