Photo-cells and CFLs, Part II

[nielloeb]

Let's try this again. I have an outdoor floodlight fixture with a photo-cell to turn it on at dusk and off at dawn. It is not compatible with CFLs. If I cover the eye so it thinks it's always dark and therefore will always be on, will a CFL work, or is the circuitry different such that the CFL will have a shorter life, even though it will always be on? Part II: If, for the previous question, it will work, I will add a screw-in photo-cell that works with CFLs for only $8. Then, it will be on only at night and will be cheaper than buying a new fixture.

[LouB]

Q 1 is easy. Try it. Q 2 A little math is suggested, Cost of power to that CFL, assuming CFL rating is accurate (ie 13 watt or whatever) times hours of elec saved

[DD_BobK]

rewire the fixture with a non-photo cell socket ,....add the CFL rated screw in photo cell socket

OR

if the photo cell is a remote one, jumper it

cheers Bob

[jamesgangnc]

You need to bypass the photo-cell. Forcing it on does not solve the problem. Or replace it with one that is compatible with cfls.

[hrhofmann]

The usual photocell lights may not turn on fully at twilight conditions, and the CFL's don't like that. If the photocell operates a relay, so the light is fully off or fully on, then the CFL will work ok.

[jamesgangnc]

It's very unlikely that the photocell operates a relay since they are pretty much never used in those things. Mechanical failure rate is too high. It probably has a triac that is not compatible with cfls.

[hrhofmann]

ide quoted text -

I have a couple at my house that have the relays, you can hear a click as the light varies up and down. But, I agree that type are in the minority.

[James]

I have bought three regular photo-cells for regular bulbs in the last month, and only one of them has worked.

Is there a huge failure rate for these things ?

James

[Tony]

I bought 3 lamps from the Borg without even knowing they have photocells in them. I could turn that feature of but I left it set to light dusk to dawn and all three CFL's have been working for months now. If the cheap photocells in the lamps go bad, I'll bypass the photocells, wire them direct, and put them all on one heavy duty photocell. And if that doesn't work, I'll make the photocell turn on a relay which will give power to all three lamps, I know that WILL work.

[hallerb]

OLDER CFLs died fast on my pole light with photocell.......

newer ones live happlily and last a long time. whatever failed must have been addressed..........

[hrhofmann]

The "photocells" in light-sensitive switches or fixtures or whatever you want to call them are normally variable resistors whose resistance changes with the light that falls on the sensor. This in turn is used to control a semiconductor called a "triac" which can control the output, either directly, or by operating a relay. The relay, because of its mechanical nature, is either on or off. But, if the triac output is connected directly to the output/lamp socket, in transitional lighting levels, the triac will only be partially conducting, just like a light dimmer, and that is what the CFL's don't like.