CFL on photo on/off?

The problem is that these photosensitive devices draw their power through the lamp, so there's a trickle of current flowing even when it's supposed to be off. With an incandecent lamp, this doesn't matter. But with a CFL, if you're lucky, the result is the lamp flashing on momentarily like a strobe periodically but no damage to it. :)

Makes sense, thanks Sam.

I hedge my bets: In a 2 lamp device I use 1 incandecent and 1 CFL. :-)

Jonesy

Good solution! The only concern would be if the photosensor device doesn't switch (mostly) on or off cleanly.

Hi!

I'm glad someone brought this up, because there is something I'd like to know.

I've got an outdoor porch light on a post that has a 100 watt equivalent CFL bulb in it. The fixture itself is made of cheap plastic, and the light is on fairly often, so I feel better using the CFL as opposed to a 100 watt incandescent. (However, I haven't noticed a maximum wattage rating on the fixture itself.)

I'd like to switch this light via photocell.

To prevent any possible "abuse" to the CFL, I'd like to have the photocell device turn a relay on and off. Is it possible to do that, or would it result in unacceptable behavor (buzzing, etc) from the relay?

If it won't work, I could always use a timer of some sort.

William

On 3/12/2010 7:02 AM William R. Walsh spake thus:

Keep in mind that CFLs are often not good candidates for this kind of application, because the length of time they take to warm up is often the same as the length of time they're on, so they don't do a very good job of lighting up the area you want illuminated. For an intermittent application like this, it's probably just as cost-effective overall just to use a good old-fashioned incandescent lamp.

But it would be ok for a dusk to dawn security light?

On 3/12/2010 10:52 AM Meat Plow spake thus:

Yup, that would be a good place for a CFL. (Assuming it plays nicely with the controller, that is.)

They sell dusk to dawn security lights made for CFL. My dad installed one with a 65 Watt CFL he bought at Lowe's or Home Depot for his place. It was several years ago and he doesn't remember, for sure. He also bought a smaller one, to light the sidewalk to his driveway.

You shouldn't have any problems running a relay with a photo-cell.

Most photodensors use a relay. No different from a switch.

greg

That said, I don't remember if there was a warning, but I can hear a click on mine. I used to keep it on, and would last a year or more. I'll see how long it lasts not with a sensor, along with two led spotlights.

greg

I'm not sure I'd bother. For example, we have a bathroom with no windows in the middle of a dark hallway. I just out in a CFL and leave it on.

Lights up the room, lights up the hallway.

At what I pay for electricity it costs under $9 a year, which is less than the cost of a light operated switch or timer, and probably less current than a timer anyway.

Geoff.

Even the kind that screw into a light fixture?

Outside Lamp post for my mom. She says traditional bulbs don't last long enough and there is no way to enable it in an always on mode. Besides she is too frugal to want to let it operate 24/7. She's the kind of person who washes out tin foil and reuses it :)

There are standard bulbs made for use in these places. They are made with thicker filaments so they last much longer. Another trick is to use a 240 volt bulb, they run at much lower intensity (and are that much less efficent) but they supposedly last "forever".

Geoff.

Many neighborhoods are too dark at night. My old neighborhood in the 60's, My mother complained about no street lights. Realitor said there is enough light from the neighbors outside lights, and it was true. Every fourth house also had a gas lantern. That neighborhood is now too dark. If those people started using CFL's they could afford to keep them on.

greg

I also like to complain about light that shines in my eyes. Much of the light from lights goes up into the air where its useless, and also into my eyes.

greg

While not being efficient I much prefer the warm whites, but they can be more efficient seeing in foggy conditions.

I once built a lantern with a variable light control. A resistor. Shining the light at full brightness into Lake Erie showed nothing. getting it nice and dim, you could see right through the water.

greg