dimmer switch on dust to dawn light

[jetlag]

I got a call from customer that said another electrician tried to install an dimmer on his yard light but it would not work and he had to take the dimmer back out. I told him I could do it . I was hoping there was a hot line in at fixture but my luck was not.. I had to run hot line in because photo switch must have full 120 v. Then the two wires to switch are changed to be travelers to break the hot between photo relay and fixture, now he can dim his fixture

 

[cadpoint]

I'll go negative

I'll go negative

Congrates on your savy wiring! I frankly don't think you can have both in my mind and in your case...

I'll just say that the photocell was not built with a dimmer in mind! JMO!

I know that in most cases there's a circuit board in there and playing with
the juice to a board(even down line) is not always a good thing.

Let me state the default statement and defer to 110.3, depending on the usage your'll be back there with-in the season... your wireing diagram of a photocell doesn't imply a dimmer.

They could have changed lamps, they could have tried other things like LV... Maybe you should think of some alternate means to illuminate. (see line above)

Electrical work is pretty easy, just hard to do at times with-in customer wishes. Again U did it and congrat's

 

[Dennis Alwon]

The photocell works fine as long as the dimmer switch is on the load side of the photocell. The switch will, of course, need to be on for the lights to work.

Makes you feel good when you solve something you never did before, doesn't it. Congrats.

 

[Jim W in Tampa]

So they wanted this why ? How long will it take them to recover the cost of the install by dimming the light ?
There are better ways to save on energy like LED lamps.

 

[hurk27]

If it is a thermo type of photo cell the dimmer can reduce the current going through the photo cell and this can cause the lamp to stay on, but if the photo cell is a relay type then as said placing the dimmer on the red lead will work just fine.

 

[jetlag]

Thanks jim

Thanks jim

So they wanted this why ? How long will it take them to recover the cost of the install by dimming the light ?
There are better ways to save on energy like LED lamps.

Its not the cost, it is a doctor that loves to dim the lights on the whole place. For a romantic look when he drinks his wine with lady friend.

 

[jetlag]

Thanks hurk

Thanks hurk

If it is a thermo type of photo cell the dimmer can reduce the current going through the photo cell and this can cause the lamp to stay on, but if the photo cell is a relay type then as said placing the dimmer on the red lead will work just fine.

I dont follow you . No matter what type of cell if you supply 120 v to cell which I did , 120 v will go to lamp and this lead can be dimmed.

 

[jetlag]

Thanks Dennis

Thanks Dennis

The photocell works fine as long as the dimmer switch is on the load side of the photocell. The switch will, of course, need to be on for the lights to work.

Makes you feel good when you solve something you never did before, doesn't it. Congrats.

Yes this was a first for me and never heard of it before. We learn something everyday.

 

[jetlag]

thanks cadpoint

thanks cadpoint

Congrates on your savy wiring! I frankly don't think you can have both in my mind and in your case...

I'll just say that the photocell was not built with a dimmer in mind! JMO!

I know that in most cases there's a circuit board in there and playing with
the juice to a board(even down line) is not always a good thing.

Let me state the default statement and defer to 110.3, depending on the usage your'll be back there with-in the season... your wireing diagram of a photocell doesn't imply a dimmer.

They could have changed lamps, they could have tried other things like LV... Maybe you should think of some alternate means to illuminate. (see line above)

Electrical work is pretty easy, just hard to do at times with-in customer wishes. Again U did it and congrat's

Thanks but I disagree, The photo said cell couldnt care less what you do with current once it sends it to the load. You can unsrew one bulb . There is no difference in a 20 watt bulb and a100w bulb with a variable resistance

 

[cadpoint]

Thanks but I disagree, The photo said cell couldnt care less what you do with current once it sends it to the load. You can unsrew one bulb . There is no difference in a 20 watt bulb and a100w bulb with a variable resistance

Sitting corrected, it won't be the last...

 

[jetlag]

Thanks cad

Thanks cad

Sitting corrected, it won't be the last...

Ive been there many times but I usually try to argue in vain so not have to admit. Ha Ha

 

[Jim W in Tampa]

Its not the cost, it is a doctor that loves to dim the lights on the whole place. For a romantic look when he drinks his wine with lady friend.

Tell him to drink a few before she gets there and then light a candle LOL

 

[hurk27]

I don't follow you . No matter what type of cell if you supply 120 v to cell which I did , 120 v will go to lamp and this lead can be dimmed.

A thermostatic type photo cell has a small heater element that heat a bi-metal strip type N/C contact, this heater and the photo cell are in series with the load, if the current draw is not enough to keep the heater hot enough then the contacts close keeping the light on, this will happen if you try to use a CFL that is lower then 6-9 watts (depending upon manufacture), if you ever replace a bad lamp that is controlled by one of these types or if the power is removed the lamp will turn on as soon as you screw it in, or turn the power back on, then the heater will heat up and turn it back off, this is the delay you see with these types, but a relay type photo cell doesn't have a delay and will remain off even if power or load is removed.

I learned this one the first time I changed a bad T-3 halogen lamp, thinking the photo cell had it off, as soon as it touched the contacts the lamp went on, and the napkin I was using burst into flames LOL, also this is the reason its not good to have a photo cell after the timer, if you have the timer turn on in the day light so will the lamp, until the heater heats up and turns it back off.

 

[hurk27]

I should add if you want to search for info on it, the thermo type is called an LDR type, Light dependent resistor.

 

[LarryFine]

I should add if you want to search for info on it, the thermo type is called an LDR type, Light dependent resistor.

I've never heard of a heater or bimetallic strip in a photocell. The LDR triggers the switching circuit. Is this a guess, or have you opened one?

Added: Your description sounds more like a lamp flasher or a standard-duty car turn-signal flasher.

The electronics takes a minute to charge up and set on some models, especially the slow-response ones that are resistant to lightning, car lights, etc.

 

[hurk27]

I've never heard of a heater or bimetallic strip in a photocell. The LDR triggers the switching circuit. Is this a guess, or have you opened one?
Added: Your description sounds more like a lamp flasher or a standard-duty car turn-signal flasher.

The electronics takes a minute to charge up and set on some models, especially the slow-response ones that are resistant to lightning, car lights, etc.

Oh you got to know I did lol,

it was a twist loc one for a dusk till dawn, and I also took apart a couple post light type which also used this same method, but the relay ones do use a small simple relay circuit, and I have even taken apart one that used a photo diode, it was a really small unit built into the fixture, as you moved your hand over the photo cell it slowly brought the light on from dim to bright, had to figure out why a CFL wouldn't last in it, it turned out this comming on dim was under voltaging the CFL, I put a 120 volt micro relay in them to just turn on the CFL when it got totally dark, home owners really wanted the lights and to use CFLs in them.

so go ahead and take apart one of those twist loc "slow to respond ones" and you will see what I mean.

 

[hurk27]

Heres a link to a thermal one:
scroll down to the spec's
Time delay is a bi-product of the thermal part of it.

 

[M. D.]

Wayne, would it not have been easier to use a different type of photo cell?

 

[jetlag]

thanks hurk27

thanks hurk27

I should add if you want to search for info on it, the thermo type is called an LDR type, Light dependent resistor.

Thanks for info I'll have to look into this ,I dont see how it is possible to put a photo cell and a heater in series with the load with out being severe voltage drop on load. A bimetal strip maybe, it is a heater itself. Either way two 90 watt spots dont need to dim down to 9 watt , I dont think you could see the light, so it is still not a problem.

 

[ELA]

I've never heard of a heater or bimetallic strip in a photocell. The LDR triggers the switching circuit. Is this a guess, or have you opened one?

Heres one open:
http://forums.mikeholt.com/showpost.php?p=1186111&postcount=18