Hi,
I had a photocell on a 35w sodium 110v that was working fine with an Intermatic K4221C. It is about 15 years old and was working find until I took it out.

I added to the line a 500 Watt (split 250 a side) low voltage transformer and installed low voltage lighting on one side only totaling 160 watts.

I re-connected the original photocell in the same position and now the photo cell stays on all the time.

I purchased a new Intermatic K4221C photo cell and I can force the shut off through an error mode (shining a light into the eye) . It will then come on at dusk like it is suppose to but will not shut off at anytime during the day. After speaking with Intermatic, I got a replacement but still the same problem.

The fact that it comes on at dusk I think is telling me it is hooked up right and that it is not by passing the photo cell.

Appreciate the help
Thanks

Phase shift or min load

1. Hook up a 7W or more light bulb in parallel with the primary of the new light. Report back.

Quote:

---

Originally Posted by KISS

Phase shift or min load

1. Hook up a 7W or more light bulb in parallel with the primary of the new light. Report back.

---

That light is brighter than the lights in "series".

Don't know what your trying to say. What I wanted you to do is to have your low voltage lighting connected as you have, but add a light like you had, but can be lower wattage, as a minimum load.

I don't think these photocells need a minimum load. I have tested these with no load, and they (switch) open and close reacting to light and no light, fine.

Good thought thou.

All I can think of is the PC does not see the sunlight, somehow causing it to stay closed.

The reason that Intermatic thought a defective unit, is that photocells fail closed.

Quote:

---

Originally Posted by KISS

Dont know what your trying to say. What I wanted you to do is to have your low voltage lighting connected as you have, but add a light like you had, but can be lower wattage, as a minimum load.

---

I added the light at the line source' not at the end of the string of lights already there. There are 8 lights all are 18w. I add another 18 watt to the primary and it was brighter than the other 8 lights.

Exactly what light are you adding to the primary?

Is the light added to primary rated for that voltage?

Quote:

---

Originally Posted by tkrussell

Exactly what light are you adding to the primary?

Is the light added to primary rated for that voltage?

---

Yes, it is 12v like all the rest.

Thanks

So if the primary is rated 12 volt, what is the voltage of the secondary?

The transformer is 110v that converts to 12v. Are you asking me to run the additional light off the primary of the 110v line before the transformer?

The transformer is 110v that converts to 12v. Are you asking me to run the additional light off the primary of the 110v line before the transformer?

I am not asking you to connect to anything.

Did you connect a 12 volt light to the 120 volt primary? Not recommended.

If so, of course it would be brighter. It should have exploded in your hand.

Perhaps we should start over again.

All your lighting works fine, the issue is your photocell does not work?

It worked fine with a 35 watt HPS?

Once you connect a 120 volt to 12 volt transformer with 12 volt lamps connected to the 12 volt side of the transformer, the PC stopped working properly?

It turns the lights on when it gets dark, but stays on in the sunlight in the morning?

I did not connect a 12v to to 120. I connected 12v bulb to 12v. Line
All light work. Both the 35w 110v sodium and the 8 18w 12v. And everything as you say is correct "All your lighting works fine, the issue is your photocell does not work?

It worked fine with a 35 watt HPS?

Once you connect a 120 volt to 12 volt transformer with 12 volt lamps connected to the 12 volt side of the transformer, the PC stopped working properly?

It turns the lights on when it gets dark, but stays on in the sunlight in the morning?"

All Correct.

Maybe there is something I am not understanding about where exactly the additional bulb should be connected to.
I assumed that when I connected the additional 18 watt 12v bulb to the 12v out of the power supply that is what you meant and that because it was getting a more direct feed and the other 8 bulbs that were in series, was the reason it was brighter.

Thanks again

I like this type:
NEW Lot 4 INTERMATIC Model K1122 PHOTO CONTROLS - eBay (item 350385533889 end time Sep-15-10 19:49:18 PDT)
They are instant on and off, don't have to cover and wait for switching.

Put a 120 V lamp connected across the 120 V side of the tansformer. Any 120 V lamp for testing only.

This is similar to the promblem where lamp dimmers don't work with motors, I think.

(edit): Changed simmers to dimmers

OK, try testing the photocell by disconnecting all load from the photocell and covering the PC and test for 120 volts across, the white and red. Uncover the PC should shut off the 120 volts across the white and red, covering should show 120 volts again across the white and red.

I want to be sure the PC works without a load.

Then re-apply the load and test again.

Could be the PC does not like the transformer for some reason.