Coil inrush and photocells

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nizak

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I have a lighting contractor that is being controlled by a 120v photocell.

The coil inrush is 180VA the holding is considerably less.

I am having difficulty in finding a photocell that will last more than a few months.

The rating is 8.3 A

Is it the 1.5A inrush that would be causing the failure?

The same photocell is working fine throughout the rest of the property controlling loads near its rating without failure.

The other applications are 120V lighting loads that are wired without a coil and contractor.

Thanks
 
Use a different brand of photocell?

This one must not have very good quality contacts?

Low level (low volts, low amps, both) switching sometimes needs higher quality contacts but 120 volts 180 VA shouldn't have much trouble with most switch contacts that are out there.

ADD: Another option is maybe to put more load on the switch, though that decreases overall efficiency.
 
Will try another brand.

First one that failed was a Woods brand. Got it from property maintenance person onsite.

Second one I installed was an Intermatic. Neither lasted more than a few months.

Thanks for the replies.
 
Can't find any literature on the woods. Maybe solid state not like the old intermatic.
 
Do know that the Big Box place carries Woods products.

The Intermatic I furnished came from the Wholesale house.
 
nizak said:
The rating is 8.3 A

Is it the 1.5A inrush that would be causing the failure?

The same photocell is working fine throughout the rest of the property controlling loads near its rating without failure.
Click to expand...


Why not use an 1800 Watt photo cell?

The real cost of failure is the cost to replace. The cost of a larger wattage photo cell is not that much.

I never like to load a photo cell or a dimmer even close to it's rating. They last longer if you don't.
 
It actually is 1800 watt rated for tungsten.

Lesser rating for ballast.

I indicated the ballast rating which was less.

My bad.
 
Even at the lesser rated amperage it's not even close to the draw that I'm dealing with.

Will try another Intermatic and see what happens
 
kwired said:
Use a different brand of photocell?

This one must not have very good quality contacts?

Low level (low volts, low amps, both) switching sometimes needs higher quality contacts but 120 volts 180 VA shouldn't have much trouble with most switch contacts that are out there.

ADD: Another option is maybe to put more load on the switch, though that decreases overall efficiency.
Click to expand...

Do photocell switching units use mechanical contacts? I would have thought they used triac solid state switching.
 
Looking at the intermatic site they have two versions of the photocell. One the old cadmium sulfide type light sensor and mechanical switch, then the new solid state electronic version.
 
If there is no snubber circuit across the relay coil, possibly the failure is caused by the repeated voltage spikes when the photocell opens. The relay coil is a good inductor for modelling what happens when the photocell opens.
 
Is the one that fails installed so the cell is facing direct sun at some time in the day? Many will quickly fail if you do that.
 
In 40 years I never had to place a snubber on a lighting relay switched by a photocell.

No reason to re-invent the wheel here. The manufacture should place in its spec what it will no longer do.
 
Sierrasparky said:
In 40 years I never had to place a snubber on a lighting relay switched by a photocell.

No reason to re-invent the wheel here. The manufacture should place in its spec what it will no longer do.
Click to expand...

Aside: My neighbor has an outside light controlled by a photocell, but when it was first installed, the cell could "see" the light from the lamp. All night long it would cycle off and on with about a 1 second period.
 
ggunn said:
Aside: My neighbor has an outside light controlled by a photocell, but when it was first installed, the cell could "see" the light from the lamp. All night long it would cycle off and on with about a 1 second period.
Click to expand...

Sounds like a problem with the installation not the photocell.
 
ggunn said:
Do photocell switching units use mechanical contacts? I would have thought they used triac solid state switching.
Click to expand...
Sounds like there must be some solid state switching units out there, all I have ever seen is mechanical contacts. Majority of which the photo cell is a power source for a small heat strip and heats a bi-metal strip which actuates the contact. Contact on those is normally closed, when cell receives light it heats up the bi-metal and opens the circuit after a short delay period.

Question for OP is the load failing to turn on or failing to turn off? If your unit is like the one I described, failure to turn on is likely an output contact failure. Failure to turn off is likely failure of photo sensor itself or the heater it drives, or possibly welded contact.
 
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