# photocell failure question



## erics37 (May 7, 2009)

Just a quick question, not really inspired by anything in particular. More of a general observation.

I've done plenty of service calls troubleshooting exterior lights. Most of the photocells around here are various styles made by Intermatic (like this one):










Sometimes I'll get a call where they say their exterior lights won't turn on. Go down, find the photocell, wire nut the line and load wires together, and all the lights come on. Photocell took a crap.

Other times I'll get a call where they say their exterior lights won't turn *off*. Go down, find the photocell, disconnect it, lights turn off. Replace the photocell with a new one and simulate night/day and the lights turn on and off accordingly.

My question is, what makes photocells fail open or closed in differing circumstances?


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## kbsparky (Sep 20, 2007)

Can you say...

JUNK?

Probably power surges, combined with the increased use of micro-electronics makes `em vulnerable to premature failure.


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## erics37 (May 7, 2009)

kbsparky said:


> Can you say...
> 
> JUNK?
> 
> Probably power surges, combined with the increased use of micro-electronics makes `em vulnerable to premature failure.


Well for sure! I understand all that.

But why do they sometimes fail open vs. fail closed?


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## MDShunk (Jan 7, 2007)

erics37 said:


> My question is, what makes photocells fail open or closed in differing circumstances?


Interesting question, but one that does not require an answer, in my opinion. 

I've seen them with lenses that are so fogged up with dew and yellowed from UV that they thought it was night all the time.


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## mdfriday (May 14, 2007)

erics37 said:


> Just a quick question, not really inspired by anything in particular. More of a general observation.
> 
> I've done plenty of service calls troubleshooting exterior lights. Most of the photocells around here are various styles made by Intermatic (like this one):
> 
> ...


I have found, the more of a load running through them the faster they fail.

I like to use a contactor and have no load running through the cell.


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## erics37 (May 7, 2009)

MDShunk said:


> Interesting question, but one that does not require an answer, in my opinion.
> 
> I've seen them with lenses that are so fogged up with dew and yellowed from UV that they thought it was night all the time.


Yeah you're probably right. Given that they have electronics and stuff in them, it's kind of in that realm of electrical work where I just say "Yup, the whole thing's shot."


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## erics37 (May 7, 2009)

mdfriday said:


> I have found, the more of a load running through them the faster they fail.
> 
> I like to use a contactor and have no load running through the cell.


I prefer that as well but in some applications it's not really practical. The one I replaced this morning was only running a contactor coil but it failed closed. The contactor never opened so the lights were on 24/7.


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## bobelectric (Feb 24, 2007)

I always see them dying with the lights on. I like the swival mounts.


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## kaboler (Dec 1, 2010)

They tell me to never face a photocell facing the morning sun. The ones I install are always looking north, or at a wall.

They fail open too sometimes? Cool. I assume it's just a relay. Failing open for car relays sometimes means water gets inside. Condensation?


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## erics37 (May 7, 2009)

kaboler said:


> They fail open too sometimes? Cool. I assume it's just a relay. Failing open for car relays sometimes means water gets inside. Condensation?


There aren't any electromechanical relays in the typical cheap-o photocells I usually get. Just a bunch of semiconductive crap.

Water infiltration and UV damage and possibly heat, I believe, are the primary means of failure for these things.


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## frenchelectrican (Mar 15, 2007)

The other thing useally kill the photocells is surge { a strong one will do it } 

Some of the photocell they will stay on if failed and some will stay off in failed mode.

That part I have to look up the catalog book to make sure due just change one digit on the model number it will go either way.

And the FC level to kick on and off.

If you have a twistlock photocell caps make sure you get a shorting cap many time it will come handy more than just once so I can elemated the issue with it.

Merci.
Marc


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## Cletis (Aug 20, 2010)

*Quality*

You would think someone could make one that could withstand UV and Water Infiltration. Load...not sure. 

Sick and Tired of Failing Photocell's that I install. 


Great for lot's service call's though....easy money

Anyone know any good higher quality ones ??


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## Mr Rewire (Jan 15, 2011)

Cletis said:


> You would think someone could make one that could withstand UV and Water Infiltration. Load...not sure.
> 
> Sick and Tired of Failing Photocell's that I install.
> 
> ...


 intermatic makes a 4100W heavy duty it sells for about $25.00


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## Cletis (Aug 20, 2010)

*Nice*

That ain't squat. I'm gonna go buy 10 of them tomorrow! Sick of driving to sites that I've put them in a year ago


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## Brechi98 (Jan 26, 2010)

erics37 said:


> I prefer that as well but in some applications it's not really practical. The one I replaced this morning was only running a contactor coil but it failed closed. The contactor never opened so the lights were on 24/7.



+1:thumbsup:


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## Mr Rewire (Jan 15, 2011)

Cletis said:


> That ain't squat. I'm gonna go buy 10 of them tomorrow! Sick of driving to sites that I've put them in a year ago


 I stoped installing the 1800W cells I have saved alot of cash not doing return trips.


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## GEORGE D (Apr 2, 2009)

Does anyone know why most pc's take soooooooo long to come on when testing them? If I'm not mistaking, low voltage pc's react much faster, like on electronic stuff , toys etc..


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## erics37 (May 7, 2009)

frenchelectrican said:


> That part I have to look up the catalog book to make sure due just change one digit on the model number it will go either way.


So you're saying that some photocells intentionally fail open or closed? That's interesting... I didn't realize that! Hmm, I wonder if the standard crap Intermatic photocells are like that. I'm gonna look it up.



GEORGE D said:


> Does anyone know why most pc's take soooooooo long to come on when testing them? If I'm not mistaking, low voltage pc's react much faster, like on electronic stuff , toys etc..


They're designed with a delay. If they weren't the lights they controlled would shut off every time a car drove by at night with its headlights on.


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## Fractured (Feb 15, 2011)

We have had a lot of good luck with the Wattstopper ones.


















Installed one today!!


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## miller_elex (Jan 25, 2008)

That's why I put the photocell ontop of a C-condulet for quick swappage.

Well, I guess you got to put it ontop of something anyways, bell box, etc.


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## erics37 (May 7, 2009)

miller_elex said:


> That's why I put the photocell ontop of a C-condulet for quick swappage.
> 
> Well, I guess you got to put it ontop of something anyways, bell box, etc.


Yeah I just wire nut my photocells to the building wiring and let it hang there :laughing:


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## Malaking_TT (Dec 17, 2010)

erics37 said:


> Yeah I just wire nut my photocells to the building wiring and let it hang there :laughing:



Seems like a lot of people waste a lot of time putting them on the roof. I go out the nearest wall and stick it on a bell box about 2' high. (When it's my choice that is)


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## erics37 (May 7, 2009)

Malaking_TT said:


> Seems like a lot of people waste a lot of time putting them on the roof. I go out the nearest wall and stick it on a bell box about 2' high. (When it's my choice that is)


There's a couple of government subsidized apartment complexes around here with photocells a couple feet above the ground. They call us once every couple of months to go replace them because the juvenile delinquents living there go and kick them off and stuff.

I keep offering to extend them up to an out-of-reach height but they refuse. "Well they'll just rip the conduit off the wall then."


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## Malaking_TT (Dec 17, 2010)

erics37 said:


> There's a couple of government subsidized apartment complexes around here with photocells a couple feet above the ground. They call us once every couple of months to go replace them because the juvenile delinquents living there go and kick them off and stuff.
> 
> I keep offering to extend them up to an out-of-reach height but they refuse. "Well they'll just rip the conduit off the wall then."


I bet they got installed fast. 

When doing bidder design work do things that will add to your future service calls.


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## B4T (Feb 10, 2009)

I have always used the "pencil" type.. seems to last the longest for me.. 

Like this one, but minus the modular plug on the end..


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## frenchelectrican (Mar 15, 2007)

erics37 said:


> So you're saying that some photocells intentionally fail open or closed? That's interesting... I didn't realize that! Hmm, I wonder if the standard crap Intermatic photocells are like that. I'm gonna look it up.


Most intermatic photocell failure most case useally fail in open mode { off } but I know couple verison they will fail in close mode { stuck on } the close mode useally result of surge which I have see it but near by lighting strikes useally kill them to open mode and they are done for it unless you have built in lighting arrester in the photocell { that part I have to verify with the catalog to make sure it have it }




> They're designed with a delay. If they weren't the lights they controlled would shut off every time a car drove by at night with its headlights on.


Most case they will have delay off but few will have delay on as well depending on model but even with delay off Photocells what set them very fast off is the aircraft headlight or search light they will trip it pretty fast I have see it quite few time { due I fly the helicopter from time to time } 

Merci.
Marc


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## hardworkingstiff (Jan 22, 2007)

In the 70's and 80's, every photo cell I serviced had failed in the on position. I was told the photo cell was always on and the sun caused it to open. I was told the photo cell failed to the on position so you would know the photo cell was defective.

About 10 (or so) years ago I noticed an occasional failed off photo cell. It was weird to me due to my experience. I never did research the issue to find out why.


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## Foestauf (Jan 5, 2011)

Most premature photocell failure comes from improper installation. If you place the eye in direct sunlight it will not last long. 
Install facing north and use the blinder if it installed out in open. 
People saying the intermatic failing within a warranty period is improper installation, to include upside down, nearby artificial light causing frequent cycling, or overload condition.


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## Fractured (Feb 15, 2011)

Foestauf said:


> Most premature photocell failure comes from improper installation. If you place the eye in direct sunlight it will not last long.
> Install facing north and use the blinder if it installed out in open.
> People saying the intermatic failing within a warranty period is improper installation, to include upside down, nearby artificial light causing frequent cycling, or overload condition.


I forgot the whole "north orientation" rule (if you live in the northern hemisphere)


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## crazyboy (Nov 8, 2008)

Have had good luck with TORK.


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## DoCJohnny (Feb 16, 2011)

Anyone have issues when adding a switch in parallel to the photocell (so the lights could be turned on manually)? This would "back feed" the photocell, would that damage it or cause premature failure.


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## erics37 (May 7, 2009)

frenchelectrican said:


> ...{ due I fly the helicopter from time to time }
> ...


Is this you piloting this helicopter?? (Best movie scene ever, by the way)








DoCJohnny said:


> Anyone have issues when adding a switch in parallel to the photocell (so the lights could be turned on manually)? This would "back feed" the photocell, would that damage it or cause premature failure.


I've done that before. I don't think it causes a problem.


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## frenchelectrican (Mar 15, 2007)

Eric .,

I flew on Bell Helicopters from time to time but I do run the smaller one { piston powered unit } they are not too bad. 

I know there is other electrician in other fourm he is helicoptor polit as well he run little larger than Bell class { size } I have to ask him what other aircrafts he flew. { He is from New Zenland area }

Merci.
Marc


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## frenchelectrican (Mar 15, 2007)

DoCJohnny said:


> Anyone have issues when adding a switch in parallel to the photocell (so the lights could be turned on manually)? This would "back feed" the photocell, would that damage it or cause premature failure.


 
That useally not a issue it simair to the H-0-A switch on starter bucket it the same way so in few large complex I just hit the H-O-A switch to do the task { few case you may find a three way toggle switch function the same way.,,, }

That is pretty common item I have see in quite few place and however let me add this some Photocell may have a time clock on it as well to set at X time on and Z time off.


Merci.
Marc


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