More lighting oddities

[ProDave]

Here is the setup.  At a pub I do various maintenance jobs.  Outside lights, one pub name sign, two Tenants "T" signs and 2 LED spotlights, all switched from a dusk to dawn sensor.  One of these.

It has been working for years.  Until I had to change one of the LED spotlights, one mounted just above the daylight sensor.

Next day I was called. "The lights are staying on all day"

I went and looked.  Unplugged the sensor expecting the relay to be stuck.  No it was okay. plugged the sensor back in, it worked fine switching on and off okay.  I pondered if these things had an overide facility, you know like PIR lights used to interrupt the power momentarily and they then stay on?

2 days later, phone call "the lights are staying on all day"  So I order a new sensor thinking this one is goosed.

Just back from trying to fit it.  New sensor plugged in. Cover it, wait for it to turn on, uncover it. Does not turn off.  WTGrape?  Just could not get the new sensor to turn off.

Out of desparation, I put the old one back and it worked fine the 3 times I tried it.

But why do I get the feeling the phone will ring tomorrow?

Next step will be different make of replacement LED spotlight.  But why does something so simpe end up with so much buggering about and time wasted?

 

[Sharpend]

Quick research without reading too much so don’t know if significant? 
https://www.google.co.uk/search?

 

[kerching]

Is it a standard photocell?

we had some weird Royce Thomson ones back in the day and they had a built in timer that was factory set

took ,three or four days to settle down after being energised

 

[ProDave]

As expected, this problem came back a couple of days later.  It has now been solved:

I bought a new, deliberately different make, LED spotlight.  I tested the new daylight sensor and the new light on the bench several times and it switched properly.  I then went and installed them and tested it's operation several times and it worked.

I then bought the old LED floodlight and the old sensor home.

I first tested the sensor with a CFL lamp.  It switched correctly several times.

I then connected the old LED light to the sensor.  On the second switching, it remained on when the sensor was put back into daylight (it should have switched off)  Power cycling did not fix it, it remained stuck on.  but a sharp tap on the sensor switched it off.  It worked twice more correctly before getting stuck on again.

My conclusion:  This rogue LED spotlight (Pro elec from CPC if you are looking for what to avoid) has a very high inrush current as is actually welding the relay contact as it turns on, hence a physical blow to the sensor being required to unstick it.

And it's not just a dud / worn out sensor, remember it did that when I just tried the new sensor in situ with that old rogue spotlight.

 

[Evans Electric]

 Well sorted Dave ,    so another gremlin caused by modern solid state switching  paired up with  certain LED fittings  .   Thanks for follow up .

All sent to cost us more of our time & money .  

 

[ProDave]

Yep that's one job where I spent way more time than the job paid.

 

[Andy™]

fitted loads of LEDs to those photocells. never had an issue yet