Problem with outside light.

turnitround

9 months ago we had a new security light put up at the back of our house. One of those with a sensor which picked up on anyone walking into the garden or going out of the back doors.

It worked perfectly and floodlit the back garden when it cme on.

The last couple of weeks I have noticed it is not working properly.  My son first noticed that it did not come on, he gets home from work at 1am so its pitch black then.
The thing is that it will work perfectly for one night lighting up when we let the dog out or son comes in. The next night it will work when we let the dog out before bed but not 2 hours later when son gets home. 
Then it may not work at all for 2 nights but then magically work the following night. 

Does anyone have any idea what the problem may be. Cant be the bulb as it works intermittently, the sensor has not moved from its position.
Could it be a fault on the wiring, perhaps something loose. 

Robin9

A couple of things - is there water in the fitting ? - is the sensor dirty or tilted?

turnitround

Robin9 said:

A couple of things - is there water in the fitting ? - is the sensor dirty or tilted?

Thanks for the reply. No there is no water getting in the fitting and the sensor is fixed quite tightly in the same place and does not move in the wind or anything like that.
You can literally walk out of the door at 10pm and it will light up when the sensor picks you up at the top of the garden steps then go to exactly the same place an hour later and it does not come on. 

ThisIsWeird

I suspect nothing more complex than a less-than-decent quality LED fitting that's on the way out.

(You are now going to tell me it cost an arm...)

turnitround

ThisIsWeird said:

I suspect nothing more complex than a less-than-decent quality LED fitting that's on the way out.

(You are now going to tell me it cost an arm...)

It is less than a year old and  was put in as part of a lot of work they were doing to the electrics as they were ancient when we moved in. Everything else they did has been fine. The annoying thing is that there was a perfectly good one on the wall, old and ugly but working. When we got the electricians in it was discovered that the light had been taken off a box in the loft and was not done correctly so they were replacing the wiring to it. 
Due to lack of communication between the owner of the business and the guy doing the work I came home to find they had replaced the light fitting as well as the wiring which was not needed as the old one was fine.  
They had thrown the one they had taken down into the skip and broken it so it could not be put back. However they agreed not to charge me for the light as it had not needed to be replaced.
Now I have a light which looks very nice and a lot more compact than the old ugly one but is not working properly.

EssexExile

I've found over the years that with these automatic lights you have to keep changing them until you get one that works reliably, then stick with it!

ThisIsWeird

turnitround said:

ThisIsWeird said:

I suspect nothing more complex than a less-than-decent quality LED fitting that's on the way out.

(You are now going to tell me it cost an arm...)

It is less than a year old and  was put in as part of a lot of work they were doing to the electrics as they were ancient when we moved in. Everything else they did has been fine. The annoying thing is that there was a perfectly good one on the wall, old and ugly but working. When we got the electricians in it was discovered that the light had been taken off a box in the loft and was not done correctly so they were replacing the wiring to it. 
Due to lack of communication between the owner of the business and the guy doing the work I came home to find they had replaced the light fitting as well as the wiring which was not needed as the old one was fine.  
They had thrown the one they had taken down into the skip and broken it so it could not be put back. However they agreed not to charge me for the light as it had not needed to be replaced.
Now I have a light which looks very nice and a lot more compact than the old one but is not working properly.

I replaced some ugly & ancient PIR halogen security lights that came with the house a few years ago. I fitted petite LED units, assuming they'd last 'forever'. Despite actually rarely being used, they failed within a few months, as did a replacement. Carp. 
Intermittent issues like yours are the worst kind to ID, but I'd lay odds on it being the light fitting itself rather than the wiring.
I even fitted a fancy 'designer' wrought iron LED lamp on our recent extension, again rarely turned on. After a few months the LED reduced to a weak glimmer. I pulled out the guts - a trannie and two LED strips - which annoyingly began to work when wired up afterwards - and mounted a couple of SES holders instead, to take normal LED 'bulbs'.
There's a lot of very poor units out there.

ThisIsWeird

In theory, of course, it's all still under warranty
No harm in asking the sparky to pop in whenever they are passing?