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Internal pir activates when there is no motion present.

I have just had an internal PIR sensor fitted in one of the rooms to turn the light on. However the light keeps turning on when there is no one in the room. I have checked for spiders and cobwebs but I can't get my head around it.
I don't know the make of the sensor, however it has two settings one for time and the other for light.

Does anyone have any ideas?

3 Answers from MyBuilder Electricians

Best Answer

There must be a heat source that triggers the PIR. It can be anything from sun rays to radiator.This usually happens with low quality PIR's.

Hope that helps.



Answered 28th Apr 2015

One of the switches will be for the sensitivity of the device so try reducing this to a minimum setting. If that does not work you have a defective device.

It is most unlikely, even on the highest setting, that a spider would trigger it, so it is probably defective and you have every right to call the installer back to put it right even if it is not his fault.

I am sure any electrician would understand this and would be happy to return unless you supplied the equipment, in which case you must expect to accept his charge.


Answered 28th Apr 2015

Most likely picking up on warm air circulating from a radiator or other heat source. Would recommend upgrading to Microwave sensor as these are not affected by spurious air movements.


Answered 28th Apr 2015

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