Sensor to switch on garage lights

[JSM]

Hello Wizards,

I think this will be a difficult one. I had a sensor installed to switch the lights on in my garage when I drive in and to stay on for a few minutes. It was installed by a top class electrician. It worked great for a while but then the light began staying on. The electrician replaced the sensor and again it worked well for a while. However, it has now developed an intermittent fault whereby sometimes the lights stay on and other times they switch off as they should. Can anything else be tried apart from trying yet another new sensor?

Thanks in anticipation of your kind assistance.

 

[electronicsuk]

I expect your 'top class' electrician has fitted a PIR to control fluorescent lighting that is not rated to handle inductive loads.

Am I right?

 

[JSM]

Mathew,

Thanks very much for that. The truth is that I don't know but I think I know what you are getting at. The garage does have four big fluorescent lights. I have the leaflet for the sensor. Is there any information I could post from it which would help?

 

[electronicsuk]

Is there any information I could post from it which would help?

If you could find a manufacturer/part number and then find the instructions online, that would be very helpful. Short of that, look for anything specific regarding power/load ratings, especially if it specifically mentions that the sensor is for resistive loads only, not inductive.

 

[JSM]

Hi Mathew,

These any good? (Probably not.)

Viper Primo IR53 / 530C

Power 9-16 VDC, 12 Volt Typical

Current Drain 10mA, 12 VDC

 

[JohnD]

that says ist is a 12volt device, not mains

Is there a relay box somewhere?

 

[electronicsuk]

that says ist is a 12volt device, not mains

Is there a relay box somewhere?

Must be, managed to find this from the installation manual, and it looks to be a typical 12v PIR sensor for an alarm system. Nothing wrong with that as it clearly must be switching a contactor or relay somewhere, but that could still cause problems if the coil load is too large or the electrician has omitted to include back-EMF protection in the form of a diode in reverse parallel with the coil. The contacts in that PIR are only rated to 200mA @ 30v max.

 

[JSM]

Hi JohnD,

I'm not sure what a relay box is but there is a fuse box in the garage. Also, the electrcity meter is in the garage, the garage door is electrically operated and there are a number of electrical sockets. Any use?

 

[electronicsuk]

Hi JohnD,

I'm not sure what a relay box is but there is a fuse box in the garage. Also, the electrcity meter is in the garage, the garage door is electrically operated and there are a number of electrical sockets. Any use?

Hmm, are the fluorescent lights operated by the garage door opener which is also linked with the PIR sensor, or solely by the PIR? If it's the former, it might explain the use of a 12v PIR.

 

[JSM]

Hi Mathew,

No, the garage door has no connection with the sensor. It is quite independent.

 

[electronicsuk]

Hi Mathew,

No, the garage door has no connection with the sensor. It is quite independent.

Then I'd say your best bet right now is to try and trace back the cable from the sensor. As John mentioned, there must be a box with a relay and transformer in it somewhere to switch the lighting load and provide the 12v supply. Either that, or the sensor is wired as part of the alarm system with the lamps being switch by an auxiliary output on the panel.

 

[JSM]

Thanks very much for your advice guys; it is appreciated. I can see it is complicated enough to warrant getting my electrcian back. He is a top tradesman so hopefully with two different sensors experiencing problems he will give it a thorough examination.

Many thanks again.