PIR Detectors: How To Do A PIR-fect Job

PIR Detectors: How To Do A PIR-fect Job

With PIR detectors offering big business these days, Timeguard’s Andy Douglas shares his advice to ensure your profits aren’t eaten away by having to return to put a job right.

Assuming you’ve bought good branded quality PIR detectors, any problems that arise after installation are most likely to arise from having chosen the wrong spec or through an incorrect set-up.

Here are a few pointers to help you get it right:

What type of lights and what load?

For LED lighting, make sure the PIR detector is specifically tested with and rated for LED loads. The specification on the box should clearly state what LED loading is acceptable.

The huge difference between ratings for the same PIR detector for halogen and LED still comes as quite a surprise to some people. For instance, our new mini linkable PIR, is rated for 1,000W max (halogen) and 250W max (LED).

That’s because the LED rating has to allow for the strong inrush current on switching, not the subsequent low running current.

Will there be lots of luminaries?

If you want to control several luminaires, with a total LED ratings getting near the limit of the PIR’s specification, do think things through carefully. For instance, our Timeguard SLW360deg detectors have a maximum LED load of 150W, but we ‘only’ rate them for a maximum of 10 separate LED 10W lamps (100W).

Yet we’re happy to rate, and guarantee, it for 5x sets of LED lamps above 10W, right up to the 150W limit.

This is because, due to their physical size, lower wattage LED lamps (GU10 type lamps) commonly have very simple circuitry with surge protection and power factor correction omitted, which puts a massive strain on whatever is switching/controlling them.

Looking for a big rating might also mean that a large area is to be lit, so perhaps a single PIR detector will not be able to give the comprehensive detection field needed.

Would multiple PIRs instead be better?

Maybe it would be easier – and less expensive – to be able to link a master and several slaves together? When these come fitted with cables and standard RJ11 plugs and sockets, like our linkable PIRs, huge amounts of time can be saved on both installation and setup.

Where’s it going?

Technology has inevitably moved on and most quality PIRs now offer more sensitive presence detection so they can tell the difference between an empty room and a quiet office.

If they do specifically state that they offer presence detection, it is likely that the design is newer and all of the componentry is bang up-to-date.

As a general rule, a ceiling height of 2.5m will give optimum coverage, nearest to the diagrams in the manufacturer’s instructions. Remember that highly reflective surfaces and heat sources like extractor fans nearby can interfere with sensitivity.

It may also be useful to have an easy way of masking part of the detector to avoid nuisance switching.

For more information about the range of PIR detectors from Timeguard visit: www.timeguard.com

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