Choosing PIRs

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Don’t set yourself up for PIR failure, says Timeguard

Timeguard ceiling mounted PIR detector“What’s the cheapest PIR you’ve got, mate”. That was overheard at a wholesale counter within earshot of a visiting Timeguard representative who only stopped spluttering when he heard the ‘right’ reply from the man behind the counter. “What’s it going to be used for?”. Phew!

PIR detectors are not all the same, but they are typically mounted on ceilings or high on walls – places that are hard to get to if they fail or need constant readjustments.

Branded quality is always the safest option, but even the you need to make sure you get the specification right. So here are just 3 key questions to help them to help you get the balance between price and performance right:

  1. What type of lights and what load?

These days the job will almost always be LED lighting, so make sure they know to pick a PIR detector that is specifically tested with and rated for LED loads.

We’ve been saying for years how important this is. LED lights have a strong inrush current and it is that which the PIR should be rated for, not the subsequent low running current.  You shouldn’t need to do the maths, the specification should already state what LED loading is acceptable – if not steer clear.  We think it’s always wise to add at least 10% for good measure).

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 1000W max. halogen and 250W max. LED.

  1. Is it going to be a straightforward stand-alone automatic switch?

If you are looking at very high LED ratings, for a single PIR to switch several lights, double check the spec. For instance, our top-selling 360o ceiling mounted detector has a maximum LED load of 150W, but we rate it for a maximum of 10 separate LED 10W lamps (100W). Yet we are happy to rate – and guarantee – it for 5 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, this puts a massive strain on whatever is switching/controlling them.

Looking for a big rating might also mean that a big 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 be better?

Timeguard mini PIR and plig in slave_lowresMaybe 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, huge amounts of time can be saved on both installation and set up.  The ingenious Timeguard linkable concept makes wiring simple because up to 5 slaves are linked by pre-fitted plug-in wires that stay hidden behind a suspended ceiling. Simples.

  1. Where’s it going?

Will the detector be surface mounted on a wall, flush mounted in a standard ceiling aperture, or would a corner bracket help? How important are looks to the end user?

Do you need the option to mask part of the detector?  What’s the room being used for and do they really need presence detection around desks or areas where people sit fairly still? If it’s going to be within reach of passers by and ‘keen’ building occupants, do you need to ensure that the controls are tamper proof?

Timeguard tamper proof PIR

Indoors or out? Check the IP rating. If outdoors, might it be easier to replace old and corroded lights with an all-in-one floodlight with integral PIR detector designed to withstand the British climate. Check out the corrosion-free Timeguard coastal range.

All this might give you cause to rethink. Branded quality is still the best assurance of fit-and forget  quality. No-one wants to have to go back and change a failed PIR detector.

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