Ask The Trades - PIR HELP

ronb

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PIR HELP
Mar 5^th, 2010, 7:48pm

Hi iv'e installed 11 led lights into the side of my stair case and id like to install an pir into the ceiling over the stair case. Any way the question is
i need some advice on what type of pir i need because the led lighting plug in transformer is a = 12vac max 10va and the led's are 0.3w each, so 11 led's x 0.3 = 3.3 v
is this voltage to low to activate an PIR
ideally the pir needs a wide angle to pick up movement from the top and bottom of the stair case
thanks in advance Ron

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Lectrician Administrator Offline Ask The Trades Posts: 7446 Karma: 12 Braunton, North Devon United Kingdom Gender: Trade: Electrician Mood:	Re: PIR HELP Reply #1 - Mar 5^th, 2010, 8:09pm You would use a main voltage PIR detector to switch the mains voltage side of the transformer. Search for occupancy sensors.
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ronb Junior Member Offline I love YaBB 1G - SP1! Posts: 20 Karma: 0	Re: PIR HELP Reply #2 - Mar 9^th, 2010, 2:09pm Thanks for the reply does that meen that its erelevent what voltage / wattage its activating. can you recommend a wall mounted pir ?
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CWatters

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Re: PIR HELP
Reply #3 - Mar 9^th, 2010, 11:58pm

Almost all PIR are designed to switch high power 240V lights so they should cope fine switching the mains supply to a few low power LEDs. Suppose your LEDs add up to 10Watts. Any PIR rated for more than 10 Watts should work (that will be virtually all of them).

However note that there might be a problem with some types of PIR due to your load being too small. Hard to explain but if possible go for a PIR that needs a "permanant live" connection rather than one intended to "power itself through the load".

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« Last Edit: Mar 9^th, 2010, 11:58pm by CWatters »

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sparxxxx Full Member Offline Posts: 406 Karma: 0	Re: PIR HELP Reply #4 - Mar 10^th, 2010, 3:03pm Its going to be difficult to get a PIR to work on a standard stair case. To operate a PIR you need to break two of the 'beams' this is difficult to achieve if the PIR is pointed straight up or down the stairs. It really needs to be at right angles to the stairs.
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Zambezi Trade Offline Use my advice at your own risk! Posts: 1773 Karma: 4 Gender: Trade: Electrician Mood:	Re: PIR HELP Reply #5 - Mar 11^th, 2010, 8:15am I normally fit the PIRs in the ceiling. If you want to fit them to the wall then you will probably need one at the top and the bottom of the stairs.
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