Nothing to do with cars question

Deleted account DD · 17-01-2010, 19:56

Hopefully therell be someone on the forum who knows this one

PIR sensors on burglar alarms, are they normally open circuit and close on activation or are they normally closed circuit and open on activation

I need to rplace a couple in our house, its that long since I've had to buy any I cant remember which way round and I know you can get both

zippy656 · 17-01-2010, 20:08

PIR thats waht i need....

turn the lights off the kids keep leaving ON!!

um could be either... depends on use

Deleted account DD · 17-01-2010, 20:16

Helpful answer mate

Keep watching a decent one may appear

Deleted account DD · 17-01-2010, 20:21

Just been looking via google and my monies on normally closed because most systems tell you to wire multiple pirs in series

(RIP) PLANK · 18-01-2010, 18:52

cant you take one of your old ones down and test it?

I beleive thay are normaly closed, as in this case cutting the wires would cause an open circuit and would set the alarm off, so it makes sense.

Though it has been a long time since i have messed with alarm systems!

rayf3262 · 18-01-2010, 19:12

The majority of the ALARM pir's are normally closed (the idea being if you cut the wires it creates an alarm condition) some units have a small reed relay that has changeover contacts offering both NC and NO options.
Ray

Deleted account DD · 18-01-2010, 20:00

Thanks folks

17-01-2010, 19:56	#1
Deleted account DD Senior Member Join Date: Sep 2008 Posts: 4,705	Nothing to do with cars question Hopefully therell be someone on the forum who knows this one PIR sensors on burglar alarms, are they normally open circuit and close on activation or are they normally closed circuit and open on activation I need to rplace a couple in our house, its that long since I've had to buy any I cant remember which way round and I know you can get both

17-01-2010, 20:08	#2
zippy656 Senior Member Join Date: Aug 2008 Location: Devizes Wiltshire Vehicle: Nissan Note Ntec 1.5 Posts: 14,138	PIR thats waht i need.... turn the lights off the kids keep leaving ON!! um could be either... depends on use

17-01-2010, 20:16	#3
Deleted account DD Senior Member Join Date: Sep 2008 Posts: 4,705	Helpful answer mate Keep watching a decent one may appear

17-01-2010, 20:21	#4
Deleted account DD Senior Member Join Date: Sep 2008 Posts: 4,705	Just been looking via google and my monies on normally closed because most systems tell you to wire multiple pirs in series

18-01-2010, 18:52	#5
(RIP) PLANK Senior Member Join Date: Mar 2006 Location: Central England, in the Heart of the Black Country Vehicle: T2 2004 TDI SE LWB Posts: 7,740	cant you take one of your old ones down and test it? I beleive thay are normaly closed, as in this case cutting the wires would cause an open circuit and would set the alarm off, so it makes sense. Though it has been a long time since i have messed with alarm systems!

18-01-2010, 19:12	#6
rayf3262 Senior Member Join Date: Nov 2009 Location: Norfolk, Poringland NR14 Vehicle: Terrano 3.0 SVE 2002 Posts: 1,549	The majority of the ALARM pir's are normally closed (the idea being if you cut the wires it creates an alarm condition) some units have a small reed relay that has changeover contacts offering both NC and NO options. Ray

18-01-2010, 20:00	#7
Deleted account DD Senior Member Join Date: Sep 2008 Posts: 4,705	Thanks folks