Connecting one light to two PIR detectors?

Connecting one light to two PIR detectors?

Author
Discussion

Dr Mike Oxgreen

Original Poster:

4,101 posts

164 months

Saturday 3rd January 2015
quotequote all
I am pondering fitting a light to illuminate down one side of the house, and would like to use a dusk-to-dawn PIR detector. As far as possible I'd like the PIR detector to cover the whole side of the house, so that the light comes on when you approach from either end.

The problem is that half way along this side of the house is the boiler flue, which sends its exhaust out just above head height. Obviously this will cause a PIR detector to trigger erroneously.

Is it possible to power one light from two PIR detectors? I could mount a PIR detector on each side of the flue, pointing away from it, and this would cover most of the area I want. Would drifting gases still cause a problem?

Can I wire the light in parallel to the outputs of both PIRs, so that it would light up in response to either PIR?

The only problem I can think of is that when just one PIR triggers, the switched output on the other PIR would become live. Would this cause that PIR to malfunction in any way?

moles

1,794 posts

243 months

Saturday 3rd January 2015
quotequote all
is fine to wire 2 pir's i have done this to one light with a pair either side of my shed. as long as they are pointing away from the flue i would imagine they will be ok.

B17NNS

18,506 posts

246 months

Saturday 3rd January 2015
quotequote all
Yes it can be done. A spark did it for me at my old place and incorporated a switched override as well. He explained how he'd done it as I smiled and nodded (I have a rudimentary knowledge of electrics). He might just as well have been speaking Urdu laugh

Dr Mike Oxgreen

Original Poster:

4,101 posts

164 months

Saturday 3rd January 2015
quotequote all
Brilliant - thanks folks! I couldn't think of any reason why not, but it does no harm to ask.

R1 Indy

4,381 posts

182 months

Saturday 3rd January 2015
quotequote all
Yes you can do this no problems.

Here is a very basic diagram I made someone a few years ago


B17NNS

18,506 posts

246 months

Saturday 3rd January 2015
quotequote all
R1 Indy said:
Like I said. Urdu.

DrDoofenshmirtz

15,184 posts

199 months

Saturday 3rd January 2015
quotequote all
All you do is link all the switched sides of the PIR's together.

So, inside the PIR wiring blocks you will have:
1= Earth
2= Neutral
3= Live mains feed
4= Switched output from the PIR sensor to the lamp.

Link all the 4's together.

dirty_dog

676 posts

175 months

Sunday 4th January 2015
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Thanks for this thread, I have exactly the same issue.

Dr Mike Oxgreen

Original Poster:

4,101 posts

164 months

Sunday 4th January 2015
quotequote all
Superb diagram, thanks!

So I just need a length of four-core cable between the PIRs to link the lives, neutrals, earths and switched lives together, then wire my light into one of the PIRs in the normal way. It's obvious when you think about it!

I can see myself needing to glue a piece of opaque plastic to one side of each PIR to act as a "blinker" to stop it seeing any drifting flue gases, but apart from that I think it sounds simple enough.

Thanks for all the help!

parisstclair

3 posts

74 months

Monday 29th January 2018
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R1 Indy said:
Yes you can do this no problems.

Here is a very basic diagram I made someone a few years ago

@R1 Indy Sorry to trouble you I'm trying to do the same thing, the diagram you posted isn't showing on here any more presumably as its an old post, I don't suppose you still have it do you?

anonymous-user

53 months

Monday 29th January 2018
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Why not just havr two separate lights? They're so cheap anyway

Wacky Racer

38,099 posts

246 months

Monday 29th January 2018
quotequote all
keirik said:
Why not just have two separate lights? They're so cheap anyway
This.

parisstclair

3 posts

74 months

Monday 29th January 2018
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Here is my situation..

I currently have one motion detected flood light which you can switch off by a switch inside the house, this would be where I took the power from. down the right side of my house is where I keep my motorbike but when I drive in through the gate at night I cant see sh*t so want to have some lights down there. my plan was to have a PIR down there and one where the flood light is currently to switch both of them on. so basically I all lights will come on whether I come in through the gate or step out the back door. Any suggestions?

Accelebrate

5,244 posts

214 months

Monday 29th January 2018
quotequote all
Here's the diagram:



I followed it a year ago, works great. We had a single PIR switching on multiple outside lights as you walked up the drive. The problem was it didn't work if you were leaving the house until you were halfway down the drive. I added a second PIR pointing towards our front door on the edge of a front canopy.

parisstclair

3 posts

74 months

Monday 29th January 2018
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That's great thanks a lot, very helpful! biggrin

Ydnaroo

288 posts

201 months

Monday 29th January 2018
quotequote all
I wanted to fit a light to the side of my house where there is a balanced flue and ended up getting one of these which work on a microwave detector rather than PIR. The microwave detector is not triggered by heat. They do 30W & 50W versions as well. The lamp is setup using a small remote control rather than controls underneath the sensor.