Wiring up a PIR

[Steve Maskery]

Afternoon chaps.

I've been given an outdoor globe PIR light. It's never been installed, but it is a few years old and the instructions are missing.

The connector block inside has 4 connections labelled
N (with a blue wire), ⏚(with no wire), L (with a brown wire) and L' (with two white wires).

My q is - What do I do with L'?

I've googled but to no avail.

Ta.

 

[sunnybob]

L is live, N is neutral the upside down xmas tree is earth.

Logicaly the two white wires are the lamp wires that go through the pir to provide power to the light when the pir makes the contacts.

 

[jnw010]

I think there is normally a "Live out" which you can use to run another light/lights up to a couple hundred watts.

 

[Eric The Viking]

Probably:
Blue: neutral
Earth, earth
Brown (live): permanently-on live supply
"White" lives: Switched mains, to force the light on, as required. The switch goes between brown and white.

It's easy enough to wire it up to try it. If you do that in daylight, It shouldn't be triggered by the PIR detector, but if I'm right about the switch, that would cause the light to come on.

Obviously, you don't need the extra switch.

Somewhere on the circuit board, usually near the PIR unit itself, there are probably two pots. One adjusts the duration of the "on" period after it's been triggered, and the other (if it exists), the threshold of darkness at which it begins to work, to stop it operating unnecessarily in cold weather. They should be labelled, but may not be. You get the precise triggering by physically angling the sensor, and/or swapping out the fresnel "compound-eye" lens (slightly opaque plastic).

 

[Steve Maskery]

Sorted, thank you all.
I don't have to do anything with the L'. It just works.

It just so happened that my mate Stuart came round, and he is a retired electrical engineer. He had a look at it and said it was fine. The one disconcerting part was that we could not find a live wire input. I had turned the power off of course, but back on there was nothing showing on my neon screwdriver. Up a ladder, with rubber feet, there was not a good enough earth.

It turns out that the light is wired into the ground floor sockets somewhere, we don't know where, presumably somewhere under the floorboards upstairs and does not appear to be switched. The electrics are bit dodgy in this house. I found out, the hard way, that one socket in my bedroom is wired on the ground floor sockets circuit...

Stuart reckons that L' probably gets live when the light comes on, so it can be used to drive a slave light. We did not test that though.

Thanks all.

 

[sunnybob]

Steve, ditch that neon screwdriver. Its potentialy lethal. Think about it, youre sticking your finger direct onto a live wire, through a very (very) cheap resister that can fail open or closed at any time.
The last company I worked for as a service engineer in the UK regarded an engineer having one of those in his tool kit as a disciplinary offence.
Multitesters are far more reliable and safe, and are not dear.

 

[RogerS]

Steve, ditch that neon screwdriver. Its potentialy lethal. Think about it, youre sticking your finger direct onto a live wire, through a very (very) cheap resister that can fail open or closed at any time.
....

Don't agree with that. if the resistor fails open circuit then there is NO circuit...so no danger. I have never heard of a resistor failing short circuit (or closed as you put it). The reason why a company would take dim view of using them is nothing to do with them electrocuting the operator (which is going to be bloody hard unless the user is standing with bare feet on an earthed ladder) but to do with their functionality..or lack of. If they glow then there is a live circuit. If they don't glow then all that tells you is that they don't glow.