Came across a strange wiring set up on a security light I had to change
today. Not seen it before & I change a lot of security lights - they seem
Wired with 3 core + E cable, red, blue. yellow cores.
Old light was wired as follows;
Red - Brown to PIR.
Blue - Blue to PIR & White to Lamp
Yellow tagged "Warning Slave & Override (& something else obliterated) -
White to PIR & White to Lamp.
Switch inside the house operated the light. It was in the On position.
Customer (a regular) had gone out, so I couldn't get into the house to check
the switch (I could turn the circuit off in the garage).
Multi meter between the red & blue gave 230v & between red & yellow gave
The new light only had the facility to wire in L, N & E.
Wired up the new light using the red as L and the blue as N (blanked off the
yellow) and all works exactly as it should, but I couldn't check the switch.
I'm assuming the old light was 'old' and didn't have the auto/manual feature
found on 'modern' security lights, so had been wired with 3 core & E to
allow it to be switched on permanently, overriding the PIR. The yellow
seems as though it would achieve that.
Going back tomorrow for some more work, so I can re wire it if necessary.
There's nothing too odd about this arrangement. It looks as if the PIR is
a 3-wire one, with white being the switch output. Switching yellow to red
bypasses the PIR contact to force the lamp on manually. What you have
done will work fine, but doesn't have this remote override facility (at
Sounds like you got the right idea, the early lights had a 4 way connector
block to facilitate bypass in fact MK made a switch to do just that being
labelled AUTO / MAN
As you say brown is live Blue Neutral and yellow switched live BUT from your
post you say you got 230v across brown & blue plus 230v across brown &
yellow this suggests switched neutral which (although wrong) would work if
Recommend you look at the switch in the house before trying to connect the
You will probably need to swap the red and yellow cables (ie choc block the
red) to allow for manual override and then leave the switch in the on
position until an overide is needed.
The obliterated part of the label was probably a "max wattage for the slave"
The Medway Handyman brought next idea :
Put a choc block on the red to insulate it and use the yellow for the
live. That way you can use the switch to disable the light, or a quick
off plus back on forces it to stay on until the next dawn.