Re wiring security light

[paul243]

I am in the process of removing 2 old 150 watt halogen lights switched by 3 old pir's. The system is is fed from a fused switch in a bedroom connected to an adjacent power socket. A cable goes to the loft.
I have removed a cable from the switch which went to one of the old pir's
In the loft the cable splits at a junction box to each end of the house to the old lights. I have disconnected at the junction, removed one of the lights and cable and am left with just a feed to the remaining light which I will replace with one new Steinal PIR light.
The old switch had the facility to turn on the lights if required but would not turn off the lights if they developed a fault and stayed on all night, (one of the reasons to replace)
So can I simply replace the switch with a normal switch to power the new light, leave it on and let the new light be controlled by it's PIR?
Thanks

 

[EFLImpudence]

So can I simply replace the switch with a normal switch to power the new light, leave it on and let the new light be controlled by it's PIR?

You could, but you shouldn't.

The fused switch contains the necessary fuse when lights are supplied by the socket circuit, and

it is double-polled, unlike an 'ordinary' switch, which might be useful if a fault occurs on the light circuit.


Why do you - apparently - seem to think you cannot leave the fused switch on?

 

[paul243]

Thanks for prompt reply.
I think it's wired so that it can be turned on but would not turn off the lights when when a pir failed, thereby leaving the lights permanently on, meaning I had to go to the garage to isolate the whole ring.

 

[EFLImpudence]

Yes, but that was just down to how it was wired; nothing to do with the type of switch.


Just thought - That would presumably mean the supply to the PIR did not go through the fuse, so not exactly correct.

Wire the PIR from the switched-live output and it will do what you want and then you will be be left with a spare wire.

 

[paul243]

Excuse my ignorance but don't really understand that, can you explain please which terminals to use on the switch. I'll take a photo of the switch

 

[JohnD]

...it is double-poled, unlike an 'ordinary' switch, which might be useful if a fault occurs on the light circuit....

External circuits, especially lighting, are very prone to damp and water entry due to rain, which causes the RCD to trip, and an ordinary light switch will not isolate it. You really ought to have a fused DP switch so that you can safely isolate it, including for maintenance and bulb changes.

 

[paul243]

Thanks John,
How do I recognise if I have a fused DP switch?, It certainly has a (pull out) fuse compartment.

 

[EFLImpudence]

Excuse my ignorance but don't really understand that, can you explain please which terminals to use on the switch. I'll take a photo of the switch

Well, at present, for the light and PIR to be on with the switch OFF, then the PIR must be connected directly to the supply wire at the input/supply/in of the switch and then the output/load/out is connected directly to the light which is powered when the switch is ON by-passing the PIR.

You want the PIR to be connected to the switch output/load/out so that it only works with the switch ON.

It might be worth noting that if you want more than one light to come on with one PIR, modern lights with integral PIRs might not have accessible wiring, without dismantling and modifying.

How do I recognise if I have a fused DP switch?, It certainly has a (pull out) fuse compartment.

Most Fused Switches today are double-pole.

If you have terminals in and out for the Neutral wire it is double-pole.

 

[paul243]

Had the switch off and it does indeed have L and N in and out. Pull out fuse "tray"
Cable out also has a yellow wire which I assume was for the separate PIR's which are now removed.
So can I now simply use this cable to the PIR light using 2 wires for live and neutral. And yellow for earth.?
Just to clarify, I want the facility to turn the light OFF if a fault occurs, not to turn ON permanently.
Thanks again.

 

[bernardgreen]

Having the two pole override OFF switch enables complete isolation if the lamp is damaged or has water in it. Leaving the Neutral connect means the RCD for the circuit can be tripped due to leakage of current from Neutral to Earth in the lamp.

 

[paul243]

Thanks Bernard, so does that mean I can proceed as in my last post?
PS the lamp has L , N and E terminals, plus a further L which is blocked off for access.

 

[paul243]

Update-
I've now wired and fitted. Via existing DP fused switch. Simple L and N and E.
Switch on ,fine but won't turn off, been on now for an hour.
Any thoughts?
Thanks

 

[Harry Bloomfield]

Update-
I've now wired and fitted. Via existing DP fused switch. Simple L and N and E.
Switch on ,fine but won't turn off, been on now for an hour.
Any thoughts?
Thanks

It reads as if you may have connected your live feed to the unit, to the output of the PIR's switched live connection. Does the connector block have four terminals?

 

[paul243]

Thanks Harry
Yes it has 4 terminals but one L is blocked to prevent access. This one has 2 internal wires connected. I used only the accessible L N E.