PIR into an existing light circuit

[chris1850]

I realise that it is usual to incorporate a seperate switch for a PIR. However, is it OK to do without this and simply lead a spur from an existing circuit directly to the PIR and from there to the floodlight? I realise that the floodlight will only work when the existing light circuit is switched on.

Thanks

 

[londonboy]

Pefectly fine.

Some PIR's have a force on facility, so if you flick the switch on and off a few times it will come on regardless.

 

[bernardgreen]

Some PIR's have a force on facility, so if you flick the switch on and off a few times it will come on regardless.

It won't come on if the switch is OFF as it has no power when the switch is off

Not really a good idea to have a PIR without a switch. If the PIR fails in the ON position your flood light will be on all the time the lamp it is connected to is on.

 

[londonboy]

Sorry I mis read the post.

Thought the light would have been controlled by a spur.

 

[bernardgreen]

I gave up using PIRs that had their mode of operation set by switching the supply to them on and off so many times per second. Power cuts had a habit of putting them into "always on" mode.

Instead I suggest using a dual gang switch and triple and earth to the PIR for simpler mode setting by switching Live to and Switched Live from the PIR