On-off-on for PIR override - The regs UK

[RockySundae]

Hi all, familiar with electrical but not domestic regs. The supply to the outside is existing so I don't believe this is notifiable work under part P, if it needs another form of sign off then happy to get a domestic elec in but would like to understand the operation regardless.

I have a situation where there is an outdoor PIR sensor, and two lights. These are controlled from a double switch plate in the kitchen on the lighting circuit.

The aim is to have both lights independently controlled, and the ability to switch either light from PIR control or manual override.

The crude diagram here is one method I can think of doing it, but involves using the COM on the two centre-off SPDT switches as the output (switching between PIR switched live on L1 and domestic supply live on L2). Ideally to avoid switching the supply to the PIR so it does not need a 30 sec reboot sequence each time.

Is this a no-no in the regs or permissible so long as sleeving/tags are used?

Alternatively I could take the below approach but would require more cabling, the supply to the PIR would be switched, line voltage present on PIR switched live and not the PIR live, and would I believe necessitate a second PIR to control Lamp 2.

Any thoughts on the above, or alternative solutions would be greatly appreciated

 

[EFLImpudence]

Haven't you over complicated things?

Do you just want the lights to be controlled by the PIR with an over ride switch, either individually or jointly - or

do you actually want the ability to switch off the PIR operation at times.



The centre off (on-off-on) switches are not DPST.

 

[RockySundae]

Haven't you over complicated things?

Do you just want the lights to be controlled by the PIR with an over ride switch, either individually or jointly - or

do you actually want the ability to switch off the PIR operation at times.



The centre off (on-off-on) switches are not DPST.

Apologies, correct to on-off-on, SPTT?

The idea is to have one PIR sensor and two independent lights that can be:
Under PIR control,
Off,
Or manually on.

 

[skenk]

Picture 1 looks fine, you can use the common terminal as permanent live

 

[RockySundae]

Picture 1 looks fine, you can use the common terminal as permanent live

The concern I had with picture 1 is that the permanent live would be on the L2 terminals, and a switched live from the PIR would be on the L1 terminals, with the common terminal being used as the output to the light, is there anything in the regs about this?



In the interest of reducing complexity, I could do the following:
SPDT on/off for the small lamp,
On-off-on (PIR-off-on) for the PIR and floodlight, however switching this to override would disrupt the live to PIR:

Would a live feed to the SL with no live to the L terminal of the PIR, damage the sensor?
Given only enough space for two switches, is there a simple approach to having a permanent live to the PIR whilst retaining the ability to switch the floodlight between PIR,off,on?

The easiest way I could think of resorts back to having L1/L2 as Live/Switched live inputs, and COM as the output

 

[skenk]

The concern I had with picture 1 is that the permanent live would be on the L2 terminals, and a switched live from the PIR would be on the L1 terminals, with the common terminal being used as the output to the light, is there anything in the regs about this?

it's fine. I meant to say "you can use L2 as permanent live" (or L1 or com)

In the interest of reducing complexity, I could do the following:
SPDT on/off for the small lamp,
On-off-on (PIR-off-on) for the PIR and floodlight, however switching this to override would disrupt the live to PIR:

Would a live feed to the SL with no live to the L terminal of the PIR, damage the sensor?

Use pic 1 and that won't happen, but no I'd have thought it's unlikely. as you say this will initiate a reboot and the light will come on for 30 seconds

 

[SUNRAY]

Hi all, familiar with electrical but not domestic regs. The supply to the outside is existing so I don't believe this is notifiable work under part P, if it needs another form of sign off then happy to get a domestic elec in but would like to understand the operation regardless.

I have a situation where there is an outdoor PIR sensor, and two lights. These are controlled from a double switch plate in the kitchen on the lighting circuit.

The aim is to have both lights independently controlled, and the ability to switch either light from PIR control or manual override.

The crude diagram here is one method I can think of doing it, but involves using the COM on the two centre-off SPDT switches as the output (switching between PIR switched live on L1 and domestic supply live on L2). Ideally to avoid switching the supply to the PIR so it does not need a 30 sec reboot sequence each time.

Is this a no-no in the regs or permissible so long as sleeving/tags are used?

View attachment 299845


Alternatively I could take the below approach but would require more cabling, the supply to the PIR would be switched, line voltage present on PIR switched live and not the PIR live, and would I believe necessitate a second PIR to control Lamp 2.

View attachment 299846

Any thoughts on the above, or alternative solutions would be greatly appreciated

I have done EXACTLY your first picture a number of times and there is nothing wrong with it, especially if it's the easiest from a wiring point of view.

 

[JohnW2]

The supply to the outside is existing so I don't believe this is notifiable work under part P ...

That's correct if you are in England. If you were in Wales, I think that any 'outdoor' electrical work would probably be notifiable, even if it utilised an existing outdoor supply.

As for the rest, I agree with what others have said - essentially that your initial proposal looks fine. I'm not really sure what it was about this that you thought might be contrary to some regs..

Kind Regards, John

 

[robinbanks]

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