Adding PIR to existing Stairwell timer setup

Chris_chris · Nov 12, 2021

I was looking for some advice on common wiring styles for stairwell delay lighting circuits. So I can figure out what has been done in the existing wiring since I have committed to try and add some PIRs to an existing stairwell delay circuit in the block of flats that we are living in.

The current situation:
multiple rail mounted 'eltako sts12' stairwell timers (cant find manual online but very similar to attached photo of a current model)
multiple standard 1 gang wall mounted momentary switches

What I have managed to find to install:
2 x 1 Gang wall mounted PIRs 2 wire switched live (i.e. no neutral needed, live IN, switched live OUT) - so latching switch equivalent (pic attached)

My plan:
To replace a couple of the strategically placed momentary switches at the entrances to the building so that it automatically turns on as you enter, and you can also use the momentary switches on other parts of the building. I was thinking about using some sort of monostable non latching relay to simulate a momentray swtich (but with a 5 second press rather than the usual quick press, becuase 5 seconds is the shortest PIR setting I have) this will work becuase the timers are simple and dont have a anti-block feature.

Before I embark on this new setup I have some questions

QUESTION 1 - It doesnt make sense to me the wiring in the wall boxes of the momentary switches that I dont see a live on neutral engerised wire in the wall boxes based on either the 3wire or 4 wire connection diagrams (pics attached) that the original electrician you would expect would have followed. Does anybody know why this is? Is there another "standard" way of doing such setups that isnt as per instructions from manufacturers?

QUESTION 2 - Has anybody inserted such as stairwell setup with both momentary switches and PIRs, and if so, how have you done it?

To add complication to this, im doing this in Cyprus and thus restricted to using equipment that is avaliable here (which is not a lot) or limited things I can get via amazon.

Many thanks in advance folks for any help or advice.

buzzlightyear · Nov 12, 2021

IMO, you should seek a spark to sort the wiring out for the internal PIr.
before you start making a mistake.

Chris_chris · Nov 12, 2021

buzzlightyear said:
IMO, you should seek a spark to sort the wiring out for the internal PIr.
before you start making a mistake.

I dont follow how will a local sparkie be able to sort out the wiring that I cant? I forgot to mention that consumer units are not marked up literally at all and its all using old black and red 2 core without any taping.
The local electricians here are mainly useless and they arent "professionals" as such. I asked a electrician I know here and he hasnt done stairwell wiring before and he is only person I would trust with a response.

MJPD29 · Nov 12, 2021

Chris_chris said:
I dont follow how will a local sparkie be able to sort out the wiring that I cant? I forgot to mention that consumer units are not marked up literally at all and its all using old black and red 2 core without any taping.
The local electricians here are mainly useless and they arent "professionals" as such. I asked a electrician I know here and he hasnt done stairwell wiring before and he is only person I would trust with a response.

Better than of the local electricians. You must be a talented individual. Any chance you plaster along side your electrical work?

Chris_chris · Nov 13, 2021

Matthewd29 said:
Better than of the local electricians. You must be a talented individual. Any chance you plaster along side your electrical work?

Yes I an an electical engineer in fact as one of my masters undergraduate degrees since you ask. Additionally I can plaster also, but not ceilings, im no good on stilts.
Unfortunately I'm clearly not going to get any useful advice from you.

MJPD29 · Nov 13, 2021

Chris_chris said:
Yes I an an electical engineer in fact as one of my masters undergraduate degrees since you ask. Additionally I can plaster also, but not ceilings, im no good on stilts.
Unfortunately I'm clearly not going to get any useful advice from you.

Unfortunately not, I don't advise on such subjects to DIYers as to do so would be reckless especially when working in a public environment such as a stairwell in flats. My advice is stick to the day job.

pc1966 · Nov 13, 2021

No matter how technically competent you are this is not your property, it is communal. If you are not insured for such work and something goes wrong (or simply the finger is pointed at you following any fault) you could be in all sorts of serious trouble. For that reason alone you would be far better to get a local sparky to sort it out.

Chris_chris · Nov 14, 2021

Im not sure, what part of of im a qualified electrian and electrical engineer plus im also a electronic engineer. Im not sure you got that. Im not an ameteur, just never done multiple stiarwell lighting before, Im looking to get advice on how sombody could have wired the satirwells from folks who have expereince of doing stairwell lighting before becuase clearly the sparky who did this wiring was cutting every corner there was looking at the rest of the unsafe wiring they have done.

The reason im asking is that I DONT want to re-wire the whole stairwell circuit properly, as per the standard 3 wire spec, unless I have to so I can add the PIRs in. Mainly because I cant get the correct PIR here, plus it a big job, as there is no trunking in the walls it looks to be wet rendered in.

Plus there is no qualification or trade body for cypriot electricians so most of them cant even wire a plug hence why I would not trust them. Ive tried to use them before and they just make things up.

Who would you get in trouble with here exactly because im UK educated not cyprus? there is no planning control here, nor is there any electrical inspections or regulations that any sparky follows (even though there are regulations on paper) even on commercial or multi occupancy buildings. The only time anything is ever seen (not inspected or tested) is by the state electric company is when the building is built or if the electricuty has been cut off centrally for more that 3 years.

If you just dont know what to say, becuase you cant advice because you also like me have not extensive expereince of stairwell lighting then just dont say anything.

sparkymark77 · Nov 14, 2021

Chris_chris said:
Im not sure, what part of of im a qualified electrian and electrical engineer plus im also a electronic engineer. Im not sure you got that. Im not an ameteur, just never done multiple stiarwell lighting before, Im looking to get advice on how sombody could have wired the satirwells from folks who have expereince of doing stairwell lighting before becuase clearly the sparky who did this wiring was cutting every corner there was looking at the rest of the unsafe wiring they have done.

The reason im asking is that I DONT want to re-wire the whole stairwell circuit properly, as per the standard 3 wire spec, unless I have to so I can add the PIRs in. Mainly because I cant get the correct PIR here, plus it a big job, as there is no trunking in the walls it looks to be wet rendered in.

Plus there is no qualification or trade body for cypriot electricians so most of them cant even wire a plug hence why I would not trust them. Ive tried to use them before and they just make things up.

Who would you get in trouble with here exactly because im UK educated not cyprus? there is no planning control here, nor is there any electrical inspections or regulations that any sparky follows (even though there are regulations on paper) even on commercial or multi occupancy buildings. The only time anything is ever seen (not inspected or tested) is by the state electric company is when the building is built or if the electricuty has been cut off centrally for more that 3 years.

If you just dont know what to say, becuase you cant advice because you also like me have not extensive expereince of stairwell lighting then just dont say anything.

What have you got wiring wise at the existing switches?
It sounds like it should just be a straight swap - the existing momentary switch is just closing a contact and as long as the pir doesn’t need a neutral then that would do the same thing and trigger the timer. It shouldn’t matter if the shortest trigger time is 5 secs, that would just be like pushing the switch for that long.
I think I might be inclined to swap one switch for a pir - providing you take the necessary precautions of course. The worst that should happen is it won’t work properly and you can put it back to how it was.

newfutile · Nov 15, 2021

in some of our blocks of flats the push button momentary switches send a quick switched live to the staircase time , all the lights are connected to that and stay on for the required time, you may be better off with a microwave light fitting to switch the lights.