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Hi
Just made up this drawing of a way to wire and test emergency lighting and keep the non-emergency lighting lit.
Has others wired it this way and would it be 18th edition compatible?

I've attached the drawing
 

Attachments

You don't need a two way switch. Use a single pole key switch which only interrupts the permanent live for test purposes. The normal part of the circuit is taken from the Com of the switch along with the line supply.
 

telectrix

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so you need a rocker switch to turn lights on and a keyswitch for testing the EMs. click do modular switches where you can swap the module/s as required. also the PIRs need a permanent L. this can stand being interrupted when testing.
 
  • Thread Starter Thread Starter
  • #5
Sorry maybe I did not describe it correctly. I was wondering if anyone has tried wiring it this way.

I have wired many lighting circuits in the past. Also wiring factory lighting which required the normal lights to stay on whilst the emergency light were being tested.

Back to my drawing

Cabling is a 3 core and earth leaving the board looping into 1st PIR , then in and out of each light and ending at the 2nd PIR

The 2-way Key-Switch is located in a locked cupboard adjacent the main board.
The main board itself shall be locked.
The caretaker from inside the cupboard shall test the emergency lights once a week.

The “Long Range PIR's” shall be located at each end of a corridor.
The corridor has multiple room doors along its length.
The PIR's shall switch the corridor lights on and timed to switch the lights
off after approx 10-15 minutes.

The Black gives a permanent feed to the PIR's and the Emergency Lights.

NORMALLY -
When the Key-Switch breaks the permanent feed the Emergency Light come on.
Non-Emergency Lights shall go out.
The PIR's at both ends lose their permanent feed which should also put the “Normal” lights out.

PER MY DRAWING
As I have wired the Brown to the L2, this L2 is now a switched feed to all of the “Normal” lights. The Normal lights get a temporary switched feed during an emergency lighting test

(The emergency lights - although they have the temp switched feed at them, they won't come on via the switched feed but come on via their battery feed as the permanent has been removed via the key-switch)

Which keeps 'ALL' of the area lit, be it an underground car-park, busy offices, factory floor etc.
 

Lucien Nunes

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I see what you are trying to achieve and how, but there is a snag with the PIRs which are not necessarily designed to handle having their SL outputs energised via the test switch while the PL is switched off. Their output relays link PL and SL solidly together when active, therefore if the test switch is operated when either PIR is active, it will latch to the SL feed and backfeed the supposedly dead PL from it.

Such unintentional misoperation of the PIRs would defeat the discharge test, because the emergency fittings would be lit but not from battery despite the switch being in the test position. I would think this an unacceptable source of error and confusion and would not use this configuration.
 

Vortigern

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No that would not work. Principally because whatever position the switch is in the circuit would still be live. Personally I would use a two pole switch. In fact you would not need the third cable (S/L) as this is already supplied by the PL switched through the PIR so you could do away with the connection of the S/L. But anyway if you did this then all the lights would go out on test which is not an ideal scenario.
 

Lucien Nunes

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The OP's specific intention seems to have been to arrange for the test switch to override the PIRs and force the normal lights on while the em is on test, but without running the necessary additional cables. He appears to have overlooked that a PIR can feed back from SL to PL and therefore invalidate the test. There is no way to achieve the result he wants without at least one more cable core, so that the PIRs can be disconnected from the lights during test.
 
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  • #9
SL to PL would show as Green LEDs showing as on. Also if SL to PL were a problem then no one would be able to wire more than 1 Pir controlling a lighting circuit. I would thing manufactures would have thought. tested and designed for this problem. So SL to PL is not a problem. Also additional cores are not required.
 

Lucien Nunes

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Making the PIR SL live from another source is not a problem while PL remains live, which is the normal state of things when multiple PIRs are wired in parallel. The unpredictable backfeeding only occurs when SL is made live from another source and PL is cut off while the PIR output is on. At that point the PIR output relay is closed and PL remains live by being back-fed from SL, so the PIR electronics stay powered. Only once all PIRs are inactive will the PL lose its last feed, de-powering the PIR electronics and releasing the latch-up condition. If the PIR has a triac output, the effects are unpredictable because the triac is then conducting in the wrong quadrants and may or may not actually hold, but there is still no true disconnection of the PL to instigate the emergency test.

We had a similar thread recently about motorised central heating valves, in which the proving contact must be fed from a separate PL that is not associated with its control input, to prevent exactly the same backfeeding situation occurring.
 

davesparks

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Hi
Just made up this drawing of a way to wire and test emergency lighting and keep the non-emergency lighting lit.
Has others wired it this way and would it be 18th edition compatible?

I've attached the drawing
Why would you want to wire it like that? The PIRs are getting the emergency live instead of a permanent live, this doesn't make sense to me.
There should be a permanent live to the PIRs, this way the lights will continue to operate as normal when the ems are being tested.
Post automatically merged:

I have wired many lighting circuits in the past. Also wiring factory lighting which required the normal lights to stay on whilst the emergency light were being tested.
All normal lighting should stay on when the emergency lighting is being tested. If your test switches are cutting off all lights then something is wrong.
 
  • Thread Starter Thread Starter
  • #12
As per my initial question "Has anyone every wired it this way".

These 60mt corridors have Tray fitted at present. There is no Trunking.
Lighting is being wired in 3-Core & Earth.
2 circuits in the corridor and another circuit at the far end of the corridor doing stairs
The drawing shows there is no need for a 4th core.
Therefore no need for an extra Twin & Earth. (Saving the Planet...…..and me)

I've attached an amended drawing, but the wiring is still the same.


If singles were used I normally run 4 cores.
 

Attachments

Lucien Nunes

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I fear you have rather defeated the point of your original post. You asked whether this configuration would be safe and functional. I explained that while I understand what you are trying to achieve and how you are trying to achieve it, there is a snag that would cause it to potentially malfunction due to the PL of the PIRs being switched off which would in turn render the emergency test function inoperative. I am not sure why you have objected to that statement since it is the type of observation you were asking for. It is not conjecture or opinion, it is based on understanding the internal construction of PIR sensors and relay logic. You can rig up a demonstration for yourself if you are unconvinced.

It is even possible that it would work, if the transit time of the test switch contacts is greater than the release time of the PIR output. However, if it does work, it is working through pure luck based on unknown parameters in the switch and output relay, rather than through correct design, and I only do correct design.
 
You are over complicating this. You just need another cable to interrupt the permanent line to the emergencies only taking all other parts of the circuit out of the equation.
Post automatically merged:

Thinking about it you still only need three cores from the board, ignoring the cpc. A neutral, line for the general lighting and a line for the emergencies.
 
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