odd wiring

[333rocky333]

Just returned from a job, for certain reasons the job will be passed on to another contracter tommorrow.

Theres 4 rooms tripping an mcb
each room has 1 centre light, they appeared to be 2d though unsure if they were the originals.

However the rooms had 2 way switches, each switch appeared to have many 3 core cables.
there was no second switch in the rooms.
L1 had a Black and a Grey cable
L2 had a Brown, another Brown and another I think was Black
Com had a Black and a Grey cable
So possibly 7 wires in each switch
Just wondering why so many cables, they had used RED rocker switches, only thing I can think is possibly a Second perhaps emergency supply that puts the lights on, even though the switch is off.
It was a care home/ hospital envirement.
Any ideas

 

[deadshort]

Hi, its possible that there is a 'master override' hence the red rocker. The staff may require to switch lights on from a central location in an emergency?

Interested to know if it's the norm in that environment?

DS

 

[AdrianUK]

There is an "old" wiring scheme that uses two way switches to implement an over-ride system. The normal supply is connected to L1 & the switch wire to the lamp is connected to COM. All the L2's are connected together & then to master switch (which should also be fed from the same MCB). The effect is to illuminate all the lights irrespective of whether they were initially on or off but still allow normal switching operation when override is not required.

I use exactly this method to give my alarm system control of the landing & staircase lights in my home. In the event of an intruder or fire alarm activation these lamps will operate.

 

[333rocky333]

I use exactly this method to give my alarm system control of the landing & staircase lights in my home. In the event of an intruder or fire alarm activation these lamps will operate.

That did cross my mind, I recall back in the 80s a lot of our pubs had there lights linked to the alarm systems

 

[JohnW2]

There is an "old" wiring scheme that uses two way switches to implement an over-ride system. The normal supply is connected to L1 & the switch wire to the lamp is connected to COM. All the L2's are connected together & then to master switch (which should also be fed from the same MCB). The effect is to illuminate all the lights irrespective of whether they were initially on or off but still allow normal switching operation when override is not required. ... I use exactly this method to give my alarm system control of the landing & staircase lights in my home. In the event of an intruder or fire alarm activation these lamps will operate.

I did exactly the same in my previous house. Every 1-way-switched light in the house used a 2-way switch (COM & L1), with all the L2s joined together. There were switches just inside the front door and by our bed which connected all those L2's to L, thereby enabling one to illuminate the entire house if one suspected an intruder, and likewise the alarm system connected L to the L2's, again illuminating the whole house.

Kind Regards, John

 

[AdrianUK]

I did exactly the same in my previous house. Every 1-way-switched light in the house used a 2-way switch (COM & L1), with all the L2s joined together. There were switches just inside the front door and by our bed which connected all those L2's to L, thereby enabling one to illuminate the entire house if one suspected an intruder, and likewise the alarm system connected L to the L2's, again illuminating the whole house.

Kind Regards, John

Its also possible to do this with two-way lighting circuits, just not quite so easy. The method is to use a switch (or relay contact) to join the 'strappers' (the wires which link L1 to L1 & L2 to L2) together. The effect is then the same - the lamp will operate irrespective of the position of either (2way) switch.

 

[JohnW2]

Its also possible to do this with two-way lighting circuits, just not quite so easy. The method is to use a switch (or relay contact) to join the 'strappers' (the wires which link L1 to L1 & L2 to L2) together. The effect is then the same - the lamp will operate irrespective of the position of either (2way) switch.

Yes, I realise that, but it detracts from the simplicity of the "1-way" system - which allows all the (1-way) lights to be switched on from multiple places (by switches, alarm relays, or whatever - which simply connect the joined L2s to L).

In fact, in that previous house, where the only 2-way switching was the usual for 'hall and landing' lights, I installed an additional light at the top of the stairway, which had no manual switch, but was simply wired between the 'joined L2 line' and neutral. Landing and hall, as well as every other room in the house (and outside lights!) therefore became illuminated when the L2 line was activated.

Of course, this was 35-40 years ago, in the days of a single lighting circuit and no RCDs. These days. with multiple lighting circuits protected by different RCDs, some relays would be needed!

Kind Regards, John