Double gang Two lights

[ChrisGGG]

OK I'm pretty certain there is no permanent live going to the back room lighting circuit. I had a spare one gang switch which I attached to the black and red from the back room and got nothing at all.

There are only three wires going into the ceiling rose, I believe that those three wires go straight to the light switch because if they went to a junction box I should have a permanent live, and they can't be in a loop from the front room as there would be more than the three wires. Does this sound right?

So now the question is, can I wire the switch how I would like without the permanent live.

 

[ban-all-sheds]

OK I'm pretty certain there is no permanent live going to the back room lighting circuit. I had a spare one gang switch which I attached to the black and red from the back room and got nothing at all.

That sounds like guesswork.

It sounds like you sticking wires into terminals to see what happens.

Please STOP trying to do electrical work by guessing and trial-and-error.

There are only three wires going into the ceiling rose, I believe that those three wires go straight to the light switch because if they went to a junction box I should have a permanent live, and they can't be in a loop from the front room as there would be more than the three wires. Does this sound right?

What sounds right is you using a multimeter (or other continuity testing device) to find out whether the wires are as you hypothesise.

So now the question is, can I wire the switch how I would like without the permanent live.

Not unless you would like it to only work when another switch is on.

 

[Risteard]

Yes, according to the regulations -
but for two switches with four conductors, (or two switches with ten conductors - two two-way circuits) what is the point?

The point is to indicate that it is a phase/line conductor.

Over here you would never see anyone sleeving brown & blue (previously red & black) anyway, as everyone uses twin brown (and previously twin red). Incidentally, BS 7671 states that conductors are preferably to be identifiable throughout their length.

And in a neighbouring county it is actually forbidden to oversleeve brown & blue.

It is frankly backward not to use twin brown.

 

[JohnW2]

The point is to indicate that it is a phase/line conductor.

That is what the regs say - but, as has been observed, it really does not achieve anything in the context of any sort of ordinary light switch - unless you can think of any situations in which a conductor connected to such a switch would not be a "phase/line conductor".

Kind Regards, John

 

[Risteard]

The point is to indicate that it is a phase/line conductor.

That is what the regs say - but, as has been observed, it really does not achieve anything in the context of any sort of ordinary light switch - unless you can think of any situations in which a conductor connected to such a switch would not be a "phase/line conductor".

Kind Regards, John

The point is not everyone working on the switch is aware of this, as can clearly be seen from numerous topics here with people asking what to do with "the neutral(s)".

 

[JohnW2]

The point is not everyone working on the switch is aware of this, as can clearly be seen from numerous topics here with people asking what to do with "the neutral(s)".

Maybe, but it's not even as straightforward as we might like to think, since a S/L is only sometimes (often not all that frequently) actually at line/phase potential. Many light switches spend much more time 'off' than 'on', and anyone undertaking measurements in that state would find that the S/L was actually at neutral potential (via the load), not line/phase potential.

Kind Regards, John

 

[Taylortwocities]

anyone undertaking measurements in that state would find that the S/L was actually at neutral potential (via the load), not line/phase potential.

Which is exactly why a blue sleeved brown / black sleeved red is an appropriate way of marking the conductor,

 

[JohnW2]

anyone undertaking measurements in that state would find that the S/L was actually at neutral potential (via the load), not line/phase potential.

Which is exactly why a blue sleeved brown / black sleeved red is an appropriate way of marking the conductor,

Mainly for the benefit of others ... when you say "blue sleeved brown", I presume you mean "blue, sleeved brown" and not "blue-sleeved brown"?

As I presume you understand, my point was that it's not necessarily totally logical to use brown (or red) to identify a conductor which spends most of its time at neutral potential. If one really wants to identify conductors at a light switch, a totally different over-sleeving colour to indicate 'sometimes line potential, sometimes neutral potential' might have been a better choice!

Kind Regards, John

 

[EFLImpudence]

Yes - if perfect clarity were the intention marking with 'L' and 'SL' (or designated colour) could easily have been the instruction.

Marking ALL conductors present with a single identifier colour (or 'L') to signify a (permanent or occasional) line conductor does nothing to help and is therefore pointless. Even an actual brown (or red) conductor cannot be relied on as being the permanent supply line.

 

[Risteard]

Marking ALL conductors present with a single identifier colour (or 'L') to signify a (permanent or occasional) line conductor does nothing to help and is therefore pointless. Even an actual brown (or red) conductor cannot be relied on as being the permanent supply line.

Of course it helps. It identifies that it is a line conductor.

It is completely and utterly irrelevant whether it is always energised or not. The fact is that people know that it is a line conductor and therefore at a potential of 230V to Earth. They also know not to connect it to the system neutral which is at Earth potential.

 

[EFLImpudence]

Of course it helps. It identifies that it is a line conductor.

They ALL are and therefore identified by their presence.

It is completely and utterly irrelevant whether it is always energised or not. The fact is that people know that it is a line conductor and therefore at a potential of 230V to Earth. They also know not to connect it to the system neutral which is at Earth potential.

...but they can't tell which is which by looking at the identification.

 

[securespark]

What if the red/black were wired the "wrong" way round at the rose?

Then the wire in L1 would be live and the wire in COM the switch wire?

 

[JohnW2]

What if the red/black were wired the "wrong" way round at the rose? Then the wire in L1 would be live and the wire in COM the switch wire?

and ....?? We are agreed that all conductors connected to a light switch will at times be at line potential, regardless how they are, or are not, 'identified'.

Kind Regards, John

 

[securespark]

...and then that would introduce confusion as the switch with the (black insulated) live attached to the L1 would have to be closed onto the common for the lights to work.

 

[PBC_1966]

It is - but I suspect ONE of the cables may be the other way unless miscommunication and a faulty switch.

If I've followed what's going on, it sounds as though one of the lines might also be open-circuit somewhere. Maybe that's why somebody put the bridge across the switches in the first place?

However some electricians advocate using the black as permanent line so that you know which it is in the ceiling loop.

With appropriate color substitutions, that's how it's done over here: White (normally neutral) is used as permanent live to the switch, black as the switched return. The idea is that at the lighting outlet the connections to the light fixture will then be black & white rather than two white, with less chance of a mix up when a light is replaced.