Caste Metal Light Switch

[unionworkeruk]

I am replacing the open wire and plastic light fitting with a conduit and an old metal light switch or repro switch. The wiring has an earth but one of the switches has only two entry points for wires The other has three so I presume one for an earth.

If I use the one with only two entry points what do I do with the earth wire and would they both be equally safe if there is a way of securing the earth wire in some way ?

The square box is the one with only two entry points for wires

Thanks

 

[Adam_151]

You need to earth the metal parts including the BESA box and the conduit (which is through the BESA box being earthed AND the conduit being tight in the thread). If you look at the BESA box, you will see there is a M4 tapped hole thats helpfully been provided with a brass machine screw (there seems to be a similar earthing point on the switch - although its not clear how this has been done! as this just appears to be a box lid with a toggle switch fitted through it.) You need a suitable 4mm ring crimp to connect onto the M4 bolts. Whats the other end of the conduit, have you got a suitable bush on it... I am of course assuming its not part of a continuous containment system

 

[EFLImpudence]

The wiring has an earth but one of the switches has only two entry points for wires The other has three so I presume one for an earth.

It appears you need to learn what switches do.
https://www.flameport.com/electric/lighting_circuits/lighting_switcharrangements.cs4

The square box is the one with only two entry points for wires

What is this square box of which you speak?

 

[StephenOak]

What is this square box of which you speak?

The round box is shown in the inline picture, the square box is shown in the thumbnail picture at the bottom (click to enlarge). I guess he added the two pictures in different ways.

 

[EFLImpudence]

Oh right, sorry. That's usually just a thumbnail of the main picture.

 

[StephenOak]

That's usually just a thumbnail of the main picture.

That was what I thought at first, but I when I could not see the square box I opened it just to be sure.

 

[sparkwright]

The wiring has an earth but one of the switches has only two entry points for wires The other has three so I presume one for an earth.

No.

Not correct at all.

The switch with three terminals is a 2 way switch. You must not connect an earth to those three terminals. There is an earth terminal on the metalwork of the switch faceplate.

 

[unionworkeruk]

Thanks Sparkwright I get it now. I have a bush to go on the other end which will be flush to the ceiling. I can see the rounded switch fitting has the earth terminal on the metal plate.

The wiring is old so am I correct in that the red wire is connected to com and the black to L1 ?

As there is no fitting for the earth wire on the other switch is there anything I can do so it can be used ?

Both photos were sent the same way so you could see the detail

Thanks

 

[333rocky333]

Looks thick enough to drill and tap a 4mm hole in the rear face and earth it same as your round box
Be carefull not to crack the porcelain switch, personally i would take the guts out till the box is sorted and fixed to the wall

 

[Adam_151]

I'd do as rocky says... you can buy M4 rethreaders if you don't have a set of taps.

But you MUST earth it, the reason it doesn't have an earth terminal is because it was expected to be installed as part of a complete conduit installation where the conduit was the earth

 

[winston1]

The wiring is old so am I correct in that the red wire is connected to com and the black to L1 ?

That is one way of doing it. You could also connect the red to L1 and the black to common, it does not really matter. But you should put a red sleeve on the black wire.

 

[SUNRAY]

That is one way of doing it. You could also connect the red to L1 and the black to common, it does not really matter. But you should put a red sleeve on the black wire.

Recently had to change all the red sleeves to brown, wherever changes had been made on a referb, before the inspector would accept.

 

[JohnW2]

Recently had to change all the red sleeves to brown, wherever changes had been made on a referb, before the inspector would accept.

Are you talking about multi-core cables (T&E or whatever), such that you ended up having a cable with one conductor identified by black red and the other by brown?

If so, is that even allowed? Mixing 'old' and harmonised colours in the same cable seems very odd!

Kind Regards, John

 

[333rocky333]

If all the install is Red and Black, it makes sense to mark Red, however if some Brown already exists, then i would sleeve both Red and Black cores Brown and check for a Label at CU

 

[333rocky333]

Recently had to change all the red sleeves to brown, wherever changes had been made on a referb, before the inspector would accept.

Would that not leave you with one Red and a Black marked Brown