What's a "Supply Live" cable?

[Jupiter01]

I want to replace a standard ceiling rose with one of these:

It has a terminal block with a brown and blue wire which is connected to the light fitting at one end and is expecting two incoming wires. The instructions state:

At the ceiling I have the following cables:
1. feed in
2. feed out
3. switch

I would have thought that the neutrals from all 3 of these need to be connected into the neutral terminal of the light (using a wago connector to combine these and then take a single wire to the terminal block on the light due to space restrictions - I suspect) and the switch live wire (blue with brown sleeving) is what will connect to the "L" terminal. Is this correct?

I am thrown by the "Supply Live (normally brown or red)" description in the instructions.

Thanks in advance.

 

[bernardgreen]

3. switch

I would have thought that the neutrals from all 3 of these need to be connected into the neutral terminal of the light

The blue wire in the switch cable is NOT Neutral.....It is switched Live.

If you connect it to the other Neutrals then when you switch the switch ON the switch will connect Live to Neutral and blow the fuse or trip the MCD, and also damage the switch.....

 

[stem]

The 'Supply Live' is from the switch and is made live when the light is switched on.

It sounds like you have a 'loop in' ceiling rose. If you scroll down you will find details of how they are wired in the Wiki here.

 

[Jupiter01]

sorry @bernardgreen I didn't intend that. I appreciate the Switch blue (with brown sleeving) is the Switch Live.

That's for clearing that up @stem. I just wasn't familiar with the "Supply Live" term as I thought it suggested Live from the permanent Live cables. Is this a universal expression when referring to the Switch Live?

If someone has doubts (like me!), its then compounded further by the suggestion that this wire is "brown/red". It's blue with a brown sleeving.

Is the actual meaning implicit and entirely obvious to a "proper" electrician or is this sloppy language?

 

[bernardgreen]

is this sloppy language?

It is lack of knowledge in the people who write the instructions. They do not realise that in the UK the ceiling rose is also a junction box for the supply to the lamp and to other lamps in the house.. They write instruction for systems where there is only one cable to the lamp and the junction box is elsewhere and not in the ceiling rose.

 

[ericmark]

sorry @bernardgreen I didn't intend that. I appreciate the Switch blue (with brown sleeving) is the Switch Live.

That's for clearing that up @stem. I just wasn't familiar with the "Supply Live" term as I thought it suggested Live from the permanent Live cables. Is this a universal expression when referring to the Switch Live?

If someone has doubts (like me!), its then compounded further by the suggestion that this wire is "brown/red". It's blue with a brown sleeving.

Is the actual meaning implicit and entirely obvious to a "proper" electrician or is this sloppy language?

If we were to use the correct language as laid out in the regulations, it also causes problems, we know how a ceiling rose works, and we tend to ignore instructions. However it should say:-
Connect the supply switched line (Normally black with red sleeve or blue with brown sleeve) to fitting line (marked L) on the terminal box.
Connect the supply neutral (Normally black or blue) to fitting neutral (marked N) on the terminal box.
Connect the supply permanent line (Normally red or brown) to an extra terminal block not provided as this is not a British fitting together.

Note Live refers to both line and neutral, just like low voltage AC is between 50 and 1000 volt, but it seems not in USA so even in UK suppliers use USA terms rather than international ones.

 

[Jupiter01]

Connect the supply permanent line (Normally red or brown) to an extra terminal block not provided as this is not a British fitting together.

Is this a rarity altogether? Apart from a ceiling rose, I don't recall fitting any lights which have a "loop" terminal for Live cables.

 

[ericmark]

Is this a rarity altogether? Apart from a ceiling rose, I don't recall fitting any lights which have a "loop" terminal for Live cables.

You haven't lived then I have seen loads, specially fluorescent fittings.

 

[stem]

'Loop in' does seem to be a UK thing, I don't recall seeing them anywhere else in my albeit limited experience of overseas wiring, and as many fittings are manufactured overseas.......

 

[Taylortwocities]

Is this a rarity altogether? Apart from a ceiling rose, I don't recall fitting any lights which have a "loop" terminal for Live cables.

You REALLY need to get out more!