Lighting wiring help needed

[Iggifer]

So I will have two red wires in a block, the two black wires to neutral and live on the new fitting and all earths into earth. Where would you put the blue and brown wires from the attic light? Are you saying the brown live wire can go with the Reds? What about the neutral- attached to the neutral on the new fitting ?

Yup, brown with the reds and blue with the neutrals.

However, you aren't going to know which is your neutral and which is your switched live without a tester.

You can connect a basic lamp to the reds, and then try it in each of the blacks you have - the one it works in will be the neutral. Good idea to mark the other black somehow (ideally sleeving) so that you know it's the switched live.

 

[ban-all-sheds]

This is all irresponsible and wrong.

 

[Lucy6892]

Would you care to elaborate? Thanks

 

[sparkwright]

I think he referring to the 'guess and check' method to identify the switch cable.

A safer, easier way to identify the switch cable may be to go into the attic and trace the cables - you should be able to find which cable disappears to the switch.

 

[Lucy6892]

Thanks sparkwright, that's exactly what we were going to do!

The advice on here has really helped, will let you know how we get on

 

[ban-all-sheds]

I think he referring to the 'guess and check' method to identify the switch cable.

And the whole exercise of facilitating people doing electrical work when they don't actually understand it.

 

[sparkwright]

Let me re-cap all that's been said while you're tracing the cables.

Sometimes helps to clarify when info is all over the place.

Switch cable BLACK gets red sleeve put over it and goes to LIVE of the light fitting.
Remaining BLACK and BLUE to the loft light goes to NEUTRAL of the light fitting.
Two REDS and the BROWN to the loft light all get joined up in a connector block on their own (with the loft brown in this terminal the loft light is live all the time, but can be controlled by the built in switch you have described, so you won't need to turn the bedroom light on for the loft light to work).
All earths joined together, connect to the earth terminal on the light fitting if there is one (any bare earth wires must be sleeved with green and yellow sleeving).

 

[sparkwright]

As Ban says, it seems you don't really understand it, so let me explain simply how it works.

Live and neutral comes in at the rose. Joined here are another live and neutral which go to the next room - in this case the loft.

The third wire is the switch cable. The switch cable goes from the light fitting or ceiling rose to the switch.

From the live mentioned at the rose (known as the permanent live), a wire goes to supply the switch. At the other side of the switch is another wire (known as the switched live) which goes directly to the live terminal of the light.

You see, the switch cable contains permanent live and switched live, and NOT live and neutral. This is why the black switch wire should be sleeved with red - to indicate it's NOT neutral.

The switch therefore only switches the live, and not the neutral.

Hope this helps you to understand how lighting circuits are wired.

 

[Risteard]

Good idea to mark the other black somehow (ideally sleeving) so that you know it's the switched live (sic).

Actually, it is a requirement if using cable of the incorrect colours - not merely a "good idea".

 

[333rocky333]

wheres this white wire everyones on about

 

[333rocky333]

ok sussed it now, wouldnt it have made sense to include it in the pic

 

[securespark]

It is here: