Another loft light wiring question

[Graemevw]

I need to add 2 lights to my loft, one switch.

I had already looked at the wiring diagrams sticky and just went into the loft to see what things up there are like.

Messy is the answer.

The origional rubber wiring has been replaced, its still in place though.

None of the new wiring is clipped in place, its just all looped about loose. I assume it should be clipped to joists?

Anyhow, its the wiring im asking about.

There seems to be one supply from CU to a junction box. Black and red + earth.

From this junction box there are 5 single conductor red cables. One goes to each of the 5 upstairs lights.

There is also one black cable that goes to the nearest bulb holder. I assume this then goes off to each of the other bulb holders.
Each bulb holder has 3 single core conductor cables going to/from it. I assume ones the red, ones the black, and one is to each switch.

How is this system wired? I'd like to have a proper understanding of the circuit but dont want to lift all the insulation and trace every cable so i can work it out.

As for my new loft lights, can i go from the junction box i mentioned? The switch can happily be in line as its half way between the box and the new lights. Is it as simple as taking a 2+E from the box to the switch, then 2 2+E's from the switch, one to each new bulb holder?

Thanks.

 

[PrenticeBoyofDerry]

None of the new wiring is clipped in place, its just all looped about loose. I assume it should be clipped to joists?

yes it should be fixed securely
Anyhow, its the wiring im asking about.

There seems to be one supply from CU to a junction box. Black and red + earth.

From this junction box there are 5 single conductor red cables. One goes to each of the 5 upstairs lights.

light fittings or switch plates?

Each bulb holder has 3 single core conductor cables going to/from it. I assume ones the red, ones the black, and one is to each switch.

Assume? Do you have test equipment to investigate?
Are we excluding the earth/CPC?

How is this system wired? I'd like to have a proper understanding of the circuit but dont want to lift all the insulation and trace every cable so i can work it out.

You need a continuity tester and an approved means of testing for voltage.

As for my new loft lights, can i go from the junction box i mentioned? The switch can happily be in line as its half way between the box and the new lights. Is it as simple as taking a 2+E from the box to the switch, then 2 2+E's from the switch, one to each new bulb holder?

No you need a neutral and also need to know how your set up works.
You can link across the two new lamps with T&E, so they operate by a single switch.

 

[Graemevw]

Seeing your replies has made me realise i didnt write my post very well.

There is twin+earth to the junction box, then 5 live+earth leave it, each one goes to each of the 5 upstars ceiling roses.

There is one neutral+earth from the junction box that goes to the nearest ceiling rose.

Each ceiling rose has 3 single+earth cables, but i havent yet taken down any roses to check further.


I have the tools to test continuity, and voltage, and more importantly i know how to use them safely. I will trace and test the circuit to find out how its run, but thought maybe explaining what i already know might make it obvious to you guys how this circuit works.


So can i not just take live, neutral and earth from the junction box, to the switch, and of to the new lights?

 

[Graemevw]

Just double checked in the loft, removed some stuff, and i was wrong.

live, neutral and earth to junction box.
Neutral of to nearest rose, then of to next, then next etc.

5 lives from JB, one to each switch, then live back up from each switch to the rose.

Makes sense now, none of the wiring is very neat and the way the insulation has been cut you cant see the colour, alot of the time the grey outer sheath hasnt been cut back.

Once i have the new lights in ill tidy it all up i think.

Now i know how its wired i also understand how to link the new lights in.

Thanks

 

[PrenticeBoyofDerry]

Cable run
*Take a feed from the junction box (Phase, neutral and earth) in 1.00mm T&E.
*Take that cable to a one gang switch.
*Then take another length of 1.00mm T&E form switch to first light fitting.
*Then between another 1.00mm T&E between light one and light two.

Connections
*At junction (assuming you are using new core colours)
brown to red (phase)
blue to black (neutral)
sleeve bare CPC/earth conductor in green and yellow pvc sleeving an termiante to earth terminal.
*At switch
Brown from junction box to Com/L terminal on switch plate
Brown to first light fitting to L1 on switch plate
Both blues in connection block.
Earths/CPC sleeved then connected to earth terminal, if non present then together in connection block.
*At first light
Both browns to live of lamp
Both blues to neutral of lamp
Earth/CPC sleeved and terminated at earth terminal or connection block together.
*At second light
Brown to live of lamp
Blue to neutral of lamp
Earth/CPC sleeved and connected to earth terminal or connection block.

 

[PrenticeBoyofDerry]

NB: Might be worth tidying up this set up, as there will be restricted space in the junction box with so many cables connected. Might be worth adding some more junction for switch drops.

 

[Graemevw]

yes, tidying the circuit sounds a good idea.

We have only a little insulation up there. I want the lights so i can clean out all teh cobwebs and do the insulation properly.

Once lit ill remove all insulation, take out the old rubber cables and tidy the lighting cables.

If there not long enough ill re-wire it completely.

Loft space will be insulated and part boarded for some storage, to my mind it makes sense to wire it above the insulation and boarding so it can be got to in the future. Good idea or bad?

 

[PrenticeBoyofDerry]

Ans) Good idea

Though cable for lighting (1.00mm) is generally okay within thermal insulation, as it's current carrying capacity, even after de-rating is satisfactory high enough to deal with a 6A supply.
Any junctions/joints etc.. should be easily accessible for inspection and testing. Also with cable clipped high it will prevent any mechanical damage caused by loft board or fixing of them.

If any other power circuits for sockets or shower are routed in the loft it would also be wise to lift them above the insulation.

 

[Graemevw]

Thanks.

 

[PrenticeBoyofDerry]

My pleasure!