Bog standard 4 entrance brown junction box (lighting) but ..

[p_a_johnson]

Spotted something else in the loft (lighting circuit) that I'm not sure about whether it is safe. I presume it is part of the original installation.

Please advise if I need to replace with something beefier.

Bog standard brown 4 terminal junction box but has 7 1mm 2 core (or there abouts!) lighting cables feeding the permanent live for all upstairs by the looks of it - it appears that everything spurs off this in the loft.

The junction doesn't look heavy duty at all and am worried that there may be too much load on the single junction???

Do I need to change this as I rewire with 1mm t&e?
What would I replace it with? Two junctions linked or a single beefier unit???

Also, is 1mm enough for normal domestic lighting or should I be upgrading to 1.5mm? - the most any of the upstairs fittings are pulling in my 3 bed semi is 3 X 60W bulbs - (P = VI so 180/240 = 0.75 A ... I think!).

 

[Big_Spark]

PAJ, firstly the junction box, if it is largenough to accomadate the 7 cables, then it is likely to be a 4 or 6 way 20A JB, so it can handle the loading no problem. If it is really old, it may be a 10A 4 way, but even then there is no loading problem.

Regarding your cable, 1.0mm is sufficient for your needs.

Your calculation is sort of correct.

I=P/V = 180 / 230 = 0.8A

If you do the calculations using 230V, you will always be right on cable choice.

 

[MANDATE]

Hi PAJ,
I was just thinking if your going to re-wire are you still going to have 7 cables in one junction box. Every modern ceiling rose acts as a junction box so why would you need to retain it. I can understand using a junction box to divide the upstairs lighting from downstairs.
I dread the thought of trying to get 7 wires in one of those terminals in a JB

 

[ban-all-sheds]

...Regarding your cable, 1.0mm is sufficient for your needs...

But 1.5mm would be better, and virtually the same price.

 

[securespark]

Why better?

It is more cumbersome in some situations like pulling through......

1.00mm2 is entirely acceptable, more flexible, and easier to drag through.

 

[ban-all-sheds]

1) You don't exactly need to live in a mansion before the run from the CU under the stairs up to the loft and around to every light fitting gets marginal for VD.

2) Future proofing, particularly for downstairs lighting circuits, e.g. to cope with someone deciding to put 2 x 500W floods outside...

 

[breezer]

VD being voltage drop

 

[securespark]

Phew!! I thought for a moment.................................

 

[p_a_johnson]

... but I am OK to run 1mm then if that's what I have?

 

[securespark]

Well, point taken about VD from Ban.

1.00mm2 should be good for approx 36m run at 6A, 21m at 10A.

1.50mm2 should be good for approx 55m run at 6A, 33m at 10A.

Given no corrections.