Cable size: JB to downlight

[gasket]

Hi Folks.

just looking for a quick confirmation here as have found conflicting info in past searches.

Lighting is split into two circuits (upstairs and down) each protected by 6A breakers.

The rings are done in 1.5mm 3-core T&E and there are traditional round plastic junction boxes above each downlight.

A short length of cable runs from each JB to an individual downlight. Downlights are a mix of luceco gu10 / gz10 lampholder fittings like this and some Ansell Edge GU10 downlights like this. All fitted with LED GU10 bulbs.

question is, what size cable should these little runs be? Some places are saying .75mm is enough given the draw from the bulbs, others are saying there can’t be a drop in cable size - so 1.5mm and that you have to assume that someone’ll shove in a halogen in future.

some fittings already have .75mm but happy to go through and change every one if they would benefit from an upgrade.

thank you.

 

[EFLImpudence]

Virtually anything would do for one light.

0.75mm² will be fine.

 

[sparkwright]

As said, 0.75mm2 will be fine - after all, a standard pendant will have something like 0.75mm2 flex - if you want even further confirmation.

 

[securespark]

Yes, a standard pendant of old wired with 0,75 could feed a 100W lamp.

That's twice the load of a 50W halogen lamp,
And 0.75 has a maximum load of 6A.

 

[Taylortwocities]

One small point.
The round junction boxes are not really suitable for that application. That type of boxes are designed to be screwed to something and with the cables clipped. The boxes do not provide strain relief (eg clamps) for the cables.

This sort of thing is designed for the application. CLICK

 

[FrodoOne]

The rings are done in 1.5mm 3-core T&E and there are traditional round plastic junction boxes above each downlight.

A short length of cable runs from each JB to an individual downlight.

I am not certain as to how to interpret the word "cable" in this post - and the word "short".
If the "cable" is actually 1.5 mm2 "Building Wire", it should not be reduced in size (and can one obtain 0.75mm 3-core T&E?)
If it is actually 0.75 mm three wire "Flexible Cable" supplied as part of the fitting, that is another story.

One small point.
The round junction boxes are not really suitable for that application. That type of boxes are designed to be screwed to something and with the cables clipped. The boxes do not provide strain relief (eg clamps) for the cables.

This sort of thing is designed for the application. CLICK

The three wire version of this device may be suitable for this application. (https://www.screwfix.com/p/greenbrook-20a-way-lighting-connector-2-pack/2834r)

While I suspect that the "sockets" of these can be screwed in position, this is not clear from the "specifications"!


(Installation of one of the above devices on Lighting Circuits in ceiling spaces [in lieu of a BS 1363 socket] should make winston1 happy - or, at least, less miserable.)

 

[EFLImpudence]

1mm² is the smallest T&E.

You may notice that Two, Twin and Three all begin with T - so T&E obviously only means Twin&E - like RFC only means Ring FC; not Radial FC.

 

[winston1]

(Installation of one of the above devices on Lighting Circuits in ceiling spaces [in lieu of a BS 1363 socket] should make winston1 happy - or, at least, less miserable.)

BS 1363 sockets are not compliant in Spain. Most of this thread seems to be recommending UK parts and I’m not sure any of those are suitable for use in Spain. Nor do I know is Spanish sparks can “sign off” other people’s work.

 

[Taylortwocities]

BS 1363 sockets are not compliant in Spain. Most of this thread seems to be recommending UK parts and I’m not sure any of those are suitable for use in Spain. Nor do I know is Spanish sparks can “sign off” other people’s work.

I am mystified. Where did Spain appear?are you thinking of your holiday?
The OPs profile says Manchester.

 

[winston1]

I am mystified. Where did Spain appear?are you thinking of your holiday?
The OPs profile says Manchester.

Sorry, I was confusing it with another thread.

 

[Taylortwocities]

Thats brilliant. Your usual pointless addition to a thread.

Glad to see you are keeping up your average.

 

[winston1]

Thats brilliant. Your usual pointless addition to a thread.

That is all uncalled for. I admitted a mistake, why don’t you just accept it?

 

[gasket]

Thanks very much for the reassurance and tips guys.

All done. A short 1-foot length of 0.75mm 3-core heat resistant flexible cable connecting each 240v Ansell fire resistant downlight (with zone 2 type in bathrooms), fitted with 5w LED GU10 bulbs, back to the round plastic junction boxes on the lighting circuit (which is 1.5mm grey cable). There was already one junction box allocated per downlight when the house was built.

Each downlight is fitted an insulation support bridge to keep the fibreglass away.

Junction boxes have been secured and wire clipped into the ceiling joists before it reaches the downlight hole.

circuit is protected by a 6A Breaker.

really appreciate your help.

 

[SUNRAY]

That is all uncalled for. I admitted a mistake, why don’t you just accept it?

It almost hurts to post this comment, however I've been bleating on about you're errors/mistakes/silly or downright wrong comments and never admitting you're wrong. On this ocassion it's great to see your acceptance and apology and I really hope it's a turning point.

FWIW I have also managed to reply to the wrong thread a couple of times.