Best practice for this light?

[The Jeep]

I have just been asked to upgrade a Zone 2 bathroom light. I took the old one down to discover 5 grubby cables (loop in & out, switch, fan, mirror light, latter two from switched feed) all connected with plastic connector blocks and covered in tape. This arrangement was stuffed into a very small hole in the ceiling. It all looks v dodgy and I need to improve on this somewhat. In fact, the neutral from the mirror light was connected to the other cpcs with its own cpc disconnected!?!

Anyway, I'm thinking that a JB is required here, but there's not much room. Access from above has been ruled out. Any suggestions, guys? (I guess I could enlarge the hole in the ceiling and fit a small 4-terminal jb...).

(This domestic sparky malarky can be a pain - should've stayed on the rigs. At least the cabling was neat! ).

 

[JohnD]

Has the luminaire already been chosen? Some of the larger energy-saving ones may have room for you to put a block inside screwed to the upper casing (or at least make a big hole that the lamp body will hide)

 

[Spark123]

Could use a chock-box, you can push these up through the hole in the ceiling, (bit naughty I know) but to get at them for inspection and testing they can pull back through with the cable to the light.

 

[The Jeep]

Thanks guys.

The luminaire has been chosen and offers zero space between itself and the ceiling. Plenty of space inside, though, but it's not where you'd want to make connections to a bunch of cables, right next to the bulb!

Choc boxes are pretty small, as I recall, and there's not really room for terminating 5 T&Es. I'm thinking of some sort of JB that can be stuffed up inside, though. Needs must 'n' all that...at least I'd wire it correctly and it'd be a lot safer than the current dodgy arrangement!

Domestic wiring...it's pretty sad, isn't it?

 

[plugwash]

how big is the light? and how big is the current hole?

could you mount a 1G dryline box in the ceiling such that the light will cover it when fitted and make the connections there?

 

[The Jeep]

That's a possibility, captain....thanks, will investigate this afternoon.

 

[securespark]

However, you have to think about heat rising: how close is the lamp to the ceiling?

 

[The Jeep]

I've just installed a nice wee jb in the ceiling, with all the wires now neatly connected therein and mounted the light directly below it. The light is fairly flush with the ceiling (1/8-inch gap?) but has a heat deflector/reflector fitted behind the bulb.
Do you really think there might be a problem with heat? I thought this for a mo, then discounted it as light is designed to go on ceiling so this should be taken into account in the design (?). Admitedly, the jb is directly above...hmmm, I hope this ain't a problem...

 

[securespark]

Only a temp probe in ceiling would tell you!

 

[JohnD]

energy saving lamp would run a lot cooler

 

[The Jeep]

Thanks, guys. Yes, it is difficult to tell what the temperate is above the light. Perhaps max-temp recording stick-on indicator label?
However, I feel that, as this luminaire is designed to fit directly to a ceiling, which could be made of combustible material (wood, hardboard, polystyrene(!)), they shouldn't transmit too much heat upwards, what d'you reckon?
There is a small air gap then my JB which is one of the brown 'bakelite' type: surely these are reasonably heat resistant? At the very least it's a heck of a lot better than it was before!
Thanks, also, for the suggestion of low-energy bulb: will look into that.

 

[securespark]

Only if the fitting is F marked should it be fixed to a combustible surface. Is it?

 

[The Jeep]

That's news to me securespark...am not aware of the F mark. F word, yes, but...
I'm going to make a temperature check above the light. I may reposition the light, too, so the hotspot is not below the jb.
The ceiling is plastered with just the hole for my jb, which is not actually touching the fitting. There is probably 75% contact with the plaster. May end up lifting floorboards yet, but i hope not!

 

[securespark]

Thought you said access from above ruled out??

F marking is where luminaires suitable for mounting onto a combustible surface are marked with an "F" in a triangle. If your fitting does not have one, or has one with a line through it, it is not suited to such a location.

What is the ceiling made of, and is your fitting marked?

 

[The Jeep]

Sorry for the contradiction, securespark: access from above is a major headache. Possible but much hassle.
The ceiling is plaster, the luminaire is a metal-cased IP44 with 60W bulb. The JB is thermosetting urea (I spoke to the manufacturer). It will take a lot of heat. In fact the PVC sheathing on the wires would melt first.
But think about the physics: the hottest anything can get from direct contact with a bulb is the temperature of the bulb itself: enough to melt some plastics and possibly ignite certain combustible materials. However, if that bulb has a metal heat deflector between itself and the metal housing of the light unit, which is also acting as a large heat-sink, the amount of heat transferred upwards through a 1/4-1/2-inch or so air gap to a thermosetting plastic jb is not going to be very great.
When I go back tomorrow I'll leave the light on for a while and feel to see if the metal housing is getting warm. Because it's such a large piece of metal (30cm dia), the heat transfer should be quite uniform, so I'll have an idea of the temperature at the centre. I'll probably stick in a low energy bulb, too. Cheers for your help and feel free to contradict me!