Hi all,
I'm re-routing a ring main that was in my stud partition, through my plasterboard ceiling. I'm joining up the ends with a junction box. Is it regs-compliant to leave the junction box "loose" in the ceiling, or do I have to screw it into the concrete?
Antony
I believe only for fire alarms and other critical systems such as emergency lighting.
ceiling, or
Err, this sounds like there is a concrete ceiling and a plaster board sub ceiling, how is the OP going to leave the junction box serviceable ?
Is there access to the junction box once the work is complete? If not it fails on that score fixed or not.
This is a pain as I thought things were going well and I was getting quite impressed with myself. I don't want to come across as an idiot, but Collins doesn't seem to mention this. I don't see how it is ever possible to leave access to a junction box (although obviously it is otherwise nobody would have them). Most people I know don't have access panels in their walls and ceiling. I live in a flat so have no access from above, and the sub-ceiling is concrete even if I did. This also scuppers my plan to add new ceiling lights using junction boxes. If anyone has suggestions about how I could deal with this, I'd be grateful. So far, my proposed uses for junction boxes are:
For (3), can I use chocolate block in the back boxes of the existing and new sockets to extend the ring? Presumably it needs to be wrapped in insulation tape as the box is earthed? If this is allowed, then it's actually a better solution than what I originally proposed, as there is no need to chisel a hole in the wall for the junction box.
Antony
Ok - might have helped myself here. Reading the archives, Andrew has posted that he soldered junction box connections where the box would be inaccessible. Is this regs-compliant? And what sort of wattage soldering iron would I need? The only one I have now is a Antex 18W.
Antony
At the risk of ruining this thread - after further research I've decided that crimping / heatshrink sleeving is the way forward for (2) and (3).
However for (1) I might still use a junction box and solder. I have six light fittings which I'm arranging in three rows of two.
Reason 1: The existing circuit cable (which I will break into for each pair) is running down between the pairs. Reason 2: The smallest hole that I can fit a junction box through would be too large not to appear beyond the base of the (small) fitting, so I can't put the box up above where the fitting goes, which is the only way that it could be accessible after all is made good.
Antony
You will need something a lot better than 18W, at least 50-80W and with good heat capacity ie the ability to supply a good quantity of heat without going cold. Remember, you have a lot of metal to keep up to temp.
Dave
Useless. That's for electronic work.
Best thing would be one of those 'instant' heat solder guns. They are 150 watts. Seen them in B&Q etc.
Fit a BESA box (two inch round box) into the plasterboard - you can get dry-lining versions - and mount the light on that.
You can use solder or crimp connections; these do not have to remain 'accessible'. Alternatively one of the aforementioned BESA boxes flush in the plasterboard with a blanking plate is fairly inconspicuous after a couple of coats of paint.
Yes
The insulation around the chocolate block should be adequate, provided there is enough space.
Owain
It's a win all round to do the cable joining only in the backboxes, where possible - saves you/future occupant hunting for the junction boxes when repairing or extending.
As Owain says, you don't need insulting tape round the chockenblocken - they provide adequate insulation in their own construction, and the adhseive on tape usually goos out over the years, making a Mess. One thing which can help - depending on house construction - is to replace your existing backboxes with deeper ones. (There are 3 generally-available depths: a plaster-depth one (about 12mm/half inch) - mainly for lightswitches, which are shallow, and block or brick construction with a thickish plaster skim keeps the whole of the box under plaster; the 'normal' 25mm/1inch you'll see with most 13A sockets, FCUs, and friends; and a 38mm/inch-n-half depth, classically used for cooker control units, 45A switches, and other heftier gear with heftier cables. If you can make room for a 38mm in place of the existing 25mm, you'll have more room to work.
Then you can fill that room either with chocblocks as you suggest, or by taking two spurs off the back of one socket. Provided the two spurs won't both be likely to be heavily loaded (and the socket terminals are big enough to take 4 conductors and make good contact among all of them: MK, Crabtree should be fine here, pound-shop-special-pack-of-three not!) this is quite permissible. Where all the sockets are in the same room - even more so if they're on the same stretch of wall - it's most unlikely that there'll be an excessive point load on the ring.
It's also possible to keep things on the ring by using two singles side-by-side in a dual, as opposed to double, mounting box.[1] One original cable runs to the LH single, new cable to new socket, new cable from there direct to second new socket, new cable back to RH single, original cable joins at that RH single. Presto, all on ring, no more than two cables in any one socket. (Not my idea, this - suggested on this group a coupla weeks ago, too useful not to pass on ;-) Or you could do 'half' of this with only 1 choccie block - keep 1 original cable in original socket, go out to your two new ones from there (i.e. existing-socket-to-new-socket-1, on from there to new-socket-2), and bring back a new link to the existing socket position and join to the other existing ring cable in chocblock.
[1] Can't say I've ever seen a 38mm dual box, mind, though they probably do exist! You won't need one, though, under this proposal. Downside is you still have to do a little expansion of the existing mounting hole - instead of making it 12mm deeper, which ranges from a PITA in brick to a total non-issue for wing-mounted plasterboard boxes, you need to extend sideways by a bit under 1cm, since two singles are wider than one double.HTH - Stefek
Why use a junction box at all? Cable is cheap.
FYI, and in the best tradition of Usenet pedantry, the depth of the standard 'plaster depth' box is 16 mm, and the standard depth you refer to as 38 mm is in fact 35 mm. Cooker switches and the like, where 6 or
10 mm^2 cables are expected normally require an extra deep box - 47 mm.
Try MK list no. 887 ZIC. Interestingly, that's the only depth MK do for that type of box.
Junction boxes and ceiling roses have the appropriate terminals for the circuit, light, and switch, a BESA box clearly doesn't. I thought about a 4-row chunk of chocolate block (mmm tasty!).
Antony
That's fine inside a BESA box.
That's exactly what you use - except you may find that you can connect Switched Live and the Neutrals at the luminaire, (and possibly the Earth) leaving only the Lives on a chocblock.
Owain
Coo! They say you learn something every day: here we are, not even lunchtime yet, and I've learnt *two* ;-)
Ta - Stefek
I've been drawing some pictures and this looks neat. One question - if my diagrams are accurate (and let's hope they are), I need two rows of choc per luminaire (one always hot, one switched). I'm connecting three lights, to be controlled by a 3 gang switch (it's actually six lights but I'm daisy-chaining one off each).
It seems that to carry the permanent live forward, I need to connect the choc between the lights - but it also seems that I could make that connection at the switch. Am I correct and does it matter which I choose?
Antony
If all the lights are on the same circuit (fuse/MCB) you only need to take 1 permanent live from the lighting circuit to the switch, and common it across the three switches, and then three switched-lives back. Then take a switched+neutral to each light. Assuming you are looping in at one of the lamp locations (lamp 1a), that gives you
Loop-in Live ) Loop-out Live ) Live to Switch )
Switched 1 ) Sw L to Lamp 1a (bulb)) Sw L to Lamp 1b )
Switched 2 ) Sw L to Lamp 2a )------Lamp 2a----Lamp2b
Switched 3 ) Sw L to Lamp 3a )------Lamp 3a----Lamp3b
Loop-in Neutral ) Loop-out Neutral ) Neutral to Lamp 1a (bulb)) Neutral to Lamps 2 ) Neutral to Lamps 3 )
Earths for 2 loops, switch feeds, 3 lamps )
I make that 6 connectors at the main lamp location. At the distant lamp location you just need Sw L, N and E. You do not carry the permanent live on to the distant lamps.
You can run two twin-and-earths to the bank of switches provided you run them close together (as the live will be going down one cable and the switched live returning up the other cable)
LABEL the figgin' CABLES AS YOU PUT THEM IN!!!
Owain
I find no problems making joints in 2.5mm t+e with a 25W iron. You just have to let it heat up again before making the next joint.
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