Hello all
I have just had my kitchen drylined and now the cables entering the backboxes are too short to be easily wired into the socket/light switches. I'd like to just extend the cables with a chocolate box connector (I think thats what they're called!)My question is what type do I need, I see 30AMP big ones and other smaller ones. whats the smallest connector I can get away with, is it dependent on the ampage of the connected device?
Cheers
Richy
you CAN extend them by any means practicable (but you should use proper mains connector blocks which won't fit in the space available) which may in the long run give problems and danger, but the correct and safest fix is to rewire or pull through some slack.
mrcheerful
Personally I'd use either crimp splices or soldered joints, covered with a couple of layers of heatshrink. If using crimps it is absolutely essential to use a proper ratchet crimp tool, not the cheapo plier types.
couple of layers of
ratchet crimp tool, not the
I'm a big fan of soldered joints too for this kind of thing, but only where I know the load is low. It is very hard to really define what power the soldered joint will be good for.
>
Might be easy to fit extra deep boxes - 47mm - if the walls have been dry lined?
"Dave Plowman (News)" wrote | > you CAN extend them by any means practicable (but you should use | > proper mains connector blocks which won't fit in the space | > available) | Might be easy to fit extra deep boxes - 47mm - if the walls have | been dry lined?
Especially as, to keep the sockets on the ring, two lots of connectors will be needed. Using one connector on the circuit cables and then single tails to the socket turns the socket into an unfused spur.
Owain
Thanks for your reply:
How big are these, do yo mean the big 30AMP connectors? The problem I have is that the back boxes are recessed into the brick wall, I dont have the option of fitting other deeper backboxes, pulling any slack cable through or running any new cable. The wall is not a stud wall and getting access under the floorboards and attempting to run new cable would be virtually impossible as the plaster board has been dab and dobbed (whatever you call it) Also I haven't a clue what a crimper is and how I use one.
Thanks!
Richard
Soldered joints, like crimps, depend a lot on how well they are done. A good solder/crimp is pretty much as good as the wire itself. A bad one is way worse than choc-bloc!
On Sat, 18 Dec 2004 14:01:49 -0000, "Owain" strung together this:
Which isn't a problem.
Isn't there a restriction on the number of spurs from a ring?
Sorry to interrupt, but can I just make sure I have this clear?
As long as I don't exceed the permitted number of spurs, I can fit a junction box into a ring circuit and take two separate single cables from it to two separate double-sockets, and this counts as two individual spurs?
Bert
It should be possible to remove the old boxes from the brick wall with a bit of care - run an old chisel between the box and plaster, but not down the side where the cables enter. Then use some pliers to ease it out. Of course remove any fixing screws first. ;-)
Junction boxes are not really allowed on a final ring mains circuit. A ring mains is rated, usually, at 32 Amps total running load, so a junction box with terminals rated at this loading current are pretty big things. You are allowed one fused spur from each socket on a final ring mains circuit if you wish. To take a single cable to supply two individual double sockets that have a total loading capability of 4 X 13 Amps = 52 Amps where the diversity rule doesn't apply, isn't allowed.
Yes. It's certainly permitted. And a 30A junction box will allow all 4 cables to be connected pretty securely, though it's a tad tight.
Whether it's actually *smart* to run with spurs is another matter; once you're breaking into the ring, it can be as easy to extend the ring as to spur. If it's to supply an occasional-use socket somewhere in a corridor or storage-only loft, a spur is the right answer almost always; if it's to supply a double socket in a room which may end up as the place a whole load of kit gets plugged in, I'd go the extra mile and put them on the ring.
Stefek
Stefek,
A good point, though this would involve using two junction boxes rather than one. I'd have thought there's less disruption to the circuit, and therefore less vulnerability, in using a single box with two separate cables coming from it. I won't even have to cut the ring circuit: I can just bare and strip the wires and lay them across the terminals (though I 'll have to cut the earth to fit the sleeving, I suppose).
That is the case in this instance, except that two separate sockets are involved. Neither would be subjected to anything other than very occasional use.
Thanks for the reply.
Bert
How is a junction box, of the correct rating, any different to a socket ?
A ring
Yes, but so are the terminal in the back of sockets.
The only problem with junction boxes is that many get placed in locations that are not *readily* accessible.
Often that's the case; but when I've done ring extenstions, I've nearly always made at least one end of the new bit of ring replace an existing shorter leg, running from an existing socket - if you see wot I mean. For example, imagine there's a ring cable running between sockets in bed2 & bed3: to add a socket on the corridor outside the two bedrooms I'd lift boards in the more accessible bedroom, run a new length of cable from the socket there to the new socket, and use the existing cable from the other bedroom - possibly shortened - to complete the ring at the new socket.
But this is effectively irrelevant to what you're doing ;-)
Yes, many people like to keep the integrity of the "main" ring cable this way. "Pro" sparkies (for whom time-to-complete is a driving issue) will rarely bother, and are less likely to be wimpy about tightening the terminals in any fitting ;-)
Then I'd have no qualms in running with the single JB approach; remember to leave the JB nominally "accessible", i.e. if under floorboards, mark the location and replace boards with screw-not-nails; if in some other void, provide some form of maintenance access.
Stefek
Yeah but no but yeah but no but no, actually.
Adequately-rated JBs are perfectly allowable on ring circuits, and available from all the usual suppliers in not-particularly-monstrous sizes. Larger than yer 20A lighting JBs, but not vastly more (half-as-big-again in diameter is typical, with MK doing a more robust-looking rectangular one. Or at least they used to!)
Yes, there's guidance to restrict the number of spurred sockets-n-FCUs to no more than the number of non-spurred-sockets-n-FCUs; it's not a strict engineering limit (as in, house will catch fire if one more spur added), rather a guideline to keep rings basically as rings, rather than silly pseudo-rings with a positively daft number of spurred-off accessories. In a domestic setting, the odd spur or two can make perfect sense; in a commercial/industrial one, where loading of individual points is much harder to anticipate, spurs are much less likely to be a Good Idea.
As for "double socket = 26A" (even if you incant away diversity) - it would be a most unusual situation in which 26A were really drawn, and AFAIK even the best manufacturers design their doubles with the assumption of no more than 20A loading. The point you make about a single cable running to two separate sockets is quite correct: the reasoning for it is more clearly demonstrated when they're double sockets, but though there used to be a 'concession' to say 'well, two separate *singles* can go on one unfused spur run', that notion dies a death in the ?15th? Edition, presumably (a) because the single could readily be changed to a double later on, (b) it meant "two cables running to this socket so it must be on the ring" was untrue.
Stefek,
Thanks for the reply.
Though I know this is recommended (and I will do it) I do wonder exactly why. Apart from a total rewiring job, the only reason I can think of for ever needing to get to the junction box again would be if the terminals needed to be re-tightened. Is this likely? And in any case, how would I know that it needed to be done? Are there recognisable symptoms?
Bert
The fresh scent of ozone, maybe a little carbonising ;-) The refinement-in-practice of the "good workmanship" principle of the Regs is that all "non-permanent" joints ought to be accessible, for testing and repair. In particular, testing of the integrity of a ring (making sure that it still is one every few years!) is when you want the accessibility - to be more specific, it's when you find anomalous results from such testing that you want to get at successive points on the ring, and since problems at connection points totally dominate the likely faults (not that many titanium-toothed rats around ;-) that's the reason for keeping all connection points accessessabubble.
In practice, if you do the connections up sensibly tight in the first place, and avoid silly squashing and overtight bending of the conductors (and any repeated movement of the cables, naturally), your screwed connections will be find for 40 years or more...
Stefek
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