Crimp joints - Yes or No?

[Handyman]

I have asked this question before, but seem to be unable to get a definitive answer:
"Are crimped joints acceptable to extend domestic circuit wiring into a new Consumer Unit, and are crimped joints within IEE regs?"

What is the definitive answer?

(Assume, for the purpose of the exercise, that crimps are the insulated variety, of the correct size for the cable in question, and joints are assembled correctly with a ratchet crimping tool)

 

[LifesABitchAndThenYouFry]

IEE Regs don't specificaly mention crimps - don't say you can - don't say you can't - therefore short of writing to IEE I doubt you will get the definitive answer. The concensus is that you can use them but they must be current rated for the application and be housed in a Junction box.

 

[Handyman]

It's the junction box requirement that'll cause me grief. I've got about 24 wires coming in, some of which are just too short to reach new CU. If I use junction boxes, there just isn't enough room to mount 18 or so JBs. Hence, crimps would save the day (and space).

 

[ban-all-sheds]

I know that the ratchet tool is different from the normal squeeze-and-hope crimper, but are the crimps themselves that are meant to be used any different from these:

Having used those, I can't see how a different tool would alter the fact that they are cr@p.

I understand the general downer on the use of junction boxes instead of replacing cables, particularly when they end up in a rats nest under the floorboards, but there are times when practicalities mean that cables have to be joined, and extending them when moving a CU seems to be a common requirement.

What I don't understand is what appears to be the deprecation of screw-terminal based methods in general. Screw connections seem to be acceptable for meter tails, MCBs, the terminals in wiring accessories, so why not as a means of joining cables?

Maybe JBs with this type of terminal in them are not mechanically ideal:

but what about these types?

The second one particularly looks like it could achieve a very sound connection.

Also, you can get DIN rail mounted terminals with screw connectors which have a plate which bears down on the conductor, rather than the end of the screw, they tend to be designed for one particular conductor size, up to quite large, and are rated for the currents applicable to the conductor size. Wouldn't they be acceptable for extending cables? From Handyman's POV, they are compact enough for his requirement, and they could all be tidied away inside a box mounted on the wall.

 

[Handyman]

Yes, proposed crimp joints are as depicted. I was hoping that IEE regs and/or expert leccies might help with a definitive answer, but clearly this isn't the case.

I've considered all these other options, Ban, but this doesn't avoid the problem of 18+ round/oval junction boxes all over my wall. What might be a good alternative is, if it's possible to get a sort of mini-consumer unit which simply has a long row of connectors on a rail with a plastic cover over the top (like mcb's but without the cb's ). This could be mounted close to the ceiling and accept all ring tails, etc., then I could extend from these connectors into the new consumer unit(s). This would be a neat and safer (although more expensive) solution. And it would also hold all the wires neatly in place. Do these things exist? And if so, where?

I have to say that I am concerned about crimp joints and would prefer nice screwy ones. I have this fear of a badly-made crimp joint starting to zizz as the current demand increases.

What I find strange is that no one else seems to have had this "short tail" problem to any degree. I would have thought that resiting CUs was a fairly common job.

 

[yankey-sparky]

Don't you use wirenuts in the UK? I've never heard them mentioned even once on this forum, and they're all over the place in US installations.

 

[ban-all-sheds]

... What might be a good alternative is, if it's possible to get a sort of mini-consumer unit which simply has a long row of connectors on a rail with a plastic cover over the top (like mcb's but without the cb's ).

Something like this you mean?

Go to the RS website, and do a couple of searches on 'din' and 'rail' (don't know why just the one doesn't return all the products) - you'll find all sorts of items, including a variety of connectors like these.

They also sell boxes with DIN rail in them:

but they're a tad pricey what with those hinged covers. It shouldn't be rocket science to buy a strip of rail and fix it inside the box of your choice - TLC do a range of reasonably attractive ones (i.e. about as pretty as a CU):

 

[Handyman]

Good stuff, Ban. I'll check this lot out. Thanks.

Still surprises me no one else has had similar problem, though.

 

[securespark]

yankey sparky

Used to see wirenuts ocassionally still do but mostly from lighting dating back to 1960's. Don't see them so much now.

Twisting wires together is considered BAD!!!!!!!!!!!

Sometimes they snap.

 

[amtodd]

In a different thread amtodd wrote:

You will need butt crimps. This is not something which Yankee-Sparkey will use for his nocturnal activities, but what you need to joint your cables. Spade/ ring terminals etc may be suitable for cars, speaker connections and inside exquipment, but if you use them for your wiring, I suggest a new forum may be required for DIY coffins.

You can find butt crimps at Screwfix, RS and many other suppliers. There are different sizes for different cable diameters.

• 
  Do use the correct size as you will not get a good joint otherwise.
  Do use a proper tool such as these and not the type sold with kits intended for cars (Even B&Q sell reasonable ones for £20 inc vat these days).
  Do not use them to joint more cables than they were designed for. (butt connections designed for two cores to be joined).
  Do not use them on ELV kit as they do not take to temperature as well as the silicon cable many ELV lamps have.
  Do stagger the joints where possible.
  Do strip off the minimum amount of insulation possible so that there is a firm joint, but there is no bare copper showing.
  Do ensure your joints are properly contained inside conduit, trunking or some kind of suitable box.

 

[ban-all-sheds]

RS sell a range which have quite a long overlap of heat-shrink insulation integral to the crimps:

They're made by Raychem, so no doubt available from other fine suppliers.