What's the correct way to solder twin and earth cable?

[Dave Plowman (News)]

Indeed - but you need a mechanically strong joint before soldering and twisting the conductor is a good way. And is not difficult to do as you suggested.

[clangers_snout]

Actually I wasn't really asking HOW to solder, or crimp, for that matter. I'm an electronics engineer so am quite competent at both. What I wanted to know was the approved, i.e. 17th edition, method of soldering T&E. I still don't know if I got an answer to that?

[Harry Bloomfield]

I agree that solder cannot tolerate movement, which was why I suggested binding them with wire rather than twisting.

Trying to twist a single solid core would harden the copper making the joint weaker, plus produces extra stress where the joint ends - than leaving the cores straight and over binding plus soldering. There was nothing dangerous in the advice, I have done it successfully many times and it is a standard method used for many decades.

In the 1960's there was an IEE regulation taught method of solder jointing the then used 7/.029 cable. It involved binding the two ends then tinning at two points along the length of the joint, rather than tinning the entire length. It was fairly similar to a splice in a rope. The point being to provide a joint which was not only sound, but had some built in flexibility.

[Harry Bloomfield]

Either a soldered or crimped joint would satisfy that requirement :-)

[John Rumm]

The 17th edition (or any previous for that matter) does not actually specify a method by which one should solder - only that it is an acceptable way of effecting a joint.

Hence it really comes down to good practice for good solder joints that may be subject to movement (thermal expansion, vibration etc). There are general requirements for cables being adequately sheathed (i.e. individual wires and overall sheath or other protection like conduit), and the use of suitable enclosures when individual insulated wires are otherwise exposed).

[Tim S]

John Rumm coughed up some electrons that declared:

When did wirenuts go out? I found some in formaer active use the other day...

[Andrew Gabriel]

I'm not aware of any connection boxes explicitly designed for soldering. Very few electricians are competent to solder, so there would be no market for them.

17th edition doesn't tell you how to solder, crimp, or braze connections. It's covered by requirement for good workmanship.

I will however comment on the special inaccessible connection terminals which have sprung up. They seem to me to be to be completely unsuitable for the job, indeed much worse than using screw terminals. It's as though the designer didn't understand _why_ inaccessible connections are specified to be handled differently, but just designed something which doesn't use screw terminals because he knew they aren't allowed. I've only seen pictures though, not had one in my hands.

[John Rumm]

Pass... well before my time!

[meow2222]

I'm a bit surprised that you can isolate the solder joint from all movement and force by binding it. It would need to be 30A fusewire rather than 5A, and presumably have a fair length of binding.

NT

[Dave Plowman (News)]

Tell the GPO that - twisted connections were the norm for many a year.

[Dave Plowman (News)]

Only problems I've ever seen with screw terminals on a domestic installation is where others have done them up - or rather not. I've never had any come loose or give problems so personally would be perfectly happy having an ordinary JB in a totally inaccessible place.

[<me9]

My parent&#39;s house was full of them dating from the 30s with lead sheathed cable. The most recent I&#39;ve seen was last year to connect the loopthrough in a ceiling rose installed about 1964. 13th edition I think.

[Andrew Gabriel]

They were never popular here for mains wiring (at least, when compared with US). I have a few UK wiring books going back to about 1930, and they aren&#39;t used during that period for mains. There is something which looks similar but actually contains a blind brass terminal with a grub screw in the side, and that seems to have been popular in that era. There&#39;s also something else today which looks similar and made me do a double-take on a couple of occasions, and that&#39;s a blind (one-sided) crimp.

They were popular for things like aerial, bell, speaker, etc connections, and you can still buy them for that sort of use.

Of course, you will sometimes find someone has put one on mains wiring. I moved into a house in 1986. It had been professionally rewired in 1974 to a good standard, but then less professionally modified in a couple of places, probably in 1984. After about a year, a socket in the kitchen stopped working. When I came to strip out the kitchen, I found that the neutral was connected to where the socket had been before moving it with a wirenut, which had burned out. So that was installed in about 1984, and looked new, but didn&#39;t conform. You will undoubtedly find such cases going all the way back to their invention, probably more so when regs were less strict, but they don&#39;t seem to have been in use for mains back to at least 1930.

[Dave Liquorice]

Can&#39;t say I&#39;ve been aware of plain twisted wires. Solder tag blocks, block terminals with screws, IDC, gel filled IDC "nuts".

Wire wrapping I guess but that didn&#39;t seem to last long or become widespread, I wonder why? B-)

[Frank Erskine]

On Tue, 12 May 2009 10:10:16 +0100 (BST), "Dave Liquorice" had this to say:

Twisted joints were in use by the GPO for _many_ years in underground cables - no doubt millions of such joints are still extant. Indeed, long before that, twisted joints in various forms (Britannia and copper-sleeve) were in use for overhead open wire spans. Considerably more skill (and time) is needed to perform a twisted joint than crimps and other &#39;modern&#39; types.

[Dave Plowman (News)]

Underground cable joints - twisted then paper sleeved before being sealed.