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

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I need to join some T&E cable that will be inaccessible and I don't want to use maintenance free junction boxes, so what is the approved way to solder and sleeve T&E cable?
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In an earlier contribution to this discussion,

Probably better to crimp them - as explained in the DIY Wiki.
http://wiki.diyfaq.org.uk/index.php?title Κble_crimping
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Cheers,
Roger
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In article < snipped-for-privacy@e23g2000vbe.googlegroup

If your having to ask that.. Don't do it .. crimp it, I would anyday over solder much less fuss and a better joint and self insulating:>...
But make sure to get a decent set of RATCHET crimp pliers not the cheap 'n useless ones..
--
Tony Sayer



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scribeth thus

which apparently don't comply with the latest regs, is it OK to replace these with crimped connectors, and if so, what size connectors would be needed for the extra cores of the spur. If this is not OK, would it be OK to neatly solder the joints, and then lay them in the junction box as before, using the original screws to hold the now soldered joints in place?
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Why? Is it because they are inaccessible for testing/inspection?

There isn't any general requirement to bring such items up to current regs, as long as they conform with the regs in place at the time they were installed. Having said that, I think you have to go back before 16th edition before that conformed, and this is something I would bring to current standards.
Secondly, unless you are already very experienced at electrical soldering, I would suggest using crimps. Crimping is likely to produce a more reliable result in less experienced hands, providing you are using a proper ratchet crimper and do a few practice goes first on offcuts, and make sure you can't pull them apart and the conductor is clamped firmly.
If you are _very_ experienced at electrical soldering, then a way to do this is to use a standard screw terminal junction box as normal, and afterwards solder each terminal and its conductors together. This is not trivial because the T&E insulation won't stand soldering temperatures with any stress on it, such as bends near the terminal, or pressing on anything (other wires, box edge). Also you'll need a powerful iron (50W absolute min) or you'll take too long heating the metal and cause too much damage to the insulation. Make sure the box itself is made of thermosetting plastic (non-melting) -- the circular ones are normally OK.
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Andrew Gabriel
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writes:

I had thought of binding the cores with 5A fuse wire before soldering, the cores should then fit in the terminal box OK, and could be also screwed, a bit like a belt and braces approach, but when I got the soldering iron out to do it, I realised that I had turned the power off and hadn't got any power to do the soldering, so it was placed on the to do list :-) I will have to run an extension from the garage to get it soldered, before nailing down the floorboards.
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Harry Stottle coughed up some electrons that declared:

Looks kosher enough.
The trick is to give the wires a bloody good pull after crimping. If they don;t come out you're winning.
Good insulated crimpers will give you a double crimp on each go - that's something to check for too.
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Harry Stottle wrote:

Crimps will join 2 cables end to end without any overlap, they aren't suited to adding a branch.
--
Mike Clarke

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clangers snipped-for-privacy@yahoo.co.uk wrote:

You need some heatshrink in a couple of sizes (about 12mm does the overall sheath). Strip the wires - about 15mm ought to do it. Slide a smaller heatshrink onto the L & N wires, and the larger one onto one of the cables. Twist the ends together tightly inline - much of the mechanical strength of the joint will come from the twisting - you don't want to rely just on the solder. You then want an iron with a decent sized tip and heat capacity. Using a flux cored electronics solder, tin the tip, apply the iron to the joint, wait, then apply solder to the joint and allow it to flow into it. Remove the solder and then the heat. Allow to cool before moving. Repeat for the other wires.
Now using a multimeter on a low ohms range, test the joint quality from the next adjacent test points (i.e. sockets either side in the ring). Disconnect the repaired wires at both ends from the circuit, and at one and twist together all three wires, then measure the resistance between L&N, and L&E at the other position.
Compare your results with the expected values shown here:
http://wiki.diyfaq.org.uk/index.php?title=Electrical_Circuit_Faults#Wire_resistance_table
(you will need to estimate the length of the cable you are testing)
If all is well, heatshrink it up. And wire the cable back into circuit.
Don't underestimate the importance of testing - one dry joint could cause significant localised heating of the cable.
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Cheers,

John.

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John Rumm laid this down on his screen :

Rather than try to twist them together, which with 2.5mm will be difficult, overlap the two ends then bind with some small diameter copper wire (30amp fuse wire?), then solder. I would also suggest offsetting the three joints so they don't all occur at the same place so the bulk is reduced.
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Regards,
Harry (M1BYT) (L)
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Harry Bloomfield wrote:

With a couple of pairs of pliers, twisting 2.5mm^2 inline is actually quite doable - just make sure you start with enough length of wire.

Yup, staggering the joints helps.
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Cheers,

John.

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Eh? Dead easy with ordinary combination pliers.
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*Frankly, scallop, I don\'t give a clam

Dave Plowman snipped-for-privacy@davenoise.co.uk London SW
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On Sun, 10 May 2009 23:30:22 +0100, "Dave Plowman (News)"

But the OP was asking about _soldering_ :-)
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Frank Erskine

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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.
--
*24 hours in a day ... 24 beers in a case ... coincidence? *

Dave Plowman snipped-for-privacy@davenoise.co.uk London SW
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Frank Erskine wrote:

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?
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clangers snipped-for-privacy@yahoo.co.uk explained :

Either a soldered or crimped joint would satisfy that requirement :-)
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Regards,
Harry (M1BYT) (L)
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clangers snipped-for-privacy@yahoo.co.uk wrote:

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).
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Cheers,

John.

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John Rumm coughed up some electrons that declared:

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

Pass... well before my time!
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Cheers,

John.

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On 11 May,

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