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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..
I have a couple of junction boxes in a ring main circuit with spurs off,
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?
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
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Thanks Andrew, I am pretty good at soldering so it should not be a problem.
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.
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.
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:
(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.
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.
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?
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
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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