While agreeing with all of Andrew's caveats, I'd add that you can adapt a trick from electronics and use a pair of thin-nosed pliers on the wire to act as a heat sink. In this case you're going to end up with two pairs of pliers and the iron and the solder all to go in, so unless you are an octopus you are going to need a friend, or some haemostatic forceps.
I'm really, really sorry if I come across as labouring this point, but I need some definitive advice on the best way of connecting two pieces of ring-main T&E together.
Regular readers will know that I started off doing this with terminal blocks but because these would have to be hidden behind plasterboard, either soldering or crimping was the only way forward.
I chose soldering. I understand there are a couple of gotchs when doing this:
- each join must be soldered ASAP because the PCV coating on the T&E will start to melt; this can be a problem if there is a bend in the wire near the soldering because the copper can "push through" the softened PVC so it touches its neighbour
- bind the cables together to form a strong mechanical joint before soldering; keep the solder light to merely enforce the joint.
With that in mind, this is what I did:
- twisted the cables together using pliers
- tinned the soldering iron
- heated the joint and flowed solder onto it
I used a gas-powered soldering iron because, obviously, the power was turned off.
The joints I made seemed strong but didn't occur in just a few seconds - in some cases I had to heat the joint maybe 30 seconds or more before it became hot enough for the solder to melt onto it.
I didn't notice the PVC becoming damaged, either expanding or melting. It seemed to me to be as good as before. I'm just a little worried that it might have melted and become compromised above/below the joint, where I can't see. On the other hand, I've tested the sockets with devices that draw large currents - if anything had gone wrong, I'd know about it, wouldn't I?
Secondly, I wrapped the joints in electrical tape because I just couldn't source heat shrink in time. Each joint was wrapped 3 or 4 times, and then the whole thing was wrapped in more tape.
I *think* I've done this well enough. One final thing I might do is put the joints inside fireproof boxes so that in the unlikely event of something going wrong, they won't set the house on fire.
I would strongly suggest crimping unless you are already expert at electrical soldering (in which case you wouldn't have posted this question). Crimping is much easier to get right and reliable (in spite of the unjustified scare storey floating around here) starting from an untrained position on either side and it is standard electrical practice, whereas soldering isn't. Use insulated crimps and a proper ratchet crimper, and do some practice runs.
When I solder connections, I use a regular junction box in the normal way to provide the enclosure and mechanical support just it would normally be used, and then solder the terminal connections and conductors together additionally afterwards. However, this can't be said to be standard practice, because as I said before, soldering isn't standard practice (although it is permitted) -- electricians are not taught how to do it.
If you're asking someone here to tell you it's OK, no one can, because no one saw you making the connection or inspected the quality of it afterwards. If you are unsure, get an electrician in to inspect it and possibly redo it and test the integrity of the ring circuit.
How would he/she go about testing the integrity of the circuit? Do you mean continuity?
Just how big (or small) is this gas iron. Having done electical soldering many years ago, if it didn't work in a couple of seconds and run the solder over the joint, I would have given up. For 13A cable a 50W electric iron with a fairly heavy 1cm diam bit minimum is needed, preferably 1.5 cm. A 15W electronic iron would be far too small and its small heat capacity would mean the wires cooled the bit to below solder melting point, which is what seems to be happening.
rusty
I would second that - much easier and reliable
Mike
There's a standard way to test the integrity of a ring circuit (a google search of this newsgroup will turn it up, or you can find it in the On-Site Guide or the Inspection and Testing notes book to supplement the Wiring Regs). Basically, the resistance of the live and neutral loops are checked to be the same, and the CPC to be as expected, and a check for cross-connected ring is performed. The resistance is ideally measured using a high current low voltage source, to tease out bad connections (which a bog standard multimeter can easily miss).
In article , Brian writes
Sounds good.
Do you only have one ring?, handy to have 2 for just such an occasion as this, also this would be on of the few acceptable situations to use an electric iron wired up to a lighting circuit adaptor.
Ok, 30s is way too long, if you haven't made the joint in 5s then your iron isn't powerful enough and you risk overcooking the joint/insulation. The irons I would use for something like this are 60 or 45w temperature controlled irons fitted with a large tip but I could probably make the joint adequately with as standard (cheapie) 25W item. As wire is cheap you can practice making these joints all day until you've got it right, then move over and do it on the critical joint.
The problem with overcooking the work is less likely to be in the current carrying capacity of the joint but in the integrity of the insulation which may break down after a few years of ageing, not something you would want to have buried in the wall.
Not really a good plan as insulation tape ages, its adhesive fails and the wrap loosens, not the best for the long term. That said, many hundreds of thousands of houses in the uk have hidden chocolate block joints (sometimes) wrapped in insulation tape which have not caused problems. It just seems a shame to start doing the best possible job you can, then skimp on the details. Personally I use adhesive lined heatshrink on all my joints, that way it stays where it is put and offers additional strain relief.
Nope, if you aren't confident in the job, use a 'pro', HA! there's a laugh, 4/5 would probably twist the wires, wrap it in insulation tape & bury it ;-)
As other have said, no-one can say authoritatively that your joint is good so it may be worthwhile remaking it after a bit of soldering practice and using the right sort of insulation.
Btw, my preference is still for soldering over crimping, I've seen too many badly made joints caused by operator error in choice of crimp and/or tool setting just waiting for long term failure but that's just my experience.
I'm sure this sounds like a lecture, its not meant to, good luck :-)
Two risks on the critical path... o Connection
---- failure can cause local-heating or MCB/RCD trip
---- failure on a ring is 1) not obvious & 2) can result in 2.5T&E carrying 32A o Insulation
---- failure can cause local-heating or MCB/RCD trip
---- failure can cause a N to E link, triping RCD & non-isolatable by MCB
Soldering involves both soldering & insulating tape risk. o Tape seems to unwind -- not convinced about decadal cold-flow o Soldering requires speed -- PVC insulation *continuous* rating of 60oC
Crimping involves single ratchet tool risk (insulating crimps proven). o Crimping practice -- pull-apart test & inspect insulation
Surprised there isn't a simple kit... o Simple barrel crimps tightly matched to solid core o.d. intervals o Micro LNE-divided housing + bit of pourable epoxy, velcro for the cat
You can get heatshrink-insulating-crimps re extra mechanical strength. Do not consider using cheap-n-cheesy stamped-bar crimp tools.
I originally heard this back when I was in short trousers and dropping solder on my legs in the late 60's and had my doubts it did any good as designs using fragile germanium devices were soldered ok.
Progressing onto circuit design, development, and repair of industrial control and communications equipment from the late 70's to the mid
90's I, along with all my colleagues, never saw ANY advantage in using a heat shunt - fast and quick with, if necessary post transition rapid cooling is the way to go - a heat shunt always, without exception, slows down the process and increases the heat input from the iron that is required to get the joint and solder up to flow temperature. Apply it after the solder has flowed and there may be some slight advantage but a slight wait for the transition followed by freezer spray does just a good if not a better job and can be applied much quicker than a heat shunt.We regularly soldered the smallest leaded components with temperature controlled 50W soldering irons, even a tiny 2.5mm x 1 mm detector diode in a spectrum analyser costing 350 quid was soldered like this (albeit with a nervous hand). Later on surface mount components were done this way until we got our infra red rework unit and hot air reflow guns. Our repairs were tracked for many years (certainly to my knowledge until post 2002) and failure rates post repair were extremely low.
Not forgetting an insulation resistance test (high voltage) which might be more illuminating in this case as the OP is worried he might have damaged the insulation, or that his tape-wrapped joints are not good enough.
Hwyl!
M.
Ok - you lost me on the last claws - ???
Geo
No, just one ring. I don't have friendly neighbours. A 50W iron would (according to my calcs) require an extension cable of handling around 5 amps. I don't have one of these.
Well, it's done and, if what you say is true, I'm well and truly f***ed. The joints have been made and if the insulation has been damaged then it's damaged forever. It's hard to describe the situation but the solder joints were made just after the T&E comes out of a concrete-cladded wall. In other words, I can't cut back and start further up.
Tell me truthfully - is this something that *really* happens in real life? I'm not being trite - I really want to know. Does anybody have any actual experience of it happening?
I've got some small experience of soldering and consulted a pal, and I'm sure that the joints are good enough, both mechanically and in terms of soldering. The ring main is almost certainly functioning correctly.
However, the problem is whether I've left a serious problem for future owners of this house by
a) using electrical tape to cover the joints (answer: yes) b) degrading the insulation to the extent where it will catastrophically fail in a few years' time.
I think my only real solution is to put these joints into blank socket boxes accessible to anybody, so at least a future electrician can open them up and discover what's been done. This will look ugly (the joints are at head height), but I guess I can strategically hang some pictures over the boxes when it comes to sell the house.
Lectures are sometimes needed for those of us with more enthusiasm than experience, and your help is received with thanks.
eh? P = VI so the power from 5A is 230 * 5 = 1150W.
Rearranging the above formula gives P/V = I or 0.2 and a bit amps for
50W. I think you did V/P. B-)
After a paws for thought, just use a quick setting epoxy :-)
I think you can also get putty that takes the heat away . Stuart
Shift THELEVER to reply.
I would say there is a pretty good chance you have a decent joint - the fact the wires were twisted together first will probably ensure that (I have uncovered enough "permanent" joins made like that without solder in peoples houses in the past!
The soldering iron you used sounds like it was too small or needed a bigger bit on it. An insulation resistance check at high voltage ought to put your mind at rest however.
(personally I would have used crimps)
Elastic bands holding the pliers shut works for me.
Do NOT solder T&E.
The only soldering an electrician will do is to add bonding in a innaccessible place. This is on single-core wire, so melting of th sheath is not as much of an issue, and it will be soldering/brazin direct to a copper pipe.
Why not extend the ring properly?
If you must add a spur, you are allowed under regulations to take i from the socket.
FAILING THAT - BUY A JUNCTION BOX - IT'S WHAT THEY'RE FOR.
About £2.50 for a 30Amp box
-- state-it
As usual, take posts from diybanter with a pinch of salt.
The OP said the joint would be inaccessible - and that is NOT what junction boxes are for.
If you can't get it right, don't post.
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