Extending Wires

On Sun, 19 Dec 2004 12:43:37 -0000, "Bert Coules" strung together this:

I've done this before as it saves breaking the cable in more than one place, and as we know connections = resistance = bad. You're not actually meant to, so don't listen to me and do it to the regs, which means more joints, more resistance and more junction boxes.

Lurch,

I wouldn't dream of doing anything else. Many thanks.

Bert

If you're extending a 30A ring then the terminals only need to be rated at 20A each (just as would be the case if you could fit all the conductors in for your two spurs) and you can get six of them in one box, e.g. .

Hard to justify quite such a penny-pinching way of going about things! It's not hard to come up with reasonable scenarios in which the terminals are called on to pass over 20A - e.g. the spur drawing 15A and other sockets on the ring drawing 15A at such positions as to cause, say, 2/3 of that load to flow through the JB we're talking of. While it's imaginable to use 20A terminals safely, and quite possible to louse up the use of 30A terminals by having too little effective contact area for the conductors, I'd consider it irresponsible to use anything lower rated than 30A. In any case the OP (like the half-orphaned growing lad in the furniture-out-of-the-window "if they're anything kangaroos" joke) needs all the room he can get, whereas the JB you point to as well as having only 20A-rated terms has 6 of them taking up the precious room. And what did you want him to do with the other 3? He only needs E L & N. Running short strappers to get two of the 6 terms for each of the 3 ways only reduces the number of cores in each terminal by 1 - you'll still have two "real" cores and the strapper - and introduces more connections. Bodgesville magna.

Stefek

On Sun, 19 Dec 2004 20:03:10 GMT, Mark Williams strung together this:

Er, no.

Sorry, this bit is wrong. It's a good thing they probably wouldn't all fit, isn't it :-)!

How so?

The 6-way 20A junction box which I referred to is listed at more than twice the price of a 3-way 30A junction box from the same range.

I was talking about the insertion of a new section into the ring which you suggested in and Bert's comment about that requiring two junction boxes. There would be no spurs involved (at the junction box(es), anyway) and no terminal would be called on to pass over 20A (unless installed very close to the consumer unit).

That is your prerogative, of course. Perhaps you could make a fortune by manufacturing 6-way 30A junction boxes and selling them to responsible people?

I wasn't responding to the OP, I was responding to the sub-thread following Bert's `interruption' about his two sets of double sockets in .

I think we're talking at cross purposes. I was suggesting that a new section can be inserted into the ring (both `sides' using 3 terminals each) with a single junction box.

I don't understand what you mean by `strapper'.

I wasn't objecting to the expense! My point - as I thought was clear - was that I'd always been led to believe that there should be as few breaks in the ring circuit as possible, and so one was better than two.

Bert

Why so? If the cable only needs to be rated at 20A, why should the junction boxes have to be rated higher? Not that I would use them myself, though. 30A makes more sense, but I don't see why 20A would not be permitted.

Christian.

In message pcUwd.252$ snipped-for-privacy@newsfe3-win.ntli.net From: Scott ( snipped-for-privacy@thanks.com) Subject: Re: Extending Wires

Its not a problem if theyre done properly, only if the joint's a burnt dry mess is it going to be unsafe. I would think crimps would be much quicker and easier, but if you want to slobber:

Ensure youve got lots of wire to wire contact area, and also physical rigidity before soldering. This is easiest achieved in minimum space by twisting the 2 coppers together, but like this:

===========------ ------==========

where =: insulation and -: bare copper

Twist them until the whole thing's rigid. Note you need a decent length for it all to lock up securely. Now as long as the solder is done cleanly and all over, and the thing is insulated ok, the joint current rating will be far above that of the rest of the cable.

Note that physical rigidity before soldering is important, otherwise the usual moving of the cable during install will trash the joint, solder is weak.

NT

On Mon, 20 Dec 2004 11:19:46 -0000, "Christian McArdle" strung together this:

Now I've actually thought about it, I meant to say what you said Christian! The ''er, no'' bit was personal preference.