Jointing mains cable with crimps

[Andy Luckman (AJL Electronics)]

In my house, the previous occupant has done all sorts of terrible things with the electrics, the shower (9.5kW) fed with 2.5mm to name just one!

The lates bodge found was behind a wall cabinet. At one time, there used to be a double mains socket, which has been removed complete with back box and replaced with a standard round junction box. The hole has been gouged out to allow it to be sunk. From this, a short spur to a new, lower position.

My requirement is to open the ring at this point and run another couple or three of sockets. I know that crimps are the way to go, but tell me this:

1) Are these crimps the same blue ones as I use for auto electrical work?

2) Should the earth be connected straight through, or connected to a replacement back box (removed during this bodge).

[Dave Plowman (News)]

If you replace the back box it then becomes 'accessible' so you could use choc blocks for the connectors and fit a blank plate as a cover. I don't think it matters that it's behind a cupboard.

I don't like those blue crimpy things. ;-)

[Alan]

No - those are for low voltage, multi-strand wire. T&E is not.

You'd need crimps designed for the wire size and current - probably the yellow coupler type ones, and a proper (ratchet) crimp tool to close them properly - not the el cheapo ones which cannot apply enough force.

Alan.

[Rob Convery]

AFAIK there is no difference in contrsuction between the blue/red and yellow bullets. The only difference is the size of them so I can't see how one would be for stranded and another solid. Definatly agree that its worth getting the proper crimpers if you are going to use them

[Dave Plowman (News)]

I can't see any difference between ones bought from Halfords or from TLC. Neither does RS etc list ones for low voltage stranded and mains solid core - and they of course would cover both events with their products.

TLC give red 1.5mm blue 2.5mm yellow 6.0mm

So for coupling 2.5mm blue is correct.

[Andy Luckman (AJL Electronics)]

I have some proper tools, all I need then is the yellow crimps, CPC? or Dave's suggestion of chocolate blocks. I am going to make it accessible ish, so I suppose that's OK.

[Alan]

I though the OP was referring to the "Scotch" or "Snap-lock" type blue connector often used in car wiring mods, like this:

[Alan]

I though the OP was referring to the "Scotch" or "Snap-lock" type blue connector often used in car wiring mods, like this:

[Dave Plowman (News)]

I'd sincerely hope not. Dreadful bodges. And they're not crimps but a crude IPC type.

[Tony Williams]

I would be cautious about crimps, unless the blurb actually said the word 'solid'.

For example, I assume that all RS crimps are for stranded wire, with the only exception being the range from Solistrand, whose blurb actually does say "designed for solid, stranded, and irregular shaped copper conductors".

The Solistrands are uninsualated crimps, of a thicker gauge copper than usual, with heavy serrations down the bore, presumably to bite into solid copper wires.

[Tim Mitchell]

In article , "Andy Luckman (AJL Electronics)" writes

I can't see what's wrong with the original round junction box set into the wall. Why is using choc block better than that?

[Dave Plowman (News)]

The 'standard' red blue and yellow pre-insulated types make no mention of this anywhere I've seen them on sale.

And I'd expect Halfords to sell them for car use - ie flex, and TLC for mains cable - ie solid in the smaller sizes. Or at least to state if they were only for use with flex.

[Andy Luckman (AJL Electronics)]

No no no. I said "auto electrics", not firestarters. :-)

[Andy Luckman (AJL Electronics)]

Because I want to open the ring at that point. There are insufficient terminals in the box.

[Chipmunk]

As has been said further down this thread, the crimps you'd need to use would be the blue 'butt splice' ones, using a decent crimp tool.

However, seeing as you're planning to use a new backbox anyway, my suggestion would be to go with choc block strip connector because it allows you more control over the connection strength.

The earth should go to the new box at at least one point.

[Dave Plowman (News)]

Yup - but I'd use a choc block for the main earth connection and just run a tail to the box terminal.

[Andy Dingley]

Crimps are relatively non-fussy about stranded vs. colid core cable. For most combinations the same crimp terminal can be used, although the ideal crimping force is slightly different.

If you're using pre-insulated crimps (ghastly things that they are) then the vagaries of trying to deliver a controlled force through a squashy plastic sleeve give rise to far more variation than solid/stranded cable.

[Dave Plowman (News)]

Yup - never use them these days on cars. I bought the proper crimping tool for Lucar connectors from Vehicle Wiring Products, so now use crimp connectors exactly the same as the makers ones.

[BigWallop]

So did I Alan. :-)

[Pete C]

electrics, the shower (9.5kW) fed with 2.5mm to name just one!

I'd consider using those on solid core to be a bodge, however they're crimped.

I'd only use ones specifically designed for solid core and crimped in the recommended way.

cheers, Pete.