Junction box problems HELP!

[andemz]

I have today purchased a couple of junction boxes to practice wiring into.

I wired in 4 wires. Supply, Switch, Wire to light and supply to next junction box. I only used 2 foot lengths of wire to just get use to stripping wire etc.

I have a farily big junction box 20amp 2.5mm. With 4 brass coloured terminals in a straight line. I used 1.5mm cable and did a neat job.

To you sparks and avid diyers.. Do you have the same problem of struggling to get the wires into the terminals as i found this to be a painstaking long task?

Please advise on any methods that will ease my working.

 

[Lectrician]

A decent J box from a wholesaler.

Use 1mm cable for small (99% of domestic) lighting circuits, 1.5 is mainly used for larger houses or if spec be someone.

 

[andemz]

I guess you just have to work at getting those wires in then.

I do live in quite a large house and all of my wiring is in 1.5mm. I took a look in the loft at the 3 core and E wire 1.5mm used for 2 way switching etc that looks really thick. I wouldn't like to mix 1mm cable up with 1.5mm cable if i was going to do something in the future i guess it would be better to stick with the 1.5mm cable.

Given that it is 1.5m is it a matter of hard work and persistence?

 

[AdamW]

I have used 1.5mm for all the lighting in my flat, but that is because the existing lighting circuit was all in 1.5mm. I have seen wiring where the loop through is in 1.5mm, but the switching cable is in 1.0mm. Seems bad practice to me (no fusing down before changing cable size), but I believe it is quite normal.

The way I use to wire JBs is:

1) Strip off the outer insulation of the T&E, so that it runs into the JB but not all the way to the terminals.
2) Decide what terminal is going to be for what.
3) Using side cutters snip each wire to a length suitable for its terminal.
4) Use a wire stripping tool (no knives, or burning it off) to strip back just enough that it is 1-2 mm from the terminal.
5) When all cables have been done, work one terminal at a time, rather than put all wires in and then tighten all the screws afterwards.

Stripping the outer insulation from T&E is a bit different to the inner insulation. After some research I found most references were suggesting to slit down the length to be stripped, along the centre (so no damage to inner insulation). Then pull it back and cut it off. If you try to run a knife around the T&E you are likely to damage inner insulation.

Is there a special tool sparks use to strip outer insulation?

 

[AdamW]

Oh, and even with fatter cables it isn't any harder to wire JBs. With the 20 and 30A JBs I have found they usually have big slug screws that clamp the wires down rather than small mains-plug type screw terminals.

In fact, the easiest JB I ever wired was a 30A, used to connect two lengths of 4.0mm. Because the cable is stranded, I found it easy to slightly spread the strands and they held it in place until I had both cables in.

 

[breezer]

use of 1mm for a switch cable is also done to make identifying said cable easier

 

[AdamW]

True, it does indeed. Avoids the need to open up JBs or roses to see which cable has the two reds (or should that be two browns now?) so you can trace cables in lofts without too much effort.

 

[dingbat]

I always remove all the screw from the JB terminals I intend to use (don't lose the screws!). Then I trim and strip each conductor to exactly the size I want, working on one length of multicored cable at a time and taking into account which box entry point I want to use. Then it's a simple matter of wiring up each terminal in turn, holding the cores down with a small screwdriver while popping the screw back in. It's easier than it sounds, but it does take a bit of practice to get right. (Have an identical JB handy for spare screws because you will lose one sooner or later.
(Oh, by the way, your JB's must be accessible for future maintenance and should be screwed down - this is best done before you start working, if you can)

 

[benjiman]

Stripping the outer insulation from T&E is a bit different to the inner insulation. After some research I found most references were suggesting to slit down the length to be stripped, along the centre (so no damage to inner insulation). Then pull it back and cut it off. If you try to run a knife around the T&E you are likely to damage inner insulation.

Is there a special tool sparks use to strip outer insulation?

The way I saw a sparky do it was he cut a little of the cable to just get at the earth with a plier. Then he used the plier to grab hold of the earth wire and then pulled it down. This automatically stipped the cable to the lenght you require. The more you pull it the more outer insulation comes of. Then just cut it back.

 

[Lectrician]

Many sparks do it that way, but it can stretch the earth (says the college to my apprentices )

 

[fubar]

Many sparks do it that way, but it can stretch the earth (says the college to my apprentices )

Well, they are bending the cpc beyond the minimum radius of bend, aren't they

--
Michael

[edited tense]

 

[spence_spark]

if you are going to be doing a good few invest in a pair of automatic wire strippers approx £10 - £20 mine are absolutely invaluable, place cable in the jaws pull handles together and bingo 1 perfectly stripped T+E or whatever then repeat process for the inner cores

 

[ban-all-sheds]

Many sparks do it that way, but it can stretch the earth (says the college to my apprentices )

Well, they are bending the cpc beyond the minimum radius of bend, aren't they

--
Michael

[edited tense]

Yes they are - don't do it that way.

if you are going to be doing a good few invest in a pair of automatic wire strippers approx £10 - £20 mine are absolutely invaluable, place cable in the jaws pull handles together and bingo 1 perfectly stripped T+E or whatever then repeat process for the inner cores

What make are they? I've tried some of those and not found them to work very well.....


andemz - a couple of these can be handy for holding cables in place:

 

[spence_spark]

I have to admit I bought them from halfords £11-99 not sure if own make or not. However i'd fully recommend them for what its worth
be aware though only upto T+E 6mm2 will fit in jaws,anything bigger requires a differing method. hope this helps!

 

[ban-all-sheds]

Well - most of the time it's 2.5mm² or less.

Wish I could remember where I saw (it was some years ago), a fantabulous tool - you pushed the end of T/E (I think it only went up to 4mm) into an aperture, and with one squeeze of the handle it:

Removed the sheath
Stripped the ends of the conductors
Splayed the 3 conductors apart

wasn't cheap though...