Wiring a JB like the pros

[AdamW]

I am about to install a junction box to move the location of my immersion heater (accessible, of course - in the loft.)

I was just thinking: when I install a JB I wire them in so I have the earth between the neutral and live, i.e. in the same orientation as the T&E.

Is this correct, or is there really no preference for this? A minute point, but I think too much!

In addition, I bought the JB at an electrical trade supplier near work. When I examined a 20A JB I also bought I noticed it was branded "Contactum": I remember reading someone here saying that they only supply DIY chains!

I was a little shocked at the prices too, 1.56 + VAT for a 20A 4 terminal JB. They only had them in black, which upsets the aesthetics of my whole installation now! I even asked if they had any in white, or any MK, but alas no. Think I will try out all the suppliers in my area over the coming months and see which I like best. Big orders online are great, but for small bits the delivery charge makes it pointless.

 

[securespark]

forgive lower case i am typing with baby on one knee....

color of plastic not too important in the loft, though. contactum supplies w'sale too.

i pay 79p + for bg jbs but thats for 20+ (and for 30A too, ooops sorry!)

if you only buy one and are not in trade you will pay more.

most jbs are brown. some are white but i have only seen the really cheap ones in white.....apart from mk rectangular one 1130whi

guess in your neck of the woods the cable is white - in nw we use grey.

have heard in london anyway that white is used by pros and grey by diy, but here is other way round.


guess core order is not too important, but i put earth in middle too.

 

[crystal ball]

I have noticed on most of the house doing up progs on TV they seem to use white T&E even the pros, they are probably mainly filmed in the south, I have never been offered white cable at the wholesalers, yes I am NW too. Ashley used to do white JBs round and oblong have a look at hager.co.uk

 

[plugwash]

i'd imagine while cable is slightly more expensive to make

but it looks better when clipped direct and is easier to find in dirty lofts

 

[Big_Spark]

Just to pour cold water on assumptions, the colour of the outer sheath of T&E is solely dependent on two factors..who made it, and whether the outer sheath is LSF or not.

In the stores we have both Grey and White T&E of all sizes..all the cable is made by Pirelli, Crompton or BICC.

When we order it, we ask for normal PVC to be grey and any LSF we order to be white..makes it easier in the stores!!

 

[AdamW]

is easier to find in dirty lofts

This is the main reason I would have preferred white ones. Although all the cabling is white so I just have to look for the shadow in the middle

That is pretty interesting about the grey/white pro/diy thing. All the sheds I have ever been to only stock it in white, those sheds being in Hertfordshire, Surrey (within the M25) and London. However I doubt my flat was a DIY job, it certainly hasn't been rewired and the whole thing is in white.

It might be a good idea if they made it so you could only buy one or the other unless you could produce a Part P ( ) card. Then when someone goes to buy a place the surveyor can instantly say "yes, this has been DIYd, I request you have an inspection", or "all pro work, have an inspection anyway". Do the same with pipe, and bricks, and carpets

 

[AdamW]

Oh, and the 20A 4 terminal JBs I have bought in the past are 65p each (at TLC) and they feel pretty sturdy... MLA brand I think.

Is Contactum really a bad make? JBs feel averagely sturdy to me, perhaps the lids could be a bit less plasticky but aesthetics aren't important really in a loft.

 

[ban-all-sheds]

guess core order is not too important, but i put earth in middle too.

And doing that also make it easier if you don't want to actually cut the cores of the cable you're joining into (apart from the earth, where you have no choice if you want to sleeve it)

 

[plugwash]

custting the earth and not the others actually works very well

because the earth tends to take the shortest patch through the box

 

[securespark]

All the sheds I've seen in NW have grey, but in 80's (now I think) all sheds had white. Confused? You will be.

 

[dingbat]

All the sheds I've seen in NW have grey, but in 80's (now I think) all sheds had white. Confused? You will be.

And of course there is a new distinction as, at the time of writing, the sheds round our way still stock only red and black cable, whereas the wholesalers are selling harmonised colours. How long before DIY-ers get to know about the colour changes, I wonder, and will B & Q put both on the shelves at the same time?

 

[plugwash]

i don't think the color change will cause big danger to diyers as they are already used to flex in the new colors

 

[dingbat]

i don't think the color change will cause big danger to diyers as they are already used to flex in the new colors

Yeah, true. Except now I'll just get five calls a week from people who have connected 'all three browns together and all three blues together' and blown their lighting fuse.

 

[ban-all-sheds]

How long, I wonder, before the first post here from someone saying "I bought a new light to fit and when I took the old one down I found 2 black wires 2 red wires 1 blue wire and one brown wire. I tried joining the reds together and the blacks together, and connecting the light to the brown and the blue, but now half the lights in my house don't work and when I turn on the switch the fuse blows"

?

Perhaps we should run a sweepstaket to predict the date, say to the nearest month...

 

[dingbat]

It's bad enough looking at the live black, grey and three browns in the two-ways I've just put in... especially as one of the browns is a slightly lighter colour! (One of the cores of the twin brown switch cable is quite definitely a few shades paler... which is nice.) The brown sleeving is gopping though!