Part P and first fix

[ban-all-sheds]

Junction boxes are not required on a new job. Anyone that tells you they are probably isn't very good at designing electrical installations. I genuinely can not remember the last time in installed one.

If you had a room with, say, 8 wall lights in total, what is better about having two cables running down the wall to each one, looping all around the perimeter of the room, than using a star topology from a JB?

A wiring centre for a heating system would not be installed at first fix.

The chances of you getting away with that cop-out are approximately a tad less than zero.

Whether you want to call it first-fix, or not first-fix, is entirely up to you, and entirely irrelevant, for the principle is exactly the same - something brand new being designed to go in for the first time.

How would you do that with the wiring for a CH system without a junction box?

 

[RF Lighting]

The op is at first fix stage and said they have junction boxes fitted. This tells me the wiring is wrong.

I'm not getting into semantics with you over what does or doesn't constitute a junction box.

I would loop round the lights because this is the best way to do the job.

 

[crystal ball]

Thats your opinion, nothing wrong with that method, and nothing wrong with the JB method as long as each is correctly installed

 

[ban-all-sheds]

I'm not getting into semantics with you over what does or doesn't constitute a junction box.

Because you realise you'd find it hard to argue that one of these is not a junction box:

Would you also like to argue that neither is one of these:

?

I would loop round the lights because this is the best way to do the job.

In that case it must be better than other ways.

What is better about having two cables running down the wall to each one, looping all around the perimeter of the room, than using a star topology from a JB?

OOI, have you ever encountered lights with push-in spring terminals where you can only get one conductor into each?

 

[SimonH2]

Each installation has it's own characteristics - some will suit having a JB, some won't. A "simple" installation would suit looping at switch or light, a "not simple" installation would be better with a JB than a rats nest stuffed into the back of a switch box - would you really like to see all this behind a switch

I've seen a number of switches where I would class the wiring as "unsatisfactory". In one place I looked at (but didn't buy for a variety of reasons including the wiring) there were something like EIGHT cables (mostly T&E, some 3C&E) in a 16mm deep switch box

For wall lights, I'm definitely with BAS that some lights simple do not suit looping through - the ones we have in our living room (put up by the previous owner) have very little space for the cables, and the (plastered in so no spare could be pushed back to cater for "oops" moments) cables are cut fairly short (twice the cables, twice the space needed to for spare length to be left), if we had to replace them, there's a good chance that the cables could be too short to reach the terminals of the new fittings.

PS - I'm aware of a number of issues in the JB, TBH I wasn't really that happy with it when I'd finished

 

[ban-all-sheds]

would you really like to see all this behind a switch

RF clearly would.

He would also like, in a brand new property, to install all the wiring for a CH system with no wiring centre, and any pendant lights without ceiling roses.

And to simply walk away and refuse to take a job where the customer had chosen lights with push-in terminals accommodating a single L, N & E.

 

[John D v2.0]

I've done pretty much the same as you Simon, although I used a din rail box and those rail mounted demountable wago style connectors. This brings all the wiring back to a single (hidden) point on each floor to allow for home automation in future. Use a lot more cable but all the cables come together in one place.

 

[JohnW2]

I've done pretty much the same as you Simon, although I used a din rail box and those rail mounted demountable wago style connectors. This brings all the wiring back to a single (hidden) point on each floor to allow for home automation in future. Use a lot more cable but all the cables come together in one place.

For what it's worth, I also have similar arrangements in some parts of my house.

Particularly in relation to a very simple/straightforward installation, RF is obviously right in saying that an installation usually can be wired without the use of any 'conventional' JBs (it's just plain silly to confuse the issue by lumping these together with ceiling roses and CH 'wiring centres'), and there is clearly something to be said for minimising the numbers of joints/connections (even if allegedly "MF").

However, as has been suggested, there are plenty of reasons why, in particular circumstances, it may be sensible and/or 'convenient' to use at least some JBs.

As with so many things, I think that application of common sense and judgement is what is really required.

Kind Regards, John

 

[crystal ball]

For what it's worth, I also have similar arrangements in some parts of my house.

Particularly in relation to a very simple/straightforward installation, RF is obviously right in saying that an installation usually can be wired without the use of any 'conventional' JBs (it's just plain silly to confuse the issue by lumping these together with ceiling roses and CH 'wiring centres'), and there is clearly something to be said for minimising the numbers of joints/connections (even if allegedly "MF").

However, as has been suggested, there are plenty of reasons why, in particular circumstances, it may be sensible and/or 'convenient' to use at least some JBs.

As with so many things, I think that application of common sense and judgement is what is really required.

Kind Regards, John

Hmm does the JB method have more connections than looping from switches or roses, I imagine it is a similar amount

 

[JohnW2]

Hmm does the JB method have more connections than looping from switches or roses, I imagine it is a similar amount

I think the answer of that has to be "it depends" (on lots of things). I've certainly seen installations which have involved the interconnection of multiple JBs, and that almost certainly ends up with 'more connections'.

However, as I said, I'm far from 'allergic' to JBs - witness the fact that there are countless in my installation (not the least because of all the modifications which have been undertaken over the years/decades)!

Kind Regards, John

 

[crystal ball]

I was thinking of a new build or rewire, with J701 style JBs I don't think there will be much in it

 

[JohnW2]

I was thinking of a new build or rewire, with J701 style JBs I don't think there will be much in it

You're probably right - but that is just one of the 'it depends' scenarios.

Whether there would be any real point in using J701s or suchlike rather than ceiling roses (or equivalent) is another matter. Again, I suppose that "it depends".

Kind Regards, John

 

[ban-all-sheds]

it's just plain silly to confuse the issue by lumping these together with ceiling roses and CH 'wiring centres'

It absolutely is not.

That RF puts his hands over his ears and says "la la la la can't hear you" when those are mentioned shows that he knows full well that they are types of junction boxes and that there are no fundamental reasons why they should not be used. That there is one very appropriate use of a JB, namely a CH wiring centre, immediately opens the door wide to the possibility that there are other appropriate uses of them.

and there is clearly something to be said for minimising the numbers of joints/connections (even if allegedly "MF").

Of course. I don't think anybody has spoken in favour of their gratuitous use.

However, as has been suggested, there are plenty of reasons why, in particular circumstances, it may be sensible and/or 'convenient' to use at least some JBs.

I agree. Which is why I took issue with

There shouldn’t be any junction boxes on a new installation.

Junction boxes are not required on a new job.

As with so many things, I think that application of common sense and judgement is what is really required.

Indeed. And if common sense, judgement, or other design choices make the use of JBs preferable then you use them, rather than saying that they shouldn't be and anybody who does probably isn't very good at designing electrical installations.

I have, I can promise you, had lights with push-in spring contact terminals where it is both physically impossible and contrary to the installation instructions to get more than one conductor in each, and therefore it is both physically impossible and contrary to the installation instructions to loop from one light to the next.

 

[Idrisdraig]

As much as I hate to get this thread back on track ... ie about getting the wiring tested and certified, and what I can do in terms of cladding walls, flooring etc without causing problems.

I've had a look at the building over the weekend. It's relatively small scale (something like a small stone stable block that's being converted into an art studio / garden office). A few ceiling lights. A few sockets. Nothing complicated.
The wiring is all new and looks very neat, and there are good drawings to show what has been done and what still needs to be finnished. Nothing has been connected to the CU yet.

There appear to be a couple of cable runs for mains sockets and lights in one room that can't be seen (as they run through finished stud wall), but there is nothing to suggest there are any hidden junction boxes.

There are a couple of multi-way junction boxes for lighting, mounted where they are easily accessible. They look similar to the J701s.

My sister has no budget (she'll owe me lots of beer!!!!) so if we can get away with only getting a sparky in for a day that would be great.
Obviously they'll need to connect the mains and lighting to the CU, a couple more sockets and lights to install, and test and inspect what's already been done, but if it's more than a day's work they're taking the ...
Building Control have apparently signed off the renovation and are just wating on the electrics to be finished before they're happy.

It sounds as though getting what's there already tested shouldn't be a problem. Does that make sense?

 

[Taylortwocities]

Find your electrician and ask him/her. They are the only one who can say if they'll be prepared to notify the works.