Confused

[Pete999]

I'm going to ask what might sound dumb coming from someone of my age and experience, I don't do much now and have done very little in the way of domestic installations, having spent much of my time on commercial or industrial work, thats not to say I don't know how to install domestic electrical installations. The confusion lies with junction boxes under the floors of houses during a rewire, many moons ago on a social housing project we wired everything lighting wise, back to a central point on the first floor, and connecting the lighting points and switches in a large junction box, likewise if we needed to add a 13a socket we would sometime break into the RFC with a 30a JB fitted to a noggin under the floor. My question is, is this still allowed? I mean fitting a JB under the flooring and forming a trap, where possible in the floor boards.

 

[davesparks]

It's got nothing to do with knowledge it's about making things simple neat and quick

An RB4 is simple quick and neat. And you don't have to buy a different one for different numbers of switches and lights.

I can't imagine a prewired JB being very neat really. I would imagine you'd end up with cables entering from all directions.

 

[Richard3009]

cables from all directions, well with a central hub surely that's the general idea

 

[davesparks]

No, that would be awful.

You have all cables approach an RB4 from one direction. In a loft the would often all be clipped along a binder or on top of the collars around the edges.

The RB4 gets mounted on a piece of wood with a good 8 inch space for the cables to be clipped up to it and written on. With a little bit of thinking and a logical working order you can get each switch cable next to each light cable without any cables crosding over.

 

[Richard3009]

how the hell does a cable approach from a certain direction, give me a cable and I will make it arrive at any angle you wish at a JB

 

[davesparks]

I don't doubt that you will have cables approaching from any and all angles.

I however will work with neat and tidy straight lines and right angles so far as is possible.

 

[Engineer54]

Anyone using Sureway prewired JB's for complete house wires?

Sounds a bit like the old central point ''Octopus'' wiring system of the 70's.... Didn't really catch on, and many got ripped out, not that many years after they were installed. Weren't too readily adaptable for additions etc, and often ended up with needing additional JB's to get over the central Octopus systems restrictions, which basically nullified any perceived or otherwise advantages of the system...

 

[Engineer54]

How do you wire your lighting circuits then? Upstairs is always an RB4 in the loft when I wire a house.

Why would you introduce a JB into the installation on a rewire or new build?? I can't see the point of that at all, surely point to point wiring is the name of the game!!

 

[Sparkie30]

How do you wire your lighting circuits then? Upstairs is always an RB4 in the loft when I wire a house.

really ? Feed in the switch then switch to light, neutrals in the wago. Easy to second fix, easy to trace, no brown sleeving needed. Simples

 

[GMES]

JB's on a rewire or new build. That's as rough as a badgers...

Next thing you know they will be allowing Limitation's on the Installation Cert's. The world is going Mad.

 

[Engineer54]

really ? Feed in the switch then switch to light, neutrals in the wago. Easy to second fix, easy to trace, no brown sleeving needed. Simples

In T&E, that's the very LAST way i'd ever wire a house!! Switch looping can lead to backboxes being well an truly packed, and for no good reason either!!

Also opens the door to allow DIY'ers to easily get up to all sorts of unmentionables on a lighting circuit!!!

 

[imago]

There seems to be a growing desire to have a 'one size fits all' approach to methods in recent years. Maybe Part 'P' is to blame? Maybe it's lack of wider experience of other methods? I'm not sure what the cause is, but it's not a good thing IMHO.

I use whatever method is best suited to the installation at the time. For example, I've just done a rewire of what was a completely gutted three bed stone built terraced house. There are three rooms that have downlights, kitchen, bathroom, and living room. They are wired in a variation on the spider, in this case three legs supplying two D/Ls each, which means three junction boxes. The JBs are 100mm adaptables containing Wago connectors. Each one is accessible (above the CU for the kitchen, in the soild stack boxing for the bathroom, and under the stairs for the living room). All the cables are labelled going into the boxes.

The reason for doing it this way on this job is that the 140 year old floor joists don't need to be drilled. Doing so would weaken them to an unacceptable level, so on this job using junction boxes was the best solution to overcome something which has nothing to do with the electrical installation directly.

The same work in a different house and there may no be a single JB, and the DLs would be daisy chained.

Horses for courses, and the reason that a signature is required for 'design'. Although that does assume that someone gives some thought to it and actually does do a design rather than just nailing up a collection of cables!

 

[Engineer54]

I don't think anyone experienced, is daft enough to think there is a ''One Size Fit's All'' method, ....as you say, the design and installation method should suit the installation....

I have a cousin that owns a 160 odd year house, and his joists would put any modern day house joists to shame, most being 3 to 4'' wide and as hard as steel. A good few years ago, i literary blunted a good flat wood bit, drilling a hole in just 3 of them, the last i had to finish off with an auger drill and it didn't do that drill much good either.... No way a 20mm hole was going to weaken those joists, wherever the hole(s) were drilled along it's length.... lol!!

 

[richy3333]

How do you wire your lighting circuits then? Upstairs is always an RB4 in the loft when I wire a house.

Eh? Like 99% on here - loop in and out at switch or light point. Preference for light point for a number of reasons

 

[imago]

I don't think anyone experienced, is daft enough to think there is a ''One Size Fit's All'' method, ....as you say, the design and installation method should suit the installation....

I have a cousin that owns a 160 odd year house, and his joists would put any modern day house joists to shame, most being 3 to 4'' wide and as hard as steel. A good few years ago, i literary blunted a good flat wood bit, drilling a hole in just 3 of them, the last i had to finish off with an auger drill and it didn't do that drill much good either.... No way a 20mm hole was going to weaken those joists, wherever the hole(s) were drilled along it's length.... lol!!

True, but there seems to be a lot of things that are described as "you must" "you can't" or "the way it should be done is". Junction boxes being the current topic, people are saying that they shouldn't be used when as you've said the installation method should suit the installation.

A good case in point are the joists, which are 6" by 3" as you describe. Unfortunately these have been subject to quite a bit of less than sympathetic DIY and 'work' over that 140 years. Channels cut on the undersides, holes drilled for cables in the '70s, additions made and channels cut into the top faces etc. 140 years allows for several generations of cowboys and idiots to do their thing!

 

[Engineer54]

True, but there seems to be a lot of things that are described as "you must" "you can't" or "the way it should be done is". Junction boxes being the current topic, people are saying that they shouldn't be used when as you've said the installation method should suit the installation.

A good case in point are the joists, which are 6" by 3" as you describe. Unfortunately these have been subject to quite a bit of less than sympathetic DIY and 'work' over that 140 years. Channels cut on the undersides, holes drilled for cables in the '70s, additions made and channels cut into the top faces etc. 140 years allows for several generations of cowboys and idiots to do their thing!

If we are talking about a ''typical'' installation in the general sense of the word, there would be no need for any JB's whatsoever. It's only when we get outside of the typical and into specifics that JB's can or will become viable!!

You'll be surprised just how much punishment a 6'' X 3'' joist can take. And if there are that many existing unused holes and slots in these joists why cant you use them for your cables to pass through??

Weren't many cowboys about for the vast majority of those 140 years, it's only relatively recently the cowboy has evolved...lol!!