Domestic Lighting Circuit Methods In New Builds

[Les Macaulay]

To my knowledge, there are 3 methods of splitting the line conductor in each lighting circuit:

Joint box below floor, or above ceiling
Three terminal ceiling rose/batten lampholder
Joint in switch box (neutral)

I am wondering which method is most commonly used in new houses.

I have been in this house for nearly forty years and after upgrading the central heating from warm air to combi-boiler, the Scottish Gas Company's installers connected three smoke detectors to an octopus joint box.
After several years the downstairs lighting occasionally fails. After a time these lights begin to work again.

Being a retired spark, I checked all connections in the CU and they were all secure.

Not knowing where the octopus joint box for the entire four apartment house was located I lifted the fitted carpet upstairs landing and found it.

The line connection had approximately six conductors below a brass plate, but the added line conductor had caused the plate to ride on the additional conductor which was at an angle across the other six. Since the brass connection plate (about one inch long and secured at its centre by a single 2BA or 4mm brass screw had failed to put equal pressure on all conductors, time had caused it to develop an intermittent o/c of the line conductor feeding all downstairs lighting.

Summing up don't you think ALL future new builds should not use the octopus joint box system especially where it is sited below wooden floors with no removable hatch left for access nor even an indication of the position of same.

 

[Octopus]

You don't need any joints especially on new builds.

I did say that..

 

[westward10]

I could understand it on the old two plate system years ago where circular junction boxes made the loop in/out/switching point but not in this day and age. As Murdoch says, poor design.

 

[7029 dave]

I did say that..

I KNOW , just backing up what you said.

 

[Hardwired]

Don't thing i've saw anyone install anything other than loop in at switch in the past ten years or so. Anything else is just a pain in the hoop.

 

[Les Macaulay]

I KNOW , just backing up what you said.

Thanks, guys, for all your replies.
Not one of you has said anything that I don't agree with. We often do things without thinking why. I try to think of myself or A.N.Other, coming back to the installation for maintenance, or replacement.

 

[Ian1981]

You need joint boxes when lights have been wired with the mains in out to the rose which can be standard in a new build when the house is not sold and it's basic spec.
Nothing wrong with this but say you then wanted to install downlights then joint boxes will be necessary.

 

[Les Macaulay]

You need joint boxes when lights have been wired with the mains in out to the rose which can be standard in a new build when the house is not sold and it's basic spec.
Nothing wrong with this but say you then wanted to install downlights then joint boxes will be necessary.

Alternatively if we all in future use the switch boxes as the joint box, then no joint boxes are necessary, even with down-lighters. The point is, joint boxes, if unable to be left easily accessible, then don't use them at all. The switch box method also makes inspection and testing easier and much quicker without going below floors or into attic spaces.

 

[Ian1981]

Alternatively if we all in future use the switch boxes as the joint box, then no joint boxes are necessary, even with down-lighters. The point is, joint boxes, if unable to be left easily accessible, then don't use them at all. The switch box method also makes inspection and testing easier and much quicker without going below floors or into attic spaces.

Can make things difficult to tap off a supply for another lighting point such as adding a light in a loft.
A harder task when all mains are located in the switch.
You maybe able to fish a cable down the wall depends really.

As said already if designing for downlights mains to the switch, if not there's no reason why you can't loop in out at the light.
No wrong way really.
Also one of our apprentices said the preferred way teaching at College is mains in out at the switch as it eliminates time spent 2nd fixing a light on steps which anything working off the ground is considered working at a height, eliminating accidents.

 

[Octopus]

You need joint boxes when lights have been wired with the mains in out to the rose which can be standard in a new build when the house is not sold and it's basic spec.
Nothing wrong with this but say you then wanted to install downlights then joint boxes will be necessary.

I disagree. Why do you need joint boxes, especially hidden ones the op is going on about.

Neural at switch is the way I normally go these days.....

 

[Les Macaulay]

Can make things difficult to tap off a supply for another lighting point such as adding a light in a loft.
A harder task when all mains are located in the switch.
You maybe able to fish a cable down the wall depends really.

As said already if designing for downlights mains to the switch, if not there's no reason why you can't loop in out at the light.
No wrong way really.
Also one of our apprentices said the preferred way teaching at College is mains in out at the switch as it eliminates time spent 2nd fixing a light on steps which anything working off the ground is considered working at a height, eliminating accidents.

 

[Les Macaulay]

You are right, Ian.
Was thinking of the type of terrace house where the octopus system has been used with the large joing box below the upstairs floor and client has composite flooring fitted. This would be a nighmare to gain access to the joint box. As you say, there is no right way.

 

[davesparks]

^^ if you are doing a new lighting circuit, why do you need ANY form of JB?

Edit: Poor design and install IMHO

I guess I'm guilty of poor design and install then!
When it's possible to locate it sensibly I always use a central RB4 type joint box for a lighting circuit.

 

[Octopus]

When it's possible to locate it sensibly I always use a central RB4 type joint box for a lighting circuit.

Best you define "sensibly" as I can't find that in the BYB!

 

[davesparks]

Best you define "sensibly" as I can't find that in the BYB!

Indeed, it's based entirely on my own opinion, and where I would be inclined to look for it.

So if in a loft I would mount it above insulation level, on a purlin or a board screwed to the uprights of trusses.
In a chalet bungalow it would be just inside the access into the eaves, again mounted above insulation level.
And if possible I will have a light fitting near it which is fed via a different circuit.

 

[Sollyg]

Hi please can somebody help answer my question
I got a total of 50 spot lights in a house i am goin to install. I am goin to use wagos
Do I HAVE to put every light wagos connectors in an enclosure if so why?
Some body said just put insulation tape on them
All this is happening in terraced house with no insulation in ceiling and the lights are double insulated , all gonna b with led 4 watt bulb
Thank u