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]

Considering the pendant flex is not part of the installation wiring I don't see your point?

 

[specs]

Considering the pendant flex is not part of the installation wiring I don't see your point?

I knew you wouldnt

 

[davesparks]

Excuse me? I just don't see what you are getting at, considerations for a pendant flex are completely different to installation wiring.

 

[Meggerman]

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!!!

Have you been on a new build site in the last 10 years?? They are all wired like this with fed switches. We don't install 16mm boxes anymore!! Makes 2nd fixing light fittings much quicker and all terminations still accessible.

 

[shanky887614]

Have you been on a new build site in the last 10 years?? They are all wired like this with fed switches. We don't install 16mm boxes anymore!! Makes 2nd fixing light fittings much quicker and all terminations still accessible.

ive been on about 3 self new builds and each one was done different.

loop in and out on two of them in twin and the other had single+cpc cable

 

[Engineer54]

Have you been on a new build site in the last 10 years?? They are all wired like this with fed switches. We don't install 16mm boxes anymore!! Makes 2nd fixing light fittings much quicker and all terminations still accessible.

I've worked on nothing else but large so-called blue chip projects, and i can assure you, none that i've worked on loop feed neutrals through switches. Oh and i've never seen 16mm switch back boxes on any project. But then you are probably talking about the likes of throw em up quick new house builds, where anything goes, if it save a few pennies. Nothing against a neutral being at a switch point, ''IF'' it is required to be there. other than that, it's just filling up space in any back box!! Who the hell wants to chop in 35mm back boxes on a domestic installation anyway and then have 3 T&E's to each light switch to supply in many cases a single light point. It's about as daft as pulling in a separate CPC in metal conduit!!

 

[Hawkmoon]

Excuse me? I just don't see what you are getting at, considerations for a pendant flex are completely different to installation wiring.

Yeah, pendant flex not subject to overload - fixed wiring is.

If you are going to mix cables in a circuit then protection should be applied to the smallest cable unless you can demonstrate overload protection elsewhere (eg RFC spur)

 

[Meggerman]

I've worked on nothing else but large so-called blue chip projects, and i can assure you, none that i've worked on loop feed neutrals through switches. Oh and i've never seen 16mm switch back boxes on any project. But then you are probably talking about the likes of throw em up quick new house builds, where anything goes, if it save a few pennies. Nothing against a neutral being at a switch point, ''IF'' it is required to be there. other than that, it's just filling up space in any back box!! Who the hell wants to chop in 35mm back boxes on a domestic installation anyway and then have 3 T&E's to each light switch to supply in many cases a single light point. It's about as daft as pulling in a separate CPC in metal conduit!!

Fair enough, you do large commercial projects and not houses. 25mm box is perfectly adequate, nearly all are dry lined (around here anyway), 12.5mm Plasterboard, Around a 10mm Dab, Around 2-3mm skim = no chasing required

 

[Hawkmoon]

I personally don't feed (L+N) switches without reason -

Looping in/out light fittings uses less cable (normally) and has the added bonus of making it more difficult for Mr DIY to change his own light fittings.

 

[Meggerman]

I personally don't feed (L+N) switches without reason -

Looping in/out light fittings uses less cable (normally) and has the added bonus of making it more difficult for Mr DIY to change his own light fittings.

Well when I do a quick job on way home to change a couple of pendants for fancy light fittings with no room inside, I know what I am hoping to see

 

[Engineer54]

nearly all are dry lined (around here anyway), 12.5mm Plasterboard, Around a 10mm Dab, Around 2-3mm skim = no chasing required

25mm box is perfectly adequate,

As i said ''throw em up quick'' crap seems to be the norm now. How long these cheap wood framed houses are going to last though, is another question altogether!! lol!! Once the vapour lock has been penetrated in several places, not very long i warrant!!

Not when you have 2 X 2 way switches and/or any intermediate switching, that will fill up a 25mm back box quicker than you can say, Jack Robinson!! lol!!

 

[Hawkmoon]

Well when I do a quick job on way home to change a couple of pendants for fancy light fittings with no room inside, I know what I am hoping to see

Yes but you have more chance of acquiring that job in the first place if the wiring looks 'awkward' to the householder - with 2 cores + earth it's just too easy for them to fit the lights themselves.

Lost count of the number of calls I've had over the years saying 'I put up new light in Lounge, reds together, blacks together, now it goes bang! lol


Translation: reds/blacks means browns/blues for those of you who have just started shaving

 

[wozz]

If rather be dealing with the permanent lives at a switch rather than dealing with at the fitting.

 

[Octopus]

I'd rather fit 35mm back boxes!

 

[Engineer54]

I rather see switch looping kicked into touch, where it belongs!! lol!!

 

[GLENNSPARK]

I rather see switch looping kicked into touch, where it belongs!! lol!!

i use both methods.

like this job i`m on with at the mo...

rented and there isn`t enough money in it to start 3 platin stuff all over the place.....

so they are jointed at the switch....

but on another job i may go for 3 plate

(in fact you couldn`t easily 3 plate the top floor lights anyway on this one)...

3 plate is more cable..so = more money...and i aint losin cash for no-one..

both methods are perfectly compliant..

 

[Engineer54]

i use both methods.

like this job i`m on with at the mo...

rented and there isn`t enough money in it to start 3 platin stuff all over the place.....

so they are jointed at the switch....

but on another job i may go for 3 plate

(in fact you couldn`t easily 3 plate the top floor lights anyway on this one)...

3 plate is more cable..so = more money...and i aint losin cash for no-one..

both methods are perfectly compliant..

If your wiring from above, i'd say it was the opposite, 3 plate would be far more economical on cable. Plus you need 3 cables dropping down to every switch (except the last) involving deeper wall chases to boot!!...

 

[Meggerman]

As i said ''throw em up quick'' crap seems to be the norm now. How long these cheap wood framed houses are going to last though, is another question altogether!! lol!! Once the vapour lock has been penetrated in several places, not very long i warrant!!

Not when you have 2 X 2 way switches and/or any intermediate switching, that will fill up a 25mm back box quicker than you can say, Jack Robinson!! lol!!

lol, you are so out of touch.... who mentioned timber framed?? This is standard block construction with dry lining and anyone half decent can get all the cables in and made off. lol!!

 

[Meggerman]

I'd rather fit 35mm back boxes!

Would you really? You'd want to chase out 10mm when you had a nice flat surface to fix to before and if 1200mm from finished floor ended up across mortar join and you risk poor seating for your box? If you did new houses on price you would rethink that.

 

[Octopus]

Would you really? You'd want to chase out 10mm when you had a nice flat surface to fix to before and if 1200mm from finished floor ended up across mortar join and you risk poor seating for your box? If you did new houses on price you would rethink that.

I don't do new houses!

 

[Meggerman]

I don't do new houses!

Ok, but that is what we are discussing here, (or what the thread has drifted on to )

 

[Engineer54]

lol, you are so out of touch.... who mentioned timber framed?? This is standard block construction with dry lining and anyone half decent can get all the cables in and made off. lol!!

I mentioned timber framed houses, ....because that's what was being constructed on the housing estates i've seen on the many visits home. None of the privately built estates i've seen in the last 20 odd years have been conventional brick and block construction....

Heard it all before i'm afraid, and i've seen too many resulting squashed up messes in those 25mm switch boxes as well, for anyone to convince otherwise... As i say if a neutral is required at a switch position for say, some sort of electronic device, ...to supply an external lighting point, ...or to supply high antrim light, etc, ...Fine. But switch looping for no particular reason apart from ''I fink it's eazier'' don't cut it with me. If that's being out of touch, that's even more fine with me, i'm more than happy with that!! lol!!

 

[Octopus]

Ok, but that is what we are discussing here, (or what the thread has drifted on to )

Maybe. So on a refurb I would use 35mm boxes, neutrals to switches downstairs and probably loop at lights upstairs!

 

[shanky887614]

I mentioned timber framed houses, ....because that's what was being constructed on the housing estates i've seen on the many visits home. None of the privately built estates i've seen in the last 20 odd years have been conventional brick and block construction....

Heard it all before i'm afraid, and i've seen too many resulting squashed up messes in those 25mm switch boxes as well, for anyone to convince otherwise... As i say if a neutral is required at a switch position for say, some sort of electronic device, ...to supply an external lighting point, ...or to supply high antrim light, etc, ...Fine. But switch looping for no particular reason apart from ''I fink it's eazier'' don't cut it with me. If that's being out of touch, that's even more fine with me, i'm more than happy with that!! lol!!

usually its breeze block inside, if its being pebble dashed them concrete/ heavy breeze block's on outside.


the breeze block's inside are that sort usually a wood chisel is all you need.

 

[specs]

Yeah, pendant flex not subject to overload - fixed wiring is.

If you are going to mix cables in a circuit then protection should be applied to the smallest cable unless you can demonstrate overload protection elsewhere (eg RFC spur)

and on a lighting circuit what is the norm, , 6amp I believe, which well and truly covers my smallest cable ie 1.0mm

 

[davesparks]

So why use 1.5 at all then?

 

[specs]

Excuse me? I just don't see what you are getting at, considerations for a pendant flex are completely different to installation wiring.

what would you suggest as a fuse size for 1.0mm. I have already said it is a lighting circuit 1.5 down to 1.0. as far as I am concerned a 6amp breaker ( which is the norm for lighting in a domestic situation ) is enough protection for the 1.0mm t&e being used for the run from the switch. I am also well aware that pendant flex comes under a different consideration. The ' why' baffles me sometimes when I see what is connected to them or how they are used.

 

[davesparks]

The pendant flex has a single lamp holder on the end of it with a maximum of 100W lamp in it.

 

[specs]

So why use 1.5 at all then?

Because I consider it good practice and easily identifiable in the sw box.

 

[davesparks]

Good practice to waste good copper?
Especially in these times of copper shortages and a general love of not wasting things in teh interests of saving the planet.