2.5mm² for a lighting circuit? (And why not in a ring??)

[mdbalson]

As the others have said wire the circuit in the same size cable for the whole circuit


You could loop in at the switch instead of the light, if you wanted to make it easier to put in downlights.

The cables in the loft should not look untidy, if done proparaly.

 

[edenbridge]

Good morning everybody...

...and apologies to those who I've offended with my ignorance on this matter.

It's just that the your [correct] "use the same thickness everywhere" method was at odds with [incorrect] face-to-face advice I'd received for "1.5mm loops down the trunk, and 1.0mm branches off that" which made sense to me at the time. So again, sorry if I laboured on the point too long.

Thanks to 333rocky333 for having the patience to explain the importance for calculating/testing voltage drop, and that:

...providing the total length of cable is within the maximum volt drop I can not see a problem.

I think you all know what my next question is going to be!

I've found plenty of other threads about voltage drop calculations, but it's too early in the day for that.

In the meantime, here's a picture of my proposed layout:

And again, I really do appreciate everyone's advice.

Regards
The Edenbridge Brick Wall[/quote]

 

[RF Lighting]

On a new installation, you should be aiming to use a maximum of no juction boxes at all.

I know you don't think so, but you really are out of your depth with this project. You have no idea about good circuit design, and seem hell bent on making everything much more complicated than it needs to be.

Sorry to sound harsh, but I beginning to think this is the only way to get through to you.

 

[Lectrician]

A new installation should have no joint boxes.

You should take all your cables to either the switches or pendents, this way, fault finding is so much easier.

you are going to need to run a cable to either the switch or the pendent anyway, so what harm is another one or two? If you install them neatly and correctly, 3 cables is no different to a single one.

I really do not like your 1960's approach of joint boxes in the loft. It is old and messy.

It is NOT a loop in / loop out method at all, stop calling it that! You are proposing the old school and out dated JOINT BOX method.

Loop in and out the switch or the pendent.

 

[festa]

The over current protection device in any circuit should be rated in conjunction with the lowest rated conductor in the circuit.
Ceiling rose drops wont be subject to an overload.
Ive come across lighting circuit`s wired in 1.5mm with 1mm switch drops ( twin brown) and as long as the OPD is sufficient for this lower rated conductor then their really isn't a problem.
If an electrician is to uprate an MCB from 6amp to 16amp then investigation work should ALWAYS be carried out and only uprated IF the circuit conductors and installation method allow.

 

[oharaf]

Do you ever get the feeling no matter how much advice you give to someone it still passes in one ear and out the other

Edenbridge, go back and READ ALL the advice the lads have given YOU.

Then you have several choices

1) Follow it, and probably FIU anyway

2) Follow it, balls it and call out a sparky to correct it

3) Ignore it, carryon with your 'I'll ask but I still know best' attitude and we will read about your demise in the papers in a few months.


Sorry, sometimes it just needs to be said

 

[holmslaw]

...

 

[oharaf]

Thanks Holmshaw, I think???

What does that abreviation stand for, struggling to work it out in its entirity

 

[holmslaw]

-.

 

[holmslaw]

..

 

[333rocky333]

I cannot see why he is getting a hard time.

He has resolved the cable size issue,what he proposes (for the lighting) although it may not be the norm, afaik the design does not contravene the regs.
The feeds at the start of the runs, would be better than teeing in I think.

As he said, he may fit downlights and rather than put j/bs within the ceilings he simply wants to put them in the loft.

As a draughtsman he could draw up a detailed plan of wiring, so future fault finding (if any) would be easy.

He may also not want to chase out the wall and switch boxes for up to 3 cables

EB
The amount of j/bs does seem excessive could you not do some of the rooms 3 plate at the ceiling roses and just some at the j/bs if necessary.
Some of the work is also notifiable , kitchen, bathroom.

 

[holmslaw]

..

 

[333rocky333]

333rocky - every thing you say is a contradiction therefore there is no point in your statements !

Thanks

 

[edenbridge]

Hello again, everyone

Thanks again for all your comments. It's been a busy few days at The Project, but now I'm back at work I've got 'time' to respond.

First things first:

Some of the work is also notifiable , kitchen, bathroom.

I'm already aware of that, thanks, and have things covered.

The amount of j/bs does seem excessive could you not do some of the rooms 3 plate at the ceiling roses and just some at the j/bs if necessary.

Admittedly it's not very clear on the legend/key on my diagram, but some of the black blobs are roses, and others are JBs. There's a newer diagram below.

A new installation should have no joint boxes...
..It is NOT a loop in / loop out method at all, stop calling it that! You are proposing the old school and out dated JOINT BOX method.

The previous diagram could have been a little misleading, being stretched out like a London Underground map, but as I've mentioned the blobs were either JBs or roses.
I figured a ceiling rose is a joint box by another name, but I understand what you are saying. Obviously the fewer joints the better, and hopefully you'll approve of my latest approach.
We have finalised the type and position of most of the lights in the bedrooms, hall and lounge, but the kitchen and bathroom are still up for grabs, hence my preference to a JB until we decide.

The feeds at the start of the runs, would be better than teeing in I think.

After I uploaded my drawing I did think that might raise a few eyebrows. Again, the revised diagram hopefully rectifies this.

He may also not want to chase out the wall and switch boxes for up to 3 cables.

Quite right. Some of my switchplates are two-way, and some are even 3-gang. Despite "loop-in at the switch" being the preferred approach by most professionals, and there may be the opportunity to do that in some places here, I'd prefer all drops to switches to follow the same format, hence connections at the ceiling/loft.

The new diagram is below - I hope you'll all like it a bit better.

 

[holmslaw]

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