Loft light cables

[APE37]

Hi guys, quick question
looking at getting around to installing a loft light at my sisters house and the board is 16th edition lighting on non rcd side. Cables will be clipped to wood work but 1 foot and half roughly will be going between joists to landing light. In this bit it is boarded and I was thinking about leaving on non rcd side, but thinking as the joists are about 75mm do I need to put on rcd side? As I look at on site guide it states cables passing through joists are to be plus 50mm and cables in walls or partitions need to be 50mm plus but as I am running between 2 joists ina ceiling and not passing through any joists to landing light do you think this needs rcd protection as the way I interpret it there are 2 sets of rules for cables in wall and other in ceiling and the rules don't state in a ceiling if rcd is needed when cables run along joist. Or should I take the plus 50mm rule when cable I talked in wall or partition?
Sorry for a silly question but looking to do the best way.
Cheers
APE

 

[richy3333]

Sounds like you've answered your own question?

 

[Octopus]

A ceiling is not a wall IMHO so no RCD needed.

 

[APE37]

Hi there,
thanks for responses. I am of the opinion that it don't need rcd protection, as Murdoch has stated it ain't a wall/ partition, and The other rule states about cables passing through joists, which I won't be doing, but as I want to use this as my minor for reassessment, i am just looking to see what others think. Don't want t get into trouble for it. Maybe a call to scheme provider is needed to clarify?
Thanks in advance if anyone else has anything they would like to add
all the best
APE

 

[Guest77]

Who cares about the rules, whack it up there, just get on with it lol.

 

[APE37]

Hi guys,
just a quick one to say I got In contact with my scheme provider's tech line and they confirmed that as I am not carrying work out in a wall and that I am not drilling through joists, it can stay on non rcd side. Just thought I would let you know the follow up and maybe help others that may need this answer in the future, as I felt it was a bit of a grey area.
any way I would just like to say thanks to all who answered, I thank you all.

regards
APE

 

[Octopus]

Hi guys,
just a quick one to say I got In contact with my scheme provider's tech line and they confirmed that as I am not carrying work out in a wall and that I am not drilling through joists, it can stay on non rcd side. Just thought I would let you know the follow up and maybe help others that may need this answer in the future, as I felt it was a bit of a grey area.
any way I would just like to say thanks to all who answered, I thank you all.

regards
APE

That bit is carp if you are working above a ceiling! I'm guessing you are an Elecsa or NICEIC member

 

[MikeL1]

Electrical installation gone mad, get on with it.

 

[Johnuk]

as above lol

 

[J.C.E]

just do it mate- if you feel it needs rcd protection- could always just supply the light with a rcd fcu

 

[sparksburnout]

I think this raises an interesting point. Apart from all the above prattling about is it a wall or is it a ceiling and is it 50mm from this that or the other, is it not actually a good idea to RCD protect the lighting circuit? Now, I realise there is a problem with blowing bulbs tripping RCD's and knocking off other circuits (although I have never actually experienced it in my own house to be honest), but surely there is more of a danger with people changing bulbs, bulbs possibly breaking, and even sticking their fingers in lamp-holders intentionally or accidentally than anything else? I recently had a fault where a builder had re-boarded a ceiling and managed to screw through a cable that was laying on top of the plasterboard under insulation, seems to me that it would be a good idea to protect cables exactly the same as if they were in a wall? Would the benefits not outweigh the possible drawbacks? Just a thought.

 

[Risteard]

I'm not sure why anyone thinks it is a grey area. Above the ceiling has never been the same thing as in a wall, nor will it ever be. Ceilings and walls are different things.

So it is very, very clear in BS7671 that RCD protection is not required just because something is installed above a ceiling. (Is anyone likely to hang a picture from the ceiling?!?!?!)

As for whether it is a good thing to install RCD protection when not needed, it isn't necessarily.

RCDs can be avoided in most of a domestic installation if the client is willing to pay for it (e.g. flush steel conduits) - but usually RCDs are the more cost effective way of achieving compliance with BS7671.

 

[Midwest]

So it is very, very clear in BS7671 that RCD protection is not required just because something is installed above a ceiling. (Is anyone likely to hang a picture from the ceiling?!?!?!)

S**t happens; http://www.electriciansforums.co.uk...um/107352-screw-through-lighting-circuit.html

 

[Deleted member 26818]

It's not so much a question of it being required, more that it is not deemed adequate.
Additional protection is required for cables above ceilings and below floors, where the cables are run through joists.
The theory being: If a screw or drill is pushed through into the void between joists, any cables will just be moved aside.
Cables run through joist will be trapped in place and the screw or drill will penetrate.

 

[APE37]

Hi guys,
i think the tech guy was getting at, as the joists was 75mm the cable would not have 50mm plus from top and bottom to protect cables from fixings of floor and ceiling. If it was a bigger joist and plus 50mm can be achieved, then no rcd is needed. As I have not ran my cable through a joist, it can stay on non rcd side. As spinlondon said cables need to be spaced away from fixings and if it is between joists chances are it will move away, in a joist, it can't. Also as it is the only source of light, if I put it on rcd side and another circuit trips the rcd and some one is in the loft , they would be at risk of an accident. I could put the circuit on an rcbo but the unit is a bit strange and I don't think it has enough room to fit one in.
thanks for all the help, Ideas and advice, I am really grateful.
all the best
APE