Lighting Circuit

T

Terry2sheds

Just looking at all Wiring Diagrams in FAQs Sticky.

All show supply to next light, but I've discovered a light unit in loft that has no supply out. I know this could be last on circuit, but should it not have a return wire to complete the ring?

If it should, is it ok just to complete by installing a return wire to the previous fitting in the circuit?
 
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Does anyone give a straight answer on here?

I hadn't seen this layout, but if I had I think I would still have asked the question.

Are you saying that lighting circuits don't complete the ring?
 
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I must admit that i always thought that all circuits were of the Ring Final type shown.

The Lighting circuit in question is in an old semi, which has been re-wired, probably in the last 10 years. If this circuit is of the radial type, what size should the wire be?
 
Thanks Peter.

Sorry I miunderstood, thought you meant that all circuits had to have cable size upped on radial circuits.
 
I've never know lighting circuits to be wired on anything other than "radial" type circuits.

Terry, there could be many lights in the house with only a feed in (no feed out). Depends how it was wired.

The size of the cable depends on the protective device size, whether or not it is adversely affected by

a) ambient temperature - norm is 30 deg C
b) thermal insulation - the cable only has to look at this stuff and it creases at the knees
c) whether it is grouped or touching other circuits
d) or protected by BS3036 fuses (white dot, re-wireable type)

If neither a-d are a factor then:

For a 5 or 6 amp device you can use 1.0mm sq (assuming the lighting load does not exceed 1,150W or 1,380W respectively.

If you have a 10A device and assuming your lighting load does not exceed 2,300W then use 1.5mm sq.

But if you may increase the demand later by adding more lights just use 1.5mm sq.
 
The ring final is a UK aberration. Most electrical circuits in the world are radials, but we introduced the RF (so I have always udnerstood) as a wartime wheeze to save copper - instead of runing several radials, one ring meant less copper used and as long as the ring goes end-to-end properly meets the power capacity requirements. On some of the more technical web forums you'll find the occasional discussion about whether the RF is good or bad and whether it should be done away with.

PJ
 
Terry2sheds said:
I know this could be last on circuit, but should it not have a return wire to complete the ring?
Click to expand...
If you did that it wouldn't be the last one on the circuit any more - it would be the first one. Then what?
 
Peter,
Reason for the duplicate post is that I realsied immediately that I posted in the wrong place, or thought I had, and not being able to move it I re-posted. A no -no I now know.

Answer was fine from you first time, but then I started to get replies to alternative post.

Ban - All Sheds, Not sure what you mean by your post getting a thumbs down, I didn't, so as for the Immature Idiot, please look elsewhere.
Your comment regarding it now being the first, what then? well it would be a ring wouldn't it, my initial understanding?

Overall though this forum would benefit from less sarcasm, people only go to the trouble of posting on here because they don't know and want answers. You experts obviously enjoy giving answers, so why get sarcy or exasperated when questions are asked.

I genuinely thought that all circuits were ring final and having asked the question, have found all the info that came back extremely helpful and I promise not to ask again.
 
Are you another troll ?
Click to expand...

ricicle

If you took a moment in your busy life to look at the posting history, maybe you could have saved yourself this comment,

I have been acquainted with bas since he frequented the screwfix forum a number of years ago.
 
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