Lighting circuits wired in rings?

[devans]

Hi there. Realise this isn't really a DIY question but any help would be appreciated! I am currently studying surveying and have an exam coming up about services within buildings.

The person that wrote the notes has drawn diagrams and explained lighting circuits as if they were ring circuits (i.e. exactly the same as his diagrams for rings for sockets). During holidays, I have worked with an electrician and was under the impression that lighting circuits were only ever wired as radials. Is larger scale lighting wired differently and are lighting circuits ever wired in rings?

Thanks for your help

 

[Spark123]

I have only ever seen lighting circuits wired as radial. The more lights required, the more circuits installed normally.

 

[holmslaw]

..

 

[JohnD]

"The person that wrote the notes" has got it wrong.

Ask the lecturer why.

 

[333rocky333]

I recently read an article, that some commercial designers are now opting for RING lighting in order to use smaller cables for larger areas.

Not seen it done anywhere yet though

 

[mattylad]

from what I have seen lighting just gets wired.

A single T&E from the Cu then it splits off & goes all over the place.
It appears to be more like a bowl of spaghetti

It makes sense to wire it in a logical order be that radially or in a ring whatever current requirements are.

 

[lazygit]

In theory if you had 4 lamps of equal wattage wired in a ring, there will be no current flow in the cable between the second and third lamp.
So no real point in the cable being there unless the MCB for the circuit is too large for a radial.

I was told that rings were designed as a cheap solution to increase MCB size without a total rewire, during a time when copper was expensive and electricity demand was growing.

regards

 

[333rocky333]

In theory if you had 4 lamps of equal wattage wired in a ring, there will be no current flow in the cable between the second and third

Why would that be.

 

[dullSpark]

Only if the bulbs were evenly spaced, exactly the same construction and cable length on both sides.

 

[mattylad]

Does that mean we can run the 2nd & 3rd lamp for free

 

[dullSpark]

No, but you could save yourself buying that extra bit of cable!

 

[Click-Sure]

I've not only seen it but wired lighting circuits as rings when voltage drop becomes an issue.

How do you like them apples, discuss.

 

[mattylad]

What do the current regs say about wiring lighting circuits?

Would there be any problem wiring them in a ring?

 

[Click-Sure]

Neither the 16th or 17th say anything about wiring circuits used for lighting and if they should be radial or ring finals. The question i ask you is why would you need/want to outside of an industrial/commercial setting?

 

[mattylad]

Why would you want/need to what?
wire a lighting circuit?

Last time I looked residential houses have them too