Lighting Circuit.

[kai]

Is there any reason why one cannot wire a lighting circuit in a Loop circuit, with both ends of the 1.5.sq.mm. cable being joined to the B6amp lighting MCB? (i.e. in a ring circuit fashion, but with 1.5. sq.mm. cable)?

Surely this method can give better earth loop resistance performance, and possibly better lighting performance, due to less voltage drop.

 

[ryanj]

Pretty un-orthodox method, but there isn't anywhere that says it can't be done.

As for Earth loop impediance, I don't think it'll make any significant difference, same goes for voltage drop.

The maximum voltage drop for a radial would be 174mV per meter, dropping to 43.5mV per meter on the ring circuit, I don't think you'll notice any better lighting.

A reason against though, any work done to the installation in the future by a careless electrician, could casue havoc, as he wouldn't expect it to be installed in a ring fashion.

As I understand, the only reason ring circuits were used, were to save on cable during the second World War.

 

[kai]

I'd label the B6 MCB as "Downstairs/Upstairs/Wall LIGHTING-RING" though and the two cables entering the B6 MCB ought prompt the electricians in the future.

 

[ryanj]

What are your reasons for wanting it in a ring arrangement?

And why does it cover downstairs and upstairs?

A fault on an upstairs fixture, could leave the whole house in darkness.

 

[dingbat]

Calling it a ring probably won't make it any clearer as many non-electricians refer to all circuits as rings anyway. It will just look like two radials with a common origin and, as has been mentioned, might lead to confusion.

Ring circuits are peculiar to UK domestic socket circuits and there is a degree of lobbying to make all circuits radials, as they are in many parts of the world.