Socket on ring circuit?

[tah06]

I'm hoping to create a new socket in my internal garage by creating a spur from the existing socket which has existed since day 1 of my 2014 property. I've been following my trusty 2006 DK DIY book and it suggests that i must first check if the socket is on a ring main circuit or is the intermediate outlet on a two outlet spur.

The existing socket is part of the downstairs circuit breaker which I can isolate along with the other downstairs sockets. The socket has 2 cables in it and as i don't have any technical equipment, the book suggests that I test the circuit type by disconnecting the 2 live cores, separate them and then checking the other downstairs sockets. The book says that if the socket is on the main circuit all other downstairs sockets should be dead. When I do this though, all other downstairs sockets continue to work. Is the book right, should I be concerned and can I still run a spur from this socket?

 

[ericmark]

Book wrong if it says that, on a ring final one break in the circuit and all sockets still work.

 

[tah06]

Maybe I've misunderstood the book, but here it is

 

[terryplumb]

Chuck the book away ,the above is very wrong.
To establish what the cables are requires testing with a suitable test instrument .

 

[securespark]

That applies to the US code, surely?

 

[ericmark]

As @securespark says, we have radial finals, ring finals, and spurs, a fused spur is really a radial final but you can't in English have a final final so called a fused spur, with ring finals we always have a 30 or 32 amp overload (fuse or MCB) but with a radial it could be any size from 16 amp to 32 amp, and could be 2.5 mm² or 4 mm² or 6 mm² with a ring final the cable must be able to take 20 amp, so in the main 2.5 mm² is used, it was 7/0.029 which was slightly thicker, and with mineral cable it can be smaller but unlikely to find mineral in a domestic.

As an electrician I would test if a ring or not when the circuit is dead, the two line conductors will show connected together using a multi-meter. I prefer a meter like these as since amps is not measured with leads, you can't make the potentially fatal mistake of leaving on amps when trying to measure volts and causing ionisation of the atmosphere. But since your testing dead no chance of that anyway.

But only the UK and ex colonies use ring finals, so only UK books will explain how to work out if the socket is on a ring final, radial final, or spur.

 

[SUNRAY]

Maybe I've misunderstood the book, but here it isView attachment 282098

I struggle to actually interpret what has been written there, what is 'opposite bottom'?

 

[Adam_151]

I presume a drawing is provided on the opposite leaf (which is out of frame in his image) of the two-page spread and is located at the bottom of the page

 

[SUNRAY]

I presume a drawing is provided on the opposite leaf (which is out of frame in his image) of the two-page spread and is located at the bottom of the page

That's exactly what I assumed is the case too.

 

[JohnD]

Maybe I've misunderstood the book, but here it isView attachment 282098

Is it an American book?

Are you in America?