Is this considered ring in general and/or by the regs?

[Octopus]

This is how it was described to me. I don't know how do you call a ring with one point and radials from that point!?
He says these junction points will be accessible - I haven't been there yet so I don't know if it will be in a floor box or somewhere else!

Scary stuff. Best you go and see this first hand......

 

[JuniorSparky]

I don't know. This is why I was asked to fix it!

Yes, I will go first to take a look before I start. He's far from me, so I'm getting as much info as I can before my visit!

 

[Deleted member 26818]

Sounds like a Spider ring or radial.
If it covers more than one floor, most likely a ring.
Don't take any notice of the one spur per point myth, as it's just a myth.
Spurs can be taken from any point on a ring, including the CU, as shown in Appendix 15.

 

[davesparks]

Don't take any notice of the one spur per point myth, as it's just a myth.
/QUOTE]

When did that change? When I was an apprentice we were taught that the number of spurs from a ring cannot exceed the number of points on the ring.

 

[Hellmooth]

1 unfused spur per socket and unlimited per fused spur, or am I on the 19th edition?

 

[davesparks]

1 unfused spur per socket and unlimited per fused spur, or am I on the 19th edition?

You have to be careful with the wording. One unfused spur per socket implies that spurs can only be taken from a socket.
Wheras what is meant is that you cannot have more unfused spurs than you have points on the ring.

 

[Lucien Nunes]

I'm not sure I'd want every socket in the house to be on a fused spur with a 13A fuse upstream of it. Daisy-chaining points behind a fused spur avoids any question of cable overload but it's not good practice and doesn't make the CCC of the ring available throughout which is the main idea.

I'm interested why they put a stop to that method Dave? It would still have the same balanced current across the two legs of the supply, topographically it's still a ring final in that respect even to the point that if the junction boxes were sockets it would be compliant.

I've always though that the main point of this is to encourage installers to run the ring around most of the floor area of the premises. Otherwise there might be all sorts of haphazard layouts, e.g. a small ring around a central area with spurs heading out to do most of the work - a kind of extreme spider ring - or a long thin ring along one side and spurs across. There was a period when old radial installations were being modernised with rings and the temptation would have been to re-purpose the radials as spurs. This defeats the main advantages of the RFC - to enable full capacity to be used almost anywhere and to allow easy expansion by breaking into the ring.

There is also the aspect that if you use actual points at the spur tap-off locations, they will attract some of the loading from the ends of the spurs.

 

[Deleted member 26818]

Spider rings comply, but are rather impractical.
Spurs cannot be taken from existing sockets, as they are already Spurs.
They involve JBs invariably under floor boards which since the advent of fitted carpets are virtually inaccessible, and especially so now with the trend for laminate flooring.