Ring Final Circuit - spurs only

[John-SJW]

I read that it is against the regs that a ring final circuit cannot be just a ring with with spurs off it. In short, a ring must have sockets on it which double up as junctions. I find that hard to believe.

 

[davesparks]

A ring can't have more unfused spurs than it has sockets on the ring.
So if there are 10 sockets on a ring then the maximum number of unfused spurs you can have is 10.

Spurs do not have to be taken from sockets, they can be taken from a suitable joint box or from the origin of the circuit.


As always the above refers to the 'standard circuits' as described in the regulations and supporting publications. If you wish to design your own non-standard circuits then you are free to do so, however you would need to fully document the design (as a courtesy to anyone else who has to work on the installation, as defense should anything go wrong, as defense when an EICR is carried out and the non-standard design is flagged up, etc etc)

 

[John-SJW]

A ring can't have more unfused spurs than it has sockets on the ring.
So if there are 10 sockets on a ring then the maximum number of unfused spurs you can have is 10.

So, a ring can be just a ring of cable - in effect a busbar. Then on this cable j-boxes with spurs off that.

 

[davesparks]

So, a ring can be just a ring of cable - in effect a busbar. Then on this cable j-boxes with spurs off that.

No, it can't, not as a standard ring final circuit.

As I said, a ring can only have as many unfused spurs as it has sockets connected to the ring.

On your ring of cable with joint boxes, if you intend it to be a standard ring final circuit, you cannot have any spurs as you have no sockets on the ring.

 

[mainline]

So, a ring can be just a ring of cable - in effect a busbar. Then on this cable j-boxes with spurs off that.

You can have a ring circuit and have no socket outlets at all if you want.

 

[littlespark]

What would lead you to design a circuit like this?

If you can get one cable to a socket, then you can get two.
It has no financial benefit, as the cable saving is countered by joint boxes and time making those extra joints.
The extra joints also add another point of possible faults.

In technical terms…. This is how a standard socket is. The joint is the terminals on the back of the socket… the “spur” is the internal metalwork between the terminal and the contacts for the plug pins.

 

[DefyG]

Perhaps there is more to JSJW's design than he is letting on, but per post #6 what would be the point? Just as easy to accommodate sockets into the RFC!

 

[John-SJW]

A dedicated ring for only heavy appliances, hard wired in comes to mind. Sockets on a separate ring.

 

[John-SJW]

Just a thought on this. A ring with jboxes only. The jboxes supply only one socket via a cable approx 2 to 3 metres long. Big saving on cable.

 

[westward10]

Just a thought on this. A ring with jboxes only. The jboxes supply only one socket via a cable approx 2 to 3 metres long. Big saving on cable.

What you save on cable you probably lose more on the junction boxes.

 

[John-SJW]

If this situation arose is it legal? A ring with only jboxes is the point. Or the actual ring cable with no sockets on it.

 

[mainline]

If this situation arose is it legal. A ring with only jboxes is the point.

You can have a ring with only j boxes if you want, and yes it's legal as you put it.

 

[westward10]

If this situation arose is it legal? A ring with only jboxes is the point. Or the actual ring cable with no sockets on it.

Do the junction boxes cost more than the cable you are saving?

 

[John-SJW]

Please try and focus on the point i was making.

 

[westward10]

Just a thought on this. A ring with jboxes only. The jboxes supply only one socket via a cable approx 2 to 3 metres long. Big saving on cable.

In #9 you stated big saving on cable.