Clarification on the Regs...

Thomas Connolly · Jan 23, 2019

Hi Chaps,
This may be something simple but I'm not sure I understand it correctly.

Regarding spurs...

"The total number of Fused spurs is unlimited but the number of non Fused spurs should not exceed the total number of socket-outlets and items of stationary equipment connected directly in the circuit"

So I understand that say for example, on a ring, there are 4 double sockets, you can only spur once off of each socket of it is unfused.
The confusing part for me "the total number of Fused spurs is unlimited"
Does this mean that out of the hypothetical four double sockets on the the ring, you could pick one double socket, add a Fused spur, then have another Fused spur from that one, and then another Fused spur from that one etc etc etc
Or does it mean that from one socket outlet, you can add multiple fused fused spurs (providing that you could get all the wires in safely)

Thanks as always .

Nebu1a · Jan 23, 2019

You cant have a spur off of a spur off of a spur but you can have as many fused spurs taken from the ring itself. Each fused spur will only carry a load of 13amps max so the cable cannot become overloaded. Thats the way I read it.

Cid · Jan 23, 2019

Maximum one fused unit per socket in the ring. From the fused unit you can have unlimited number of sockets

Deleted member 26818 · Jan 23, 2019

I suggest you forget about the number of spurs being limited to the number of existing sockets or how many FCUs are used.
Just look at the diagram for a RFC in Appendix 15.

buzzlightyear · Jan 23, 2019

[ElectriciansForums.net] Clarification on the Regs...

appendix 15.

Thomas Connolly · Jan 23, 2019

I did look at it but was a bit baffled can understand it much more now.
Just needed some simpler wording for me to get my head around it!
Reading through the book religiously in an attempt to get a grasp, and keep a grasp of it all.
This forum is an absolute god send .
Thanks .

littlespark · Jan 23, 2019

Thomas Connolly said:
"the total number of Fused spurs is unlimited"

As is the number of points on the rfc is unlimited... so if each point on the ring can have a spur off....

In practice, you would never have 4 spurs off your hypothetical 4 double sockets on your ring.

Deleted member 26818 · Jan 24, 2019

Thomas Connolly said:
I did look at it but was a bit baffled can understand it much more now.
Just needed some simpler wording for me to get my head around it!
Reading through the book religiously in an attempt to get a grasp, and keep a grasp of it all.
This forum is an absolute god send .
Thanks .

If you start at the top of the ring, and go anti-clockwise, the first thing you come to is a spur taken direct from the ring.
No socket, no FCU.
As you can see, you aren’t restricted to only taking spurs from sockets, it’s just easier.
You don’t have to use an FCU, though using one means you can have more than one socket on the spur.

AndyL · Jan 24, 2019

littlespark said:
As is the number of points on the rfc is unlimited... so if each point on the ring can have a spur off....

In practice, you would never have 4 spurs off your hypothetical 4 double sockets on your ring.

Not entirely true, you may have a RFC with NO sockets at all and only fused spurs, such as one feeding kitchen appliances

Pete999 · Jan 24, 2019

Thomas Connolly said:
Hi Chaps,
This may be something simple but I'm not sure I understand it correctly.

Regarding spurs...

"The total number of Fused spurs is unlimited but the number of non Fused spurs should not exceed the total number of socket-outlets and items of stationary equipment connected directly in the circuit"

So I understand that say for example, on a ring, there are 4 double sockets, you can only spur once off of each socket of it is unfused.
The confusing part for me "the total number of Fused spurs is unlimited"
Does this mean that out of the hypothetical four double sockets on the the ring, you could pick one double socket, add a Fused spur, then have another Fused spur from that one, and then another Fused spur from that one etc etc etc
Or does it mean that from one socket outlet, you can add multiple fused fused spurs (providing that you could get all the wires in safely)

Thanks as always .

Take a good look at Appendix 15 , it gives you pictorial and written examples of what and how to connect to a Ring Final Circuit (RFC) you can spur off by means of a Junction box if you wish, a Spur is not limited by being connected to an existing socket outlet which forms part ot the RFC.
The Regulation covering this (sorry I only have the 17th edition it may be different in the 18th) is 433.1.204.
A spur cant also be use to supply an item of fixed equipment providing can meet the requirements of the stated Regulation ie a recommendation that equipment at 2 KW and above is given it's own dedicated circuit, things to avoid are Immersion heaters, Space heating etc.
I believe someone else has mentioned App 15, it's not really that hard to understand and the diagram goes a long way to help in the understanding.
Hope this helps.
Edit, with the inclusion of AFDs we may eventually see the demise of RFCs in favour of Radial circuits, protected by either, 20 A or 32 A OCPDs using 2.5mm2 and 4mm2 cable for 20A and 32A respectively.

littlespark · Jan 24, 2019

AndyL said:
Not entirely true, you may have a RFC with NO sockets at all and only fused spurs, such as one feeding kitchen appliances

I agree.
I used the word “points” on the ring. The mention of sockets was referring to an earlier post

Blissof89 · Jan 24, 2019

Are we still allowed to take a spur direct from the OCPD? I seem to remember specifically being told it was allowed in the 16th but regs seem to make no mention of it anymore.

Pete999 · Jan 24, 2019

Blissof89 said:
Are we still allowed to take a spur direct from the OCPD? I seem to remember specifically being told it was allowed in the 16th but regs seem to make no mention of it anymore.

Yes from anywhere on the RFC