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Unfused Spurs from a Ring Circuit

Horace Charles

I am not an electrician but have electrical knowledge and some knowledge of ring circuits and the wiring regulations. I would like to understand from expert readers some points about an unfused spur from a ring circuit.

As I understand it the regs say that an unfused spur in 2.5mm cable from the ring circuit may feed only one single or twin (or triple?) socket OR one fixed appliance via a Fused Connection Unit (FCU).

BUT if instead of feeding a single fixed appliance, that FCU fed several sockets, would such an arrangement comply with the regulations. The combined maximum current to those sockets would of course be limited by the FCU 13 amp fuse and RCD protection is assumed at the Consumer Unit.

This limited current capability of sockets fed in this way might be restrictive, but might be OK if low current loads are connected to them e.g TVs, computer power supplies, electric armchairs etc.

I would like to understand if such an arrangement would be feasible before I call in a qualified electrician to quote for it. The reason for asking is that it would allow the provision of surface mounted sockets thus avoiding the need for disruptive cable chases in the wall.

Thanks for any feedback you may offer

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    Horace Charles said:
    As I understand it the regs say that an unfused spur in 2.5mm cable from the ring circuit may feed only one single or twin (or triple?) socket OR one fixed appliance via a Fused Connection Unit (FCU).

    Correct.

    Horace Charles said:
    BUT if instead of feeding a single fixed appliance, that FCU fed several sockets, would such an arrangement comply with the regulations. The combined maximum current to those sockets would of course be limited by the FCU 13 amp fuse and RCD protection is assumed at the Consumer Unit.

    Yes, that is also permitted. Appendix 15 says, "Spur using an FCU not connected directly to the ring The number of socket-outlets supplied from a fused connection unit is dependent upon the load characteristics, having taken diversity into account."

    I reckon that a single desk needs 4 double sockets.

    Or you can just daisy chain several 4 or 6-way trailing sockets. ;-) 

  • 0 in reply to Chris Pearson

    Thanks for your reply. I assume by trailing sockets you mean extension leads?

  • 0 in reply to Horace Charles

    Yes, the ones with 4 or 6 sockets in a row. Don't forget your 2-way adapters as well.

    Now, please note that this is very much tongue-in-cheek and not recommended. When I were a lad, you would probably have had a lamp (with a filament); you might have had a fan; and I suppose at a pinch, a wireless set.

    Nowadays, 'puter and a printer; broadband router; perhaps not a cordless landline anymore; and umpteen chargers, all at only a few watts each (except the printer).

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  • 0 in reply to Horace Charles

    Yes, the ones with 4 or 6 sockets in a row. Don't forget your 2-way adapters as well.

    Now, please note that this is very much tongue-in-cheek and not recommended. When I were a lad, you would probably have had a lamp (with a filament); you might have had a fan; and I suppose at a pinch, a wireless set.

    Nowadays, 'puter and a printer; broadband router; perhaps not a cordless landline anymore; and umpteen chargers, all at only a few watts each (except the printer).

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  • 0 in reply to Chris Pearson

    In reality, modern computers don't take much power. Gaming machines may be several hundred watts, but laptops much less.

    During lockdown, I had a 5A rated extension lead (with a 5A fuse in the plug) powering a 4-way and a 3-way extension lead, for my home computer and company laptop, plus all their peripherals.

    Nothing bad happened.

  • 0 in reply to Simon Barker

    Thanks for your feedback. I understand your point about today's devices being relatively low current demand items.  That was my thinking from the outset.

    But I can see from previous responses that electricians would prefer to add sockets by connecting them in an extended ring circuit.

    I suppose there will always be the possibility of a future owner of the house, who is not aware of the 13 amp FCU limit, plugging electric heaters in to the sockets if the central heating fails ?

    Thanks again for your feedback 

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