Garage fused spur - modification/repair

[JohnW2]

I think ill just trial connecting the fuse up properly ...

Fair enough.

... and seeing if the saws melt the fuse.

They won't

I want to add a socket on the other side of the garage but for low wattage stuff, so itl look like this:

Fair enough. If you connect them to the load side of the fuse, you can (per regs) have as many sockets as you like - although, of course, the 'theoretical maximum' you could (should) draw across all the sockets would be 13A

If this fails and the fuse blows then ill extend the ring.

Fair enough - but, as above, that's not going to happen 9with your presently envisged loads). Of couyrse, if, in the future, you decide that you do want to service appreciably greater loads, then you would need to extend the ring.

I hope all goes well - which I'm sure itr will.

Kindest Regards, John

 

[JohnW2]

True - but, in terms of the OP's current requirements, a lot more work than is needed.

Kind Regards, John

 

[EFLImpudence]

True - but, in terms of the OP's current requirements, a lot more work than is needed.

True - if acceptable to limit to 13A, but not compared to extending the ring.

 

[JohnW2]

True - if acceptable to limit to 13A, but not compared to extending the ring.

Yes. I would personally say (and, in fact, I think you previously have more-or-less said this) that limitation to ~13A is reasonable for the OP's (current) situation. If not, although it depends to some extent on 'access', I'm not convinced that changing most of the existing wiring to 4 mm² would be less work than adding one bit of 2.5 mm² to 'extend the ring'.

Kind Regards, John

 

[sparkwright]

Im just concerned how ill identify which of the wires in the upstairs sockets is the redundant one to remove...

You don't need to worry about removing any upstairs socket cables.

If you try to extend the new garage ring, and bring another cable to the upstairs socket again, you can do a joint at this socket - and you won't need to mess about with another upstairs socket.

At the existing upstairs socket you would have:
the two original ring cables
the cable added last year
a new cable you will add to complete the garage ring.

At the socket you would connect one old ring cable and one of the newer cables in connectors or wagos within in the socket box.
and
connect the remaining old ring cable and the remaining newer cable directly to the socket.

***
At the garage you would carry on the newish wiring to go to the new garage socket you propose, and from there would be the new cable that you would have to take to the bedroom socket.

CHECK THIS FIRST:
1) Are you certain the bedroom sockets are protected by a 30 or 32 amp fuse or breaker?
2) Are you certain the newer cable IS 2.5mm2, and not 4.0mm2?

 

[JakeyBlee]

This isn't something I've come across - do 4mm spurs not need to be fused?

 

[JohnW2]

This isn't something I've come across - do 4mm spurs not need to be fused?

No, not in the sense you mean. All that matters is that the cable is adequately protected and (with the most common installation method) 4mm² cable is adequately protected by the 32A MCB protecting the ring circuit. After all, again assuming that common installation method ('Method C'), a 4mm² radial protected by a 32A MCB (and no other 'fusing') is perfectly OK.

Those who don't, or can't, think for themselves don't realise this, because it is not one of the examples of 'what can be done' given in the guidance in an Appendix of the Wiring Regs (BS7671) - which is probably why the use of unfused 4mm² spurs (supplying an unlimited number of sockets) is not common. However, if they understood the rest of the regs, they would hopefully realise that it was OK.

The only theoretical 'risk' of this that some people might fuss about is that it potentially allows a large load to be applied to one point of the ring, and IF that point is close to one end of the ring that could theoretically overload the cable of the short leg of the ring from there. However, exactly the same 'risk' exists if one has multiple sockets, or multiple 2.5mm² fused spurs, connected close to one end of the ring. In all cases, the way to avoid any such 'risk' is the same - namely not to install multiple sockets, multiple 2.5mm² spurs or one 4mm² spur close to one end of the ring!

Kind Regards, John