Spur off a spur

[Jon Bridges]

Is it an accepted practice to spur off a spur on a ring if the first spur has been run from 4mm cable. I've never done it as always been told to spur off a spur was a definate no-no, but is it ok with 4mm?

 

[telectrix]

I would assume that as long as you take your new spur feed from the supply side of the existing spur and ensure that it is correctly fused for the equipment it feeds, then it's perfectly OK.

 

[Hawk81]

no it is not ok to spur off a spur no matter what cable size. the regs state this.

 

[wallyanker]

You can take 1 unfused spur from each socket on a ring, eg, 10 sockets on ring can have 10 unfused spurs, 1 from each socket.

You can then take a FUSED spur from an unfused spur, this is fine, and if you wanted take another FUSED spur from the previous FUSED spur.

As long as each spur is fused then the regs allow it, as the cable between the spurs is protected.

 

[Amp David]

This is news to me.

 

[Deleted member 9648]

This is news to me.

Have a look at appendix 15 in the BRB.

 

[ezzzekiel]

You can then take a FUSED spur from an unfused spur, this is fine, and if you wanted take another FUSED spur from the previous FUSED spur.

what is protecting the additional cabling between unfused and fused spur.

1 spur per outlet or 1 fused spur with as many outlets as required after the fused unit

 

[wallyanker]

what is protecting the additional cabling between unfused and fused spur.

1 spur per outlet or 1 fused spur with as many outlets as required after the fused unit

Your right, swap the unfused spur for a fused one is the correct way.

 

[Amp David]

Thats what threw me off track.

Fused spur first then your additional outlets

 

[Deleted member 9648]

Actually while a spur from a spur off a ring ,even wired in 4.0mm would not comply with the requirements for ring circuits, and hence should not be done,in practice it should not be a problem.Given that a radial wired in 4.0mm and fused at 32A can supply an unlimited number of sockets you would in effect be spurring a radial from a ring circuit fused at 32A,there would seem little difference.

 

[Amp David]

Have a look at appendix 15 in the BRB.

Yes, but it doesn't show a fused spur coming from a unfused spur does it?

 

[Deleted member 9648]

Yes, but it doesn't show a fused spur coming from a unfused spur does it?

Yep....misread the post from wallyanker.

 

[Amp David]

Actually while a spur from a spur off a ring ,even wired in 4.0mm would not comply with the requirements for ring circuits, and hence should not be done,in practice it should not be a problem.Given that a radial wired in 4.0mm and fused at 32A can supply an unlimited number of sockets you would in effect be spurring a radial from a ring circuit fused at 32A,there would seem little difference.

Only problem then is if one leg of the ring fails, then you have a 2.5 with a 32amp breaker/fuse

 

[Deleted member 9648]

Only problem then is if one leg of the ring fails, then you have a 2.5 with a 32amp breaker/fuse

Under those circumstances you would end up with two 2.5mm radials fused at 32A regardless of whether anything is spured off or not......although off course a 4.0mm radial tacked on would add to the problem.

 

[Risteard]

It's not only about overload though. It also has to do with unbalancing the ring.