spur of a spur

[EFLImpudence]

So my question is, is there anything against the regs which prohibits me from downgrading upstairs ring to 20A?

No, that would be fine.

 

[calum63]

No, that would be fine.

Thank you, I will downsize the breaker to 20A. Its much easier than messing around with fcus.
thanks again

 

[jg321]

Thank you, I will downsize the breaker to 20A. Its much easier than messing around with fcus.
thanks again

And also remove the "return" leg of the ring to make it a radial. To my knowledge, you shouldn't have a ring final with a 20A fuse/breaker.

 

[JohnW2]

And also remove the "return" leg of the ring to make it a radial. To my knowledge, you shouldn't have a ring final with a 20A fuse/breaker.

There's no reason why one can't, but there would be very little point.

However, looked at the other way around, if the 'return leg' is already there, there's no real point in removing it.

Kind Regards, John

 

[jg321]

There's no reason why one can't, but there would be very little point.

However, looked at the other way around, if the 'return leg' is already there, there's no real point in removing it.

Kind Regards, John

Oh, I stand corrected then. I thought the the regs explicitly stated it. I would personally remove the return leg to make it more "standard", although as you say, there's no requirement to do so.

 

[JohnW2]

Oh, I stand corrected then. I thought the the regs explicitly stated it.

No, the regs merely say that one can have a circuit wired in cable with a CCC as low as 20A protected by a 30/32A fuse/MCB (which normally would not be allowed) IF it is a ring circuit.

There's nothing in the regs that say that one can't add extra ('unnecessary') cable to a circuit which is already compliant (which a 20A 2.5mm² radial will be)

I would personally remove the return leg to make it more "standard", although as you say, there's no requirement to do so.

Fair enough. However, as I said, you would gain nothing and, for what it's worth, would lose the CPC redundancy.

Kind Regards, John

 

[John D v2.0]

Also if you remove the return leg there's a chance in a big ring that the last socket before the removed leg might not be up to spec due to too much cable between it and the mcb. You would be better if you must remove a link to remove one in the middle

 

[EFLImpudence]

Which is the return leg?

 

[JohnW2]

Also if you remove the return leg there's a chance in a big ring that the last socket before the removed leg might not be up to spec due to too much cable between it and the mcb.

Although theoretically true, it would have to be a pretty long ring for that to become an issue, particularly after the OPD had been reduced to 20A.

You would be better if you must remove a link to remove one in the middle

If I understand you correctly, would that not result in the path length to the 'last socket' on one of the legs being even longer than if one simply removed the 'return leg'?

Kind Regards, John

 

[JohnW2]

Which is the return leg?

You make me realise that I was thinking of a different thread, in which there was a string of sockets with a 'return leg' running back past all of them to the CU - but I'm not sure that makes much difference to what is being said in this thread.

Kind Regards, John

 

[John D v2.0]

Although theoretically true, it would have to be a pretty long ring for that to become an issue, particularly after the OPD had been reduced to 20A.

Agreed but I was thinking about volt drop


(((I said:: remove from the middle)))

If I understand you correctly, would that not result in the path length to the 'last socket' on one of the legs being even longer than if one simply removed the 'return leg'?

Depends on the lengths of the legs, I'm assuming the return leg isn't just coming back exactly the same way! When I say the middle, read that as the middle in terms of cable length not in terms of number of accessories

 

[JohnW2]

Agreed but I was thinking about volt drop

Fair enough. Mind you, with a 20A circuit, even if the whole 20A is at the very end, one could have about 32 metres of 2.5mm² and keep within the 5% VD guideline, which is probably more than most radials in 'ordinary' houses.

(((I said:: remove from the middle))) ... Depends on the lengths of the legs, I'm assuming the return leg isn't just coming back exactly the same way!

As I recently admitted, I was actually thinking of a different thread in which the return leg was "coming back exactly the same way.".

When I say the middle, read that as the middle in terms of cable length not in terms of number of accessories

Yes, if one splits it somewhere around the middle of the cable length, that would be the ideal - but, as I said, whether one thinks about Zs or VD, it's probably unlikely (in an 'ordinary house') that there would be a problem with a 20A circuit, no matter where one split it.

Kind Regards, John

 

[calum63]

Hi, All I propose to do is downsize the mcb to allow me to take the feed from the spur to the attic as well as comply with wiring regs, keep it all above board, I know some people wouldn't give this a second thought and carry on regardless without giving a rats arse about regs. I like to do things properly.

With regards to the ring I fail to see any point in removing one of the legs,I'm not sure what that will achieve?
thanks

 

[JohnW2]

With regards to the ring I fail to see any point in removing one of the legs,I'm not sure what that will achieve?

As I have said, I agree.

Kind Regards, John

 

[jg321]

It sounds like I may have thrown a spanner in the works by mentioning that, so feel free to ignore me! Leaving the ring intact appears perfectly acceptable, and even has some advantages (CPC redundancy!).

Jon