Should ring main live return to same MCB?

[SUNRAY]

The whole point about my post is that a ring final spur may be made using 2.5mm cable and it may be derated to around 14A by the conditions its in and it may have a double 13A socket on the end of it

No it may not.

and there may be a 3Kw device pluged into each socket. And yes I have seen exactly this too many times and earnt a lot of money correcting the resulting damage.

And the reason you see damage is because it's not in compliance with the wiring regulations.

NO
Thats all in the regs and may be fitted in every other house in the country.

It may be commonly encountered, but it is NOT in the regulations.

Appx 15 states that you can fit a 2.5 unfused spur to a 32A Ring Final circuit, feeding one outlet. Or an FCU can be used to supply several outlets wired in min. of 1.5mm² T&E.

On a 20A Radial Final circuit, a minimum of 2.5mm² T&E must be used.

On a 32A Radial Final circuit, a minimum of 4.0mm² T&E must be used.

HOWEVER, an unfused spur can be taken from any point in the circuit in 2.5mm² (including at the origin of the circuit), providing it feeds only one single or twin outlet.

It seems there is a difference of opinion on the interpretation of the regs.

Simple question

Is it permissible, within the regs, to install a DSO using a 2.5mm T&E spur on a ring final without any additional protective device?

 

[Chri5]

Is it permissible, within the regs, to install a DSO using a 2.5mm T&E spur on a ring final without any additional protective device?

Yes it is, but note the word spur, one DSO only and the obvious fact that the spur will not be a significant distance from the ring socket the spur is taken from.

 

[ban-all-sheds]

It seems there is a difference of opinion on the interpretation of the regs.

No.

Simple question

Is it permissible, within the regs, to install a DSO using a 2.5mm T&E spur on a ring final without any additional protective device?

Yes, but not if the cable is seriously de-rated because of the way it's installed, which is what you were suggesting.

 

[SUNRAY]

Is it permissible, within the regs, to install a DSO using a 2.5mm T&E spur on a ring final without any additional protective device?

Yes it is, but note the word spur, one DSO only and the obvious fact that the spur will not be a significant distance from the ring socket the spur is taken from.

It seems there is a difference of opinion on the interpretation of the regs.

No.

Simple question

Is it permissible, within the regs, to install a DSO using a 2.5mm T&E spur on a ring final without any additional protective device?

Yes, but not if the cable is seriously de-rated because of the way it's installed, which is what you were suggesting.

Thanks for the relpies.



A very recent job was a 3month old kitchen fitted by a well known national kithen company in a B&B included Bosch CE marked washing machine and dishwasher with moulded 13A plugs rated at 2.9KW & 3.1 KW (at 220V), the manuals stated that removing the plugs invalidates the warranty.
The moulded plug on the DW was showing signs of overheating of the fuse or fuse contacts.

A DSO had been fitted to supply them on a spur from a DSO on a ring the other side of the celcon wall so the spur was only a foot long. The T&E had developed a fault in the wall due to heat. The heat damage was not at one end as would be the case with a loose termination.

As far as I was concerned the spur had been fitted in compliance with the regs. I will be only too happy to find out otherwise

Sadly not all trades work to the same regs as sparks and with the increasing grants available for insulation, heating upgrades etc I am finding that electrics are being compromised by these other works and one of the obvious points that crops up is the 'standard' 2.5mm spur of a ring being heavily insulated / boxed in with heating pipes / behind rediators....Of course I am sure that these are down to other trades and not installed like it by competant electricians