radial / ring

[mhar]

Simple job to add an extra socket to top floor 'rfc'. Top floor was converted some 8-10 years ago but no certs available. Took Zs from socket I was going to spur from which was .6ish Ohm, turned off supply, proved dead then took end to end readings (at socket I intended to spur from) to prove ring and all fine. Realised that ring cable (2.5mm) passed directly behind proposed new socket position so went down to cu to disconnect circuit before cutting cable to find that the mcb was feeding 1 x 6mm t & e. Spoke to owners who said that this cable had been upgraded during the conversion and feeds a jb at bottom of flight of stairs to top floor. They assure me this was done by an electrician.Whilst I haven't lifted carpets as they never go back the same, it does check out.
Therefore I have a ring beginning and ending at an 'accessible' jb which is fed from cu by 6mm t&e which does not comply with app 15 which is headed 'informative', so a radial ring combination. Making it a true ring as defined in App 15 is impractical due to floor tiles above lath and plaster ceiling. Load wise the ring could be broken and mcb downrated to 20A but this will actually increase the earth path resistance albeit still well within disconnection times. Mem board.
Arguments against leaving this as is please and how to describe circuit on cert

 

[Zebra Stripe]

Think they call this a lollipop circuit and was/is used sometimes. I'd leave it.

 

[telectrix]

as above. nowt wrong with leaving as it is. just add your new socket. if only 1 additional socket, can be a spur. take Zs from new socket. complete MWC. get paid. ( assuming you've checked earthging and bonding and rectified any defects).

 

[mhar]

Thank you both for the quick replies.
Bonding fine, incoming gas & water both in very close proximity to cu.
How would I describe the conductor csa's on mwc? The size of the cable leaving the cu which seems sensible to me or the csa's of the majority of the circuit? I will not be introducing any new cable, just cutting into existing 2.5. Obviously I will take advantage of the comments box to describe circuit.

 

[Eddiesparks]

I learned you always write down smallest cable csa that is on the PROTECTIVE DEVICE (which is why if you have an FCU on a ring feeding a(for eg) 1mm fused spur you dont put 1mm!!

Of course comments needed here!

 

[Octopus]

You find many lollipop circuits in kitchens where old cooker circuits have been adapted to utilise the "redundant" circuit.

Its a shame the so called "schemes" haven't issued any guidance on them!

 

[telectrix]

i'd put the smallest cable size of the circuit on the cert. or. if you can squezze it in the box... 6/2.5 with a note in comments.

 

[mhar]

Thank you all again.
So Eddiesparks are you saying that all my certs are wrong when I have put down 1mm as the csa for shower feeds when I have used 1mm from the isolator to connect to the fan?!!!
Before I get jumped on, I am referring to a recent thread

 

[Eddiesparks]

1mm is fine as long as the breaker is 50a. Thats what I heard from a bloke down the pub who said he knew loads about lectrics because he was a builder.

 

[telectrix]

1mm is fine as long as the breaker is 50a. Thats what I heard from a bloke down the pub who said he knew bugger-all about lectrics


corrected that for you.

 

[Deleted member 72666]

1mm is fine as long as the breaker is 50a. Thats what I heard from a bloke down the pub who said he knew loads about lectrics because he was a builder.

Nooooo! Don't ever take notice of builders regarding electrical work, it's painters you need to listen to!

 

[telectrix]

only on council jobs.

 

[mhar]

Now this is the type of stuff they don't teach you in college. Perhaps the 2330 should be a 4 year course.

 

[Guest55]

this type of circuit would be recorded and viewed upon as a radial , even though a ring exists within , due to only 1 conductor being terminated at the origin / opd.

and most cert boxes are just about big enough to write 6 / 2.5 in the conductor csa section , which is what i'd personally do.

 

[mickys86]

Nooooo! Don't ever take notice of builders regarding electrical work, it's painters you need to listen to!

Don't listen to them! If you can pi$$ you can paint!!