Ring final & Radial circuits off one mcb ?

[Octopus]

How you actually word the multiple circuits, or cables at one device on the Report recommendations.

I would show 2 lines on the schedule of results for clarity.... And a note that they are both terminated at the same mcb

 

[westward10]

À note to separate them as a C3?

 

[Pat H]

Isn't it failing to provide diversity in case of failure? A RFC with as many outlets can only be on one MCB and if it trips they are all dead. But if you have 2 "feeds" to 2 sets of outlets at the CU then joining them into one MCB if failing to provide diversity between them.

 

[westward10]

How is that poor diversity.

 

[Pat H]

How is that poor diversity.

Well its not diverse at all. Its one circuit but could easily be 2 circuits. 2 circuits would offer diversity. 1 circuit doesn't.

 

[westward10]

Think you mean division of circuits.

 

[Risteard]

2 circuits would offer diversity (sic). 1 circuit doesn't.

That argument would only stand up if you were to claim that every socket outlet and luminaire should be on its own circuit. Otherwise you are accepting the fact that multiple accessories can be on one final circuit in spite of the potential inconvenience this might cause.

Also, what level of inconvenience will arise from a power cut? Does this really present much danger?

 

[Flanders]

Kind of agree that it is one circuit but would test it as two circuits and note both on the report after all you have 2 end point which will have 2 sets of reading , I supposed you could record just the highest reading , but has I have done all the test I like to write them down , I had some the other day with 2 ring finals in 1 MCB (4 cables) or is that a figure of 8 ring final ??? as it happens one of the rings was not continues due to alterations so a right old mess , Back to the OP it sound like its just ruff but not dangerous, unless the cables are not terminated very well due them being different sizes in the same terminal as others have suggested,
PS How do you agree/like a post ???

 

[Risteard]

What exactly do you dislike about my post (#27) westward10?

 

[westward10]

Sorry Risteard didn't even realise I had done that, gone now

 

[Risteard]

Sorry Risteard didn't even realise I had done that, gone now

LOL. Fair enough. I wasn't sure what I'd said to upset you!

 

[Des 56]

 

[Wilko]

... Next ring final on a 30A feeding upstairs sockets as usual but on cover removal I found a 4mm t&e spurred from same 30A mcb and feeding opposite side of garage to sockets all on the 4mm then at the end spurred from last socket with 2.5mm t&e to feed new water cylinder via a DP switch ...

Hi - my post beverage take on this - BYB App 15 gives guidance on how rfc and radial ccts are to be arranged. They are separately shown and I take that to mean they should not be mixed. So I think the arrangement Soulsurfer found is not in accord with BYB. If I was to connect an rfc and radial to the same mcb and present it to a QA I would expect earache

 

[Risteard]

Hi - my post beverage take on this - BYB App 15 gives guidance

Exactly - it is guidance. Appendix 15 is informative, not normative, and therefore does NOT form part of the Wiring Regulations.

 

[Wilko]

Exactly - it is guidance. Appendix 15 is informative, not normative, and therefore does NOT form part of the Wiring Regulations.

Got that, thanks.
But I'm not clear - are you saying I've interpreted the information incorrectly ?

 

[Marvo]

Well its not diverse at all. Its one circuit but could easily be 2 circuits. 2 circuits would offer diversity. 1 circuit doesn't.

It's better to avoid the term diversity unless your applying it as the true electrical definition.

It's probably poor circuit design that could provide inconvenience for the installation user.

I'd also agree with Dave that a ring and a radial final (and any other installation arrangement) from the same OCPD should be considered as being a single circuit for technical purposes.

 

[Soulsurfer]

Rough as it definitely is, there are at least 2 ways spare in the existing cu where ocpd's could have & should have been fitted and avoided this ! Thanks to all for your opinions though as whichever way individuals interpret the BYB it is certainly not something I'd want to show my assessor as my work on a visit !

 

[davesparks]

Though the interpretation is such, I think its a bit daft. I've often come across one mcb protecting a number of "different" circuits. Tested them and recorded them as individual which to me makes sense (I could be completely wrong of course), even though I'm well within the regs to just record the highest readings of which ever "circuit" produces them.

If necessary you can record the two parts of the circuit on separate lines of the schedule of test results but identify them as being the same circuit.
I do similar to record all the necessary information for a lollipop circuit

 

[davesparks]

Hi - my post beverage take on this - BYB App 15 gives guidance on how rfc and radial ccts are to be arranged. T

They are just the standard circuit layouts which are a quick and easy circuit which can fulfill the basic requirement of installing general use sockets.
They are not a guide to the only way or preferred way to install a circuit, a competent person can design a compliant circuit in any way they wish.

 

[westward10]

Debatable whether someone who whacks another circuit onto an existing one is competent, different standards eh.