What Reg states you cant have 2 RFC's in one fuse?

[lawrence0117]

Hey guys, just out of interest, just completed a job for a customer but whilst i was in the board(old 5 way wylex) i noticed both ring circuits on one 32a fuse (space saving?)and cant rememeber off the top of my head and wondered if one of you lovely people knew the actual reg that states its a possible no no? i know its bad practise but just wondered if there was an actual reg?
Cheers,
lawman

 

[SPARTYKUS]

can't think of a reg apart from the one about separation of circuits and discrimination betwixt them (sorry no regs to hand)

As a safety thing can't think of a bad point apart from premature ..... tripping. As in too many things plugged in expecting the capacity afforded by two RFC's

 

[Sparky Ninja]

If they are both installed separately in accordance with appendix 15 and 433.1.5 then the only issue is with regard to section 314 (Division of installation).
I suspect though that it is likely that 433.1 will not be complied with as it is likely that "Ib" will possibly exceed "In" in some circumstances.

 

[lawrence0117]

Ive been looking through regs and scratching my head! Thats what i thought, from a safety point of view the only bad point might be its gonna trip because they may overload it in the future? well, i pointed it out to them but they said they havent ever had any trouble so mehh!!

I like what your saying widdler 314 looks good, just found it in regs and 433.1!

cheers for your quick knowledge!

 

[GaryM]

Definition of a 'circuit' - An assembly of electrical equipment supplied from the same origin and protected against overcurrent by the same protective device(s).

Two ring finals in one MCB would be one circuit, not two circuits in one MCB. Pretty crap though.

 

[Deleted member 26818]

Yes I was going to say something similar.
There's no Regulation about it, as it's an impossible situation.

 

[Paul.M]

Definitions, rfc = a final circuit arranged in the form of a ring and connected to a single point of supply.

No mention of 2 rfc on the same point of supply. Erm good question.

Only other thing from top of my head is appendix 15, "An unfused spur may be connected to the origin of the circuit in the distribution board". It says "an" not "another ring".

 

[Paul.M]

Have a look at the first line of reg 537.2.1.1 and now member the description in definitions of a "ring final 'circuit'.

Imho a rfc is one circuit and two should not be placed on the same mcb/fuse.

 

[GaryM]

In that case, two times two loops of cable connected together in a single MCB isn't a ring final circuit, merely two times two loops of cable in a single MCB and by definition, a circuit.

I'm not arguing a case for this cack design of a circuit, just struggling to argue against it.

 

[Paul.M]

Doh, I've written a long post and lost it in cyber space. Not doing it again, its to late.

Gary I agree with you. In the end there is no reg set in stone against this but would anyone of us do it? No.

Can anybody show us a reg?