Consumer unit query

[Harry Bloomfield]

Isn't it possible that the leg going under the floor is one of the ring final legs, and one of the others that goes up is the other, then the remaining two are spurs or another ring final.

Simple test, is power off, disconnect, and untwist the ends - then check for continuity between every wire and every other wire. That you provide clues of which wires are part of a ring, and which ring.

Twisted 2.5mm, suggest a quite amateur DIY job.

 

[JohnW2]

Twisted 2.5mm, suggest a quite amateur DIY job.

Maybe, but I have to say that I was 'taught' (told) to do that by a very experienced and respected 'old-school'('time-served') electrician. In his defence, I presume that he must have been brought up in the days of stranded conductors, which may be part of the explanation.

Kind Regards, John

 

[securespark]

Was going to say, all the time served guys when I started did the same.

 

[jurassic sparkk]

Isn't it possible that the leg going under the floor is one of the ring final legs, and one of the others that goes up is the other, then the remaining two are spurs or another ring final.

but what about the kitchen its concrete and i dont see no wires going there

 

[Harry Bloomfield]

but what about the kitchen its concrete and i dont see no wires going there

Post #31, is the only way to disentangle it.

 

[jurassic sparkk]

314-01-04 Where an installation comprises more than one final circuit, each final circuit shall be connected to a
separate way in a distribution board. The wiring of each final circuit shall he electrically separate from that at every
other final circuit, so as to prevent the indirect energising of a final circuit intended to be isolated
Must have been diy dave

 

[Murdochcat]

314-01-04 Where an installation comprises more than one final circuit, each final circuit shall be connected to a
separate way in a distribution board. The wiring of each final circuit shall he electrically separate from that at every
other final circuit, so as to prevent the indirect energising of a final circuit intended to be isolated
Must have been diy dave

Wrong. 4 cables could be a single circuit

 

[EFLImpudence]

The Wiring Regulations definition of circuit:

"Circuit. An assembly of electrical equipment supplied from the same origin and protected against overcurrent by
the same protective device(s)."

 

[EFLImpudence]

That is a bit contradictory, isn't it?

314-01-04 Where an installation comprises more than one final circuit, each final circuit shall be connected to a
separate way in a distribution board.

Not possible to do otherwise.

 

[Taylortwocities]

That is a bit contradictory, isn't it?


Not possible to do otherwise.

Yes it is.
I have been to several installations where DIYdave (and electricians) have mixed up the legs of two ring final circuits. this means that one leg of Circuit A goes to MCB1 and the other leg to MCB2. and one leg of Circuit B goes to MCB1 and the other leg to MCB2.
The give away for this mistake is that to isolate a circuit one has to turn off both MCB1 and MCB2 to isolate either of the circuits.

Obviously a lack of even basic testing after having done some work. Turn it on, everything works, so it must be OK.....

 

[Murdochcat]

Unless somebody competent with proper test kit actually does some proper tests, nobody can really advise ….

 

[JohnW2]

314-01-04 .....

How old is that ??

Where an installation comprises more than one final circuit, each final circuit shall be connected to a
separate way in a distribution board.

As has been said, for as long as I can remember, the Wiring Regs/BS7671 has defined 'a circuit' (which, in practice, means 'a final circuit) as being everything protected by the same OPD. So, at least for the last decade or three, it has been impossible for more than one final circuit to share one OPD, since, by definition, everything protected by one OPD is one final circuit.

Kind Regards, John

 

[JohnW2]

I have been to several installations where DIYdave (and electricians) have mixed up the legs of two ring final circuits. this means that one leg of Circuit A goes to MCB1 and the other leg to MCB2. and one leg of Circuit B goes to MCB1 and the other leg to MCB2.

I did it once .... but ...

Obviously a lack of even basic testing after having done some work. Turn it on, everything works, so it must be OK.....

... I detected and rectified the error (by testing) before anything was energised

Kind Regards, John

 

[EFLImpudence]

How old is that ??

I didn't notice that - 314-01-04

It was still 314.4 in the last book.

 

[securespark]

How old is that ??

I have not yet found any reference to the contents of that reg any earlier than the 15th Edition, 1981.

In that book, it was labelled as regulation 314-4.

In the 16th Edition, 1991, it was 314-01-04.

In the 17th Edition, it was 314.4. Is it the same in the 18th Edition?