CU change - ring on end of radial

[ProDave]

I did the inspection yesterday prior to a CU change (and some other minor works)

The only thing "wrong" is the kitchen which is a later addition single storey extension leaves the CU as a 6mm t&e but in the kitchen it's wired as a ring in 2.5 t&e

I've checked every socket in the kitchen by measurement at each socket to confirm it really is a ring in the kitchen not a 2.5 radial.

So it looks like someone has taken a 6mm from the CU to a junction box somewhere, from there it runs as a ring around the kitchen.

Is it okay to proceed with the CU change and just note this as a departure. While it's certainly unconventional, apart from not yet identifying and checking the junction box, I can't actually see anything unsafe about this.

 

[Doc Hudson]

Not the best, but if you say it is electrically safe, the only issue I see is can see is access to the joint on the 6.0mm?

Doc H.

 

[Apache]

It's not on the cooker circuit? How about an old electric shower that was removed and cable re-used?

 

[ProDave]

It's not on the cooker circuit? How about an old electric shower that was removed and cable re-used?

The cooker is on it's own circuit.

A disused shower circuit is quite likely. There is no electric shower in this house (thought they want me to fit one in the utility room, but that's another topic for later). It's a big rambling house and running a new ring from front to back would have involved a lot of floor boards up, so if a redundant shower circuit was available they might have used that. That also gives me a clue where to look for the mystery JB, somewhere near the bathroom.

 

[Lurch]

I've done it a few times on kitchen refurbs or where a ring is a reasonable distance from the board. I realise it's unconventional but I couldn;t find anything to prohibit specifically.

 

[ianmacd]

Its actually a radial since it doesn't comply with the definition of Ring Final Circuit in Ch2 and also doesn't comply with 543.2.9 or 433.1.5.

What overcurrent protective device is used for this radial?

 

[ProDave]

Its actually a radial since it doesn't comply with the definition of Ring Final Circuit in Ch2 and also doesn't comply with 543.2.9 or 433.1.5.What overcurrent protective device is used for this radial?

At the moment it's a rewireable wylex 30A fuse.

But I've been doing some minor alterations and checks on this property in preparation for a CU change, so it will be a dual RCD split board and 32A MCB.

Apart from being an unconventional circuit arrangement, I can't see anything stopping the CU change going ahead, on the basis it will be "no less safe" than before, and in view of RCD and MCB in place of rewirabale fuse, it's arguably a lot more safe.

 

[NozSpark]

Whilst this might look unconventional I can't see an problem with it, so long as the calcs and testing work out ok...

Maybe we should call these "lollipop" circuits??

 

[m4tty]

Radials rings n lollipops lol

 

[Apache]

Whilst this might look unconventional I can't see an problem with it, so long as the calcs and testing work out ok...Maybe we should call these "lollipop" circuits??

That has been suggested before, but can't seem to find it. I can vividly see KME saying that they happen commonly on an industrial scale, just not in domestics and that nothing fundamentally wrong with them.

Grr - will look harder tomorrow.

 

[initforthemoney]

Sounds to me like there could be a few regs not being complied with.

 

[Lurch]

Sounds to me like there could be a few regs not being complied with.

Really? What would they be then?

 

[Andy™]

Sounds to me like there could be a few regs not being complied with.

like?

look at it this way. if you add a small enclosure at the point the ring starts, and add a 32A MCB, then it will be a subamin radial, and final circuit. so, electrically, whats the difference?

 

[initforthemoney]

[quote name='Andy

 

[Lurch]

I agree in that respect, however the OP does not have this set up.It has a hidden JB that the RFC starts from, which is does not conform.

Who said it is hidden? It is as yet unlocated, not necessarily hidden.

 

[Andy™]

I agree in that respect, however the OP does not have this set up.It has a hidden JB that the RFC starts from, which is does not conform.

How is testing carried out satisfactorily?

Page 362.

who says it needs to be accessible? it may well be crimped or soldered connections

 

[PC Electrics]

Whilst this might look unconventional I can't see an problem with it, so long as the calcs and testing work out ok...

Spot on. When changing the CU your responsibility for the existing circuits extends only as far as proving that they are adequate and safe to be reconnected to the new CU. As long as your IRs & continuities are okay then in this case the circuit is adequate to be connected to a new 32A way.

You're not there to disect the installation in every minute detail and condemn it based on every little discrepancy that can be found, otherwise we'd have to change every piece of green earth sleeving in every 60's house to green/yellow or chop out and reroute every diagonal cable we ever found!!

Whether the "joint" is accessible or not isn't material unless you suspect it is faulty and affecting the adequacy.

Make a note of your findings in the 'comments' box.

Also, as pointed out somewhere above, you will have left the instalation "no less safe" than it was before. In fact, considerably safer with RCDs installed.

 

[ProDave]

Who said it is hidden? It is as yet unlocated, not necessarily hidden.

Precisely. I know there must be a JB somewhere, I just don't know where yet.

I have other work at this property prior to the CU change, and when i'm next there I will have a look for this "hidden" jb, starting near the bathroom on the hunch as suggested above it might be a redundant shower circuit that's been used to feed the kitchen ring.

 

[Badger]

id be looking in or around the airing cupboard area, to start with as usually the shower cable goes up through airing cupboards in most circumstances ; )

 

[initforthemoney]

[quote name='Andy