Ring main circuits appear to be radial at consumer unit.

[JohnW2]

Really 4mm radial? What would the average electrician install? I know the rational behind our UK ring circuits but I believed that was the required standard.

Not at all. Both radials and rings are acceptable, but radials seem to be becoming increasingly more popular.

Were it not for the dispensation (which involves a certain amount of guessing about how the circuit is likely to be used) the UK ring final circuit would not be compliant with the regulations. Such a circuit is not acceptable in many countries outside of the UK

So I can leave my other circuits which I believe are radial? That makes things a bit simpler.

As above, radial circuits are at least as acceptable as rings, provided the correct size cable is used in relation to the rating of the breaker protecting it. If 2.5mm² cable is used, the breaker would usually be 20A, perhaps 25A, but with 4mm² cable one can usually use a 32A one. The rating of the breaker obviously defines the theoretical maximum total load that should be supplied to the circuit.

 

[Jurassicspark]

Not doing a photo of that now. I’ve removed all of the wiring in the kitchen and will get a fresh ring installed. It seems to have been a radial with some sort of ring tied into it.

How did you get to that conclusion?

 

[sparkwright]

Not doing a photo of that now. I’ve removed all of the wiring in the kitchen and will get a fresh ring installed. It seems to have been a radial with some sort of ring tied into it. There’s definitely only a single cable going into all of the socket circuits. Three socket circuits and multi core cable going into them so I’m guessing they are 4mm2 radial circuits as opposed to my assumption that I had three ring circuits. What period do radial circuits come from? How is a householder supposed to know what he has got?

We didn't get the picture of the cu, so we didn't get confirmation of the size of the outgoing cables.
A 4mm2 cabke from the cu, going to a joint, which is connected to rwo 2.5mm2 cables in a ring , would have been perfectly acceptable.
Is that what you had?

 

[Murdochcat]

Is this a wind up? Posting the photo of the CU with the cover removed would have answered so many questions

 

[blup]

He's reinstating what he ripped out, satisfied that he's answered his own question.

 

[Murdochcat]

He's reinstating what he ripped out, satisfied that he's answered his own question.

Not sure i agree with this, very obvious the OP doesn’t want to show us his CU

 

[blup]

Not sure i agree with this, very obvious the OP doesn’t want to show us his CU

No he doesnt but that might down to over sensitivity on his part to the replies he got.

 

[Murdochcat]

No he doesnt but that might down to over sensitivity on his part to the replies he got.

A simple photo might just clear up any issues

 

[blup]

A simple photo might just clear up any issues

It would but he's picked up his ball and left the pitch.

 

[Murdochcat]

he was here just before 7 am today .........

 

[FrodoOne]

What period do radial circuits come from? How is a householder supposed to know what he has got?

Radial Circuits are almost universal - everywhere.
It is the Ring Circuits which are peculiar to the UK, ex British Colonies - and Saudi Arabia !
Elsewhere, they are (mostly) not allowed.

Really 4mm radial? What would the average electrician install? I know the rational behind our UK ring circuits but I believed that was the required standard. So I can leave my other circuits which I believe are radial? That makes things a bit simpler. As my feed to the kitchen is a 4mm I could just have it wired as a radial. In 4mm obviously.

To extend this story a bit further,
Australia based its Electrical Regulations largely on those of the UK.

Prior to "Metrication", (mid 1970s) Australian wiring supplying Power Socket-Outlets was the (approximate) equivalent of 2.5 mm².
At that time, with fuses in the CU, such circuits were Rated at 16 A.
With the introduction of Circuit-Breakers (with a faster response time) this Rating of 2.5 mm² cables was increased to 20 A,
when protected by Circuit Breakers.

Recently this has been changed.
Existing 2.5 mm² Radial circuit installations (protected by 20 A Circuit Breakers or RCBOs) may continue in operation.
However, if any "work" is done on any such 2.5 mm² circuit,
the MCB or RCBO must be changed to a 16 A rating.

Any New Work protected by 20 A MCBs or RCBOs must be in 4 mm² cable.

It seems that there are "regulation changes" abroad,
which may affect UK Regulations - sooner or later.

 

[ericmark]

Nothing wrong with a 4mm radial. Ideal for a kitchen.

2.5mm cable for ring could be cheaper

We should keep within volt drop, well published 106 meters considered limit with 2.5 mm² ring final. So your 4 mm² radial, using same formula, down to 25 amp as rating for cable only 27 amp, using installation method 100, and length restricted to 42.5 meters to be within volt drop, so half the cable, less load, and cable costs more, so why bother with radials.

We should plan each house, and for a ring final taking account of the total floor area being served. (Historically, a limit of 100 m² has been adopted.) but with a 4 mm² radial we are half of that, it is not the cable, it is the RCBO's which add the cost, also try getting 3 x 4 mm² into the socket terminals with 3 x 6 mm² even harder, to move from ring final to radials we would also need a change in back box and socket design to take the heavier cable, so in real terms not an option.

 

[EFLImpudence]

We should keep within volt drop, well published 106 meters considered limit with 2.5 mm² ring final. So your 4 mm² radial, using same formula, down to 25 amp as rating for cable only 27 amp, using installation method 100,

Don't use Method 100, then.

and length restricted to 42.5 meters to be within volt drop, so half the cable, less load, and cable costs more, so why bother with radials.

My kitchen is less than 40 metres from the CU; not to mention branches which add to the possible distance considerably.
Is the cost of the cable twice as much?

We should plan each house, and for a ring final taking account of the total floor area being served. (Historically, a limit of 100 m² has been adopted.)

Totally irrelevant.

but with a 4 mm² radial we are half of that,

Why?

it is not the cable, it is the RCBO's which add the cost,

Is it?

also try getting 3 x 4 mm² into the socket terminals

Simple.

with 3 x 6 mm² even harder,

Irrelevant.

to move from ring final to radials we would also need a change in back box and socket design to take the heavier cable, so in real terms not an option.

Not so.

 

[EFLImpudence]

Prior to "Metrication", (mid 1970s) Australian wiring supplying Power Socket-Outlets was the (approximate) equivalent of 2.5 mm².
At that time, with fuses in the CU, such circuits were Rated at 16 A.
With the introduction of Circuit-Breakers (with a faster response time) this Rating of 2.5 mm² cables was increased to 20 A,
when protected by Circuit Breakers.

Very sensible.

The UK ring circuit regulation is still written for BS3036 rewirable fuses.

 

[opps]

My kitchen is less than 40 metres from the CU

Blimey- how big is your home?