EICR code for ring within a ring

when you say ring within a ring, I may not have the right picture -

do you mean figure of 8  with  4 wires meeting at some point to make a waist ?

Or a sort of circle with a double track section almost as if we had 2 spurs from different parts of the ring  that joined up ?

Are there

just 2 ends at the CU not 4 ?

All sockets 'mid ring' not spurs ?

But ring-round resistance different from different sockets ?

Either would be unusual, and quite likely a  mistake. Certainly not in the OSG or other lists of pre-packaged circuits that require no design effort, but  neither is very likely to be dangerous at 32A if all cable is 2.5mm, all sockets are fed from two cables,  and these are well made off.

Problem is how to be sure ? 

As you say a 20A MCB is one dead cert way not to overload a cable, and a common fixall for the ring that has been crab clawed into a centre fed radial, but you probably do not need to. Is the cable showing signs of distress anywhere ?  If not could well be c3 with the breaker left alone.

Also, if badger has been at it how confident are you it is indeed the right sort of cable and there are no funny joints anywhere hidden.

Mike.

'badger'  being a reference to being  rough as a... not entirely PC link.. 

If you just mean two rings connected as one circuit at the fuseway then no problem it`s just one ring final circuit (providing all other considerations for overloading , volt drop, disconnection times etc etc are met)

At the moment I am just going from test results and haven't actually found where the two rings may be joining and now beginning to be a little bit unsure about my initial conclusions.

I didn't have much time to actually investigate further yesterday, I know that if there are two rings they don't join at the consumer unit. The Kitchen and conservatory are of a newer build, therefore if it is a figure of 8 it would have happened when these were connected in to the existing wiring.

The kitchen and conservatory are giving me an R1+R2 0f 0.17 with about 20 points

Then other parts of the house gave 0.54

I think that I had comparable results for R1+Rn but didn't make notes so can't be sure, therefore earth bonding in the kitchen could be making the difference. Still trying to think this through but my gut feeling is that if it was earth bonding I would see gradual changes around the circuit rather than two distinct groups of results for two areas.

I haven't found the joining point and it's quite likely that I haven't looked behind sockets on the shortest route from there to the consumer unit as I only looked behind 8 out of 30+ points on the circuit. Therefore don't know if there are any thermal issues, but the cables in the consumer unit looked ok.

loads on the circuit

2 ring induction hob, Dish washer, washing machine, kettle, iron, 2 portable dehumidifiers, old chest freezer, full height fridge, extractor fan, 2 TV's, various lights, phone chargers etc. Any tools that may be used in the garage or other utensils in the large kitchen. Making some guestimates on the numbers I am wondering if I could get away with a 20A breaker as most of the loads are intermittent and they would all need to be on together for quite a while before it actually trips.

Hi Alan,

if I got this right from what you`ve said then it`s not just a two ring circuit with both rings on the same fuseway therefore 4 conductors at L & N & E (excluding any spurs you might or might not have) but the commoning somewhere else.

If, example, we consider a clockwise ring of 20 sockets and the second ring of say 10 sockets might be jointed onto say socket 1 and socket 20 respectively or some such similar set up.

I suspect you`ve taken readings not at the consumer unit but from a point somewhere on each ring for your continuity checks for two apparent separate rings.

It certainly is interesting to try and approximate which way the current might load the various legs with this setup.

If instead of joints being at the socket connections themselves but at ( hidden) junctions around the big ring then it makes it all the more difficult too.

With the set up you seem to have and the likely loadings I don`t think it at all likely that loading issues will actually be a problem but if you get heavier loads, say an extra dryer, washer, dishwasher and oven then yes it does start to make tracing what you have more important. 

Tracing out might be very time consuming. If you succeed it would be nice to know what you`ve concluded it is and the best way to improve it.

I think that I'd want to plot the test results on a plan of the house, and unless I have missed it, you haven't told us where the CU is in relation to the 2 "rings".

With only 2 (T&E) cables in the CU, it appears that the larger ring is arising from the smaller one. So if for the sake of argument it has 6 points, the larger/outer ring comes off at point 3 and rejoins at point 4, or as ebee has pointed out, it could be at a JB between points 2 and 3; and 4 and 5, for example.

Another way of looking at it is one long ring with a short circuit (or waist) between two points - they don't all have to join in one place.

Good luck!