Why are we still using ring final circuits?

I'm in the same boat as you with running more dedicated circuits!

Before you go too far down that route - have a look at what the French need for a domestic DB (tableau electrique) - never mind one or two rows, it's usually 3 or even 4.

had a black, sticky residue seeping from all 3 terminals of each outlet.

Does sound more like a variation of the "green goo" problem (a result of dodgy PVC recipe and time) - overheating PVC insulation more usually produces dry deformation, discolouration and charring. I've seen several instances of entire kitchens being fed from a single 2.5mm² T&E - without the slightest sign of distress.

if this kind of fault occurs on a radial circuit then some points - at the very least one - will cease to work and give the user of the system an indication that something is wrong. 

Swings and roundabouts - a c.p.c. break in a radial can go unnoticed too leaving everything apparently working but hazardous - whereas in a ring its likely everything remains earthed, significantly mitigating the risk.

I don't believe that we currently have controls over who can freely alter and work on electrical installations in domestic premises here in the UK.

There are some controls - via Part P of the building regulations in England/Wales for instance. Minor works are exempted from notification though. Overall there seems to be little evidence that strict licensing makes any significant improvement though. Those that don't care will carry on as before and ignore the new rules just as they ignored the old ones. Some of those with the appropriate badge will not always do a proper job. My own experience with "closed shop" trades almost ended tragically - a fully qualified Corgi (as it was then) gas fitter (from a well known national company) had left the fireplace closure plate around my parent's gas fire so badly fitted that most of the flue gasses were floating into the room rather than up the chimney - if my Mum hadn't mentioned feeling unusually sleepy in the front room when the gas fire was on, leading me to have a closer look, it could have easily have been lethal. There is a lot to be said for someone doing the work to have a vested interest in the safety of their own family. Education is the key, I think.  On a wider scale, the classic example was Australia and New Zealand - which had practically identical wiring codes, and practically identical electrical accident rates - despite Australia having a very strict licensed electrician system and New Zealand having almost a DIY free for all. 

but I feel that more should be done to encourage radial circuit use with dedicated circuits for different electrical items. The fridge/freezer is the best example I can think of - who wants their fridge/freezer to be knocked off due to a fault somewhere else on the circuit

That's a more interesting one. Partly the problem as arisen from the "fashion" for MCBs and RCDs in the CU. With the original ring circuit design - 13A fuse in the plug, 30A fuse for the circuit and 60A cut-out fuse there was pretty much total discrimination - so a fault in any appliance (or lead after the plug) disconnected just that appliance and left the rest of the circuit functional. We could have gone down the route of putting RCDs at the socket (as is much more common in the US with their GFCI receptacles), or even in plugs, but alas, up-front cost considerations prevailed.

   - Andy.

AJJewsbury said:

I'm in the same boat as you with running more dedicated circuits!

Before you go too far down that route - have a look at what the French need for a domestic DB (tableau electrique) - never mind one or two rows, it's usually 3 or even 4.

Andy, yes, I don't feel we would ever require going down the route of having that many - I couldn't imagine why that would be required, though interesting to knnow.

AJJewsbury said:

had a black, sticky residue seeping from all 3 terminals of each outlet.

Does sound more like a variation of the "green goo" problem (a result of dodgy PVC recipe and time) - overheating PVC insulation more usually produces dry deformation, discolouration and charring. I've seen several instances of entire kitchens being fed from a single 2.5mm² T&E - without the slightest sign of distress.

Thank you for this knowledge - maybe this was the case I encountered.

AJJewsbury said:

Swings and roundabouts - a c.p.c. break in a radial can go unnoticed too leaving everything apparently working but hazardous - whereas in a ring its likely everything remains earthed, significantly mitigating the risk.

I don't believe that we currently have controls over who can freely alter and work on electrical installations in domestic premises here in the UK.

Yes, I had thought of this which is why I now incorporate a high integrity version of earthing in my circuits now. I still essentially run a ring circuit so that the earth is connected in a ring. I then leave the connecting line and neutral cables between the furthest two points disconnected, leaving two radials. It dawned on me recently that i could do this also by running a 3C & earth cable as a radial, utilizing the black as an earth too. 

AJJewsbury said:

My own experience with "closed shop" trades almost ended tragically -

I had been wondering whether there is a similar problem in the gas trade. AFAIK, getting to be registered as a gas fitter is more onerous than an electrician. Moreover, Any tradesman who does gas work must be Gas Safe registered i.a.w. R.3 of The Gas Safety (Installation and Use) Regulations 1998.

That said, I am not sure that an owner occupier is forbidden to do any gas work at all. R.3 again: 3.—(1) No person shall carry out any work in relation to a gas fitting or gas storage vessel unless he is competent to do so. I reckon that I am competent to change the thermocouple on my boiler, because I can remove and replace the pilot light safely. I would not want to do more.

Back to the gas fire - Part J of the Building Regulations requires a CO alarm to be fitted to each room which contains a combustion appliance.

David Berry said:

utilizing the black as an earth too

Would that comply with 514.4.2?

In what sense?

In what sense?

In the sense that it is not green and yellow.

Well. of course - it would obviously be identified as an earth conductor using green and yellow sleeving throughout it's length.

It's OK to oversleeve another colour with G/Y at terminations (commonly done with 3-core SWA after all) - it's just a G/Y can't be oversleeved with anything else.

   - Andy.

I think that 514.4.2 clearly reserves the use of G/Y for a protective conductor and no amount of oversleeving changes that.

The word, "exclusively" troubles me a bit, inasmuch as it is not unambiguous.

Hopefully, GK will be along soon.

Chris, I feel you may be misinterpreting that regulation, or misunderstanding what I was intending. We are allowed to use the black, and sleeve it with green & yellow.

I used some 4mm 3 core SWA this week. The colours were brown/blue and green and yellow.  First time I have seen it.

Gary

aligarjon said:

I used some 4mm 3 core SWA this week. The colours were brown/blue and green and yellow.  

BS 5467 recommends 3-core SWA to be identified either by alphanumeric, or brown-black-grey. It's certainly limiting to the use of the cable given Regulation 514.4.2 does not permit oversleeving of a green-and-yellow conductor (unless it's a PEN conductor).

Also, including a cpc in the cable does NOT take away from the fact the armour is still (most often) an exposed-condductive-part, and:

• faults from a live conductor to armour can still occur
• the armour must still be rated as a cpc for the prospective fault current and adiabatic, although if the cpc is continuous at both ends, and we ignore the fact that the internal cpc could be severed as part of the 'fault' under some circumstances, some designers are happy the 'parallel cpc' can 'reinforce' the armour and help distribute the fault current (industry guidance has calculations for this purpose).

aligarjon said:

I used some 4mm 3 core SWA this week. The colours were brown/blue and green and yellow.

Yup - a favourite of mine - often found in wholesalers that also serve the Irish Republic (as they seem not to like relying on the armour as c.p.c.) and also in some DIY sheds. Most UK wholesalers seem to prefer to stock only the Brown/Black/Grey variant ... which I suppose has the advantage that you can oversleeve one of the cores as G/Y but you can't oversleeve G/Y for use as a live conductor.

  - Andy.

Ive used that stuff with the single phase colours too, in some ways its more satisfying, from memory a little dearer than the 3 phases no neutral  coloured stuff.
Its a bit like twin and earth with the full size and already insulated CPC, also rare, but once tried, you end up wondering why we like grovelling about for bits of sleeving that drop to the floor, but only when you are right at the top of your wobbliest steps and it's getting dark...
M.

AJJewsbury said:

(as they seem not to like relying on the armour as c.p.c.)

It's this bit I don't get 100 %, because the armour MUST be properly earthed as it's an exposed-conductive-part, it's usually of suitable size, and if it needs 'reinforcing' as a cpc, then there must be good connection at both ends?