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Why are we still using ring final circuits?

David Berry

Hi all, I wanted to discuss the use of ring final circuits in electrical installations in the UK. 

I am an electrical contractor based in Surrey, England and, though I have predominantly spent my 20 year electrical career in the industrial sector, I have recently found myself in the domestic installation world - which has really opened my eyes to, what I believe to be, certain dangers of this installation practice here in the UK. I'd like to share two recent scenarios I have encountered domestically.

Scenario 1

I was called to a customers house to investigate a fault which was preventing the customer from switching on her 32A MCB without it immediately tripping. Upon beginning my investigation, I immediately discovered that the ring circuit in question had no continuity on both the Line and Neutral conductors. I also noticed that various sockets on the ring circuit had a black, sticky residue seeping from all 3 terminals of each outlet. After locating the fault causing operation of the MCB, I returned to the case of the broken ring continuity. I discovered that the Line and Neutral conductors had broken behind a countertop socket in the customers kitchen. It then became apparent that all sockets with the residue were sockets on the leg of the ring leading up to the broken point. Along this route were sockets feeding every appliance and piece of equipment in the kitchen, so my assumption is that the load, and subsequent heat, on this leg of the ring must have caused the insulation to deteriorate so and seep out from the terminals. 

Scenario 2

I was asked to install a few extra sockets onto an existing ring final circuit in a customers house to provide a newly built entertainment unit with several socket outlets. Immediately, I isolated the power and tested for ring continuity of the existing circuit only to discover, again, that the Line and Neutral conductors were not continuous. After a short investigation I discovered, much to my own and my customers horror, electrical cables protruding from a box with insulation stripped and copper conductors free to the touch. Whoever had removed an electrical accessory must have completely forgotten to return and re-connect it before turning the power back on. The scary thing about this one is that it was tucked away in a cupboard that my customers 8- and 10-year old sons kept their bike helmets - which the used every day to get to and from school. 

Both of these scenarios frighten me a little in the sense that these faults lay completely hidden and undetectable from untrained eyes. Because of the configuration of the wiring, nobody could tell that anything was wrong with the circuits, or that possible danger lay in wait. Does this not pose a huge, yet unnecessary, risk? To me there's absolutely no reason that we still need to be installing these circuits in 2026.

I personally feel that the industry as a whole might have gotten a little lazy. Showing up and installing numerous rings seems, to me, to be lazy design. Though I don't feel we're being taught any different. My apprentice informs me that they're still learning about them in college at the moment. Isn't it time we started designing our installations more efficiently: dedicated circuits for fridge/freezers, washing machines & tumble driers, induction hobs etc, 20A radials for ordinary sockets? Or, am I wrong? 

At the very least, 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. 

Does anyone agree?

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  • David Berry said:
    Whilst I duly note all the points regarding the use of the ring, I reiterate my point made above in my reply to aligarjon, 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. It's literally a free-for-all.

    I accept as a fact, that there are not strict controls on who can work on, alter and repair electrical installations ... however, banning ring final circuits in BS 7671 won't change that. It's a policy issue for the Government (MHCLG and the Building Safety Regulator).

    Your view appears to be based on the assumption that those who undertake deficient work on ring final circuits would actually conform to BS 7671 for other circuits ... in reality, if they don't take care (or know) how to complete and test a ring final circuit to ensure safety, they probably won't care (or know) about other provisions in BS 7671 in a similar vein.

    BS 7671 actually requires (Regulation 134.1.1) 'Good workmanship by one or more skilled or instructed persons and proper materials shall be used in the erection of the electrical installation.' So, clearly, failing to terminate and test a ring final circuit correctly does not conform to the standard already. Similarly, anyone working on an installation without the requisite knowledge and skills, where the work leads to dangerous conditions, is failing to conform to the standard.

    We are also having problems with professionals in the industry lacking the skills (or taking the care) to terminate SWA cables properly, or not using glands and other methods to meet external influences (causing inappropriate corrosion). This is leading some to recommend the armour is not used as a cpc ... yet BS 7671 requires the armour to be properly earthed because it is (or can become) effectively an exposed-conductive-part. It also requires external influences are taken into account during selection and erection. Should we ban SWA too?

Reply
  • David Berry said:
    Whilst I duly note all the points regarding the use of the ring, I reiterate my point made above in my reply to aligarjon, 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. It's literally a free-for-all.

    I accept as a fact, that there are not strict controls on who can work on, alter and repair electrical installations ... however, banning ring final circuits in BS 7671 won't change that. It's a policy issue for the Government (MHCLG and the Building Safety Regulator).

    Your view appears to be based on the assumption that those who undertake deficient work on ring final circuits would actually conform to BS 7671 for other circuits ... in reality, if they don't take care (or know) how to complete and test a ring final circuit to ensure safety, they probably won't care (or know) about other provisions in BS 7671 in a similar vein.

    BS 7671 actually requires (Regulation 134.1.1) 'Good workmanship by one or more skilled or instructed persons and proper materials shall be used in the erection of the electrical installation.' So, clearly, failing to terminate and test a ring final circuit correctly does not conform to the standard already. Similarly, anyone working on an installation without the requisite knowledge and skills, where the work leads to dangerous conditions, is failing to conform to the standard.

    We are also having problems with professionals in the industry lacking the skills (or taking the care) to terminate SWA cables properly, or not using glands and other methods to meet external influences (causing inappropriate corrosion). This is leading some to recommend the armour is not used as a cpc ... yet BS 7671 requires the armour to be properly earthed because it is (or can become) effectively an exposed-conductive-part. It also requires external influences are taken into account during selection and erection. Should we ban SWA too?

Children
  • in reply to gkenyon
    gkenyon said:

    I accept as a fact, that there are not strict controls on who can work on, alter and repair electrical installations ... however, banning ring final circuits in BS 7671 won't change that. It's a policy issue for the Government (MHCLG and the Building Safety Regulator).

    Your view appears to be based on the assumption that those who undertake deficient work on ring final circuits would actually conform to BS 7671 for other circuits ... in reality, if they don't take care (or know) how to complete and test a ring final circuit to ensure safety, they probably won't care (or know) about other provisions in BS 7671 in a similar vein.

    No, I simply feel that because we have no control over who is carrying out work domestically, it might safeguard it slightly better to use radial circuits on the premise that should mistakes be made and conductors lost, it might become more apparent to the user sooner, rather than later, as downstream points will cease to work. If, for instance, they make errors on lighting circuits then it is immediately apparent because they will quickly notice that some of the lights are not coming on. But when errors of this kind are made on ring circuits, those who don't care to test a ring circuit after altering it, or the customer, are none-the-wiser because it is being fed from two directions, and now a latent fault lies within the circuit.

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