Rules and Guidelines
Want to participate in the discussions? Please read our Community Rules and Guidelines. Need some help? Visit Support and Answers.

  • Replies 15 replies
  • Subscribers 44 subscribers
  • Views 257 views
  • Users 0 members are here
Options
You may also be interested in

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?

Parents

  • Well, yes, you are right. I haven't fitted a RFC for over 10 years now. If you want 32amps, just fit 4 or 6mm cable to get that capacity. The cost between radial and RFC is minimal now, two radials will be slightly more expensive due to the extra RCBO required, but in the overall cost, it is tiny.

    Testing and fault finding are far easier with a radial. Downsides - in the event of someone not connecting the CPC correctly, and not testing it, some sockets/outlets may not have any CPC, which with a RFC would , probably still have a CPC connection. But , that is a testing problem, not the fault of being a radial circuit - and, as you have found, it is quite common to find RFCs without continuity on one leg.

    I think it's a laziness problem, in not understanding how the circuits work, and going for the easy option of fitting what they have always fitted. And as for needing the full 32 amps - whenever does that happen? Very rarely,if ever. My house is electric only. I've got no circuits above 20 amps, and have never had a tripped CB due to overload. Of course ovens/hobs are on a dedicated circuit (and I've lied then, my hob is on a 32A CB). General socket circuits are using les power now than in the last 50 years due to low power appliances in use now.

Reply

  • Well, yes, you are right. I haven't fitted a RFC for over 10 years now. If you want 32amps, just fit 4 or 6mm cable to get that capacity. The cost between radial and RFC is minimal now, two radials will be slightly more expensive due to the extra RCBO required, but in the overall cost, it is tiny.

    Testing and fault finding are far easier with a radial. Downsides - in the event of someone not connecting the CPC correctly, and not testing it, some sockets/outlets may not have any CPC, which with a RFC would , probably still have a CPC connection. But , that is a testing problem, not the fault of being a radial circuit - and, as you have found, it is quite common to find RFCs without continuity on one leg.

    I think it's a laziness problem, in not understanding how the circuits work, and going for the easy option of fitting what they have always fitted. And as for needing the full 32 amps - whenever does that happen? Very rarely,if ever. My house is electric only. I've got no circuits above 20 amps, and have never had a tripped CB due to overload. Of course ovens/hobs are on a dedicated circuit (and I've lied then, my hob is on a 32A CB). General socket circuits are using les power now than in the last 50 years due to low power appliances in use now.

Children
  • in reply to alanblaby

    Yes, testing is most definitely one of the biggest advantages of radials, and nowadays I'd say the cost differences are negligible. I'm in the same boat as you with running more dedicated circuits!

Community Rules & Guidelines