Domestic Ring Main

Discussion in 'Electricians' Talk' started by spike47, Jul 20, 2022.

  1. spike47

    spike47 Member

    Hi
    Checked out a friends CU to isolate lower ring main, just to change out a dud double socket, they have just had stairs a bedroom and bathroom fitted in there bungalow, but it seemed strange to me that there was only one 32A ring main mcb in the CU, did not remove cover of CU to see if 4 wires went into the 32A mcb, but should the upper and lower be wired as separate ring mains, just didn't look right to me, maybe I am missing somthing here !.

    Spike
     
  2. Rulland

    Rulland Screwfix Select

    If it's a bungalow there's probably just one ring final, and they've just extended it into the new upstairs rooms, common practice in my experience Spike, easier than running in a new circuit.
     
  3. Ind spark

    Ind spark Screwfix Select

    Or the new floor could be on a radial.
     
    spike47 likes this.
  4. spike47

    spike47 Member

    Hi
    Thanks for your reply, how would they do that ?, the lower ring main final is under the groundfloor floor boards , so they would have to bring the upper cabling down to the CU in any case, Ive got a feeling they have have just gone into the 32A MCB already being used for the lower Ring main !.
    Spike
     
  5. spike47

    spike47 Member

    Only one 32A MCB in the CU apart from 2 x 6A ! .

    Spike
     
  6. The Happy Builder

    The Happy Builder Screwfix Select

    Installing a completely new socket ring circuit for one bedroom would be completely over the top.

    A new 16 amp radial socket circuit or simply extending the existing socket ring circuit is more than ample.
     
    spike47 likes this.
  7. chesterw

    chesterw Well-Known Member

    If it ain't broke don't fix it.
     
    spike47 likes this.
  8. The Happy Builder

    The Happy Builder Screwfix Select

    I have seen electricians replace a 3-way fuse board in a bungalow lights, sockets and cooker with a Dual RCD 16-way consumer unit.

    If we have to start fitting Arc Fault Detection Devices they will soon stop doing that!
     
  9. Bazza

    Bazza Screwfix Select

    One ring final for a house was not at all unusual a few years ago. Nothing to concern yourself about.

    But, the additional electrical work that was done for the extra room must have been accompanied by an installation certificate. What does that say?
     
    spike47 likes this.
  10. spike47

    spike47 Member

    Hi
    Asked her, she dosen't know what I was talking about, prob is somewhere !.
    Spike
     
  11. spike47

    spike47 Member

    Hi
    Thanks for your reply, I understand what you are saying, but if they have to bring the upper cabling down to the CU, why could they not just put in another mcb for that circuit, then if it trips they will still have the lower ring main or vice versa !.
     
  12. Bazza

    Bazza Screwfix Select

    Err probably because they are builders and not registered electricians.
    “another MCB” means it would then be a new circuit, and that would be notifiable electrical work.
     
    spike47 likes this.
  13. spike47

    spike47 Member

    Thanks Guys for all your feed back, am going to look in that CU next time I am around there !.
    cheers
    Spike
     
  14. MGW

    MGW Screwfix Select

    In the 1980's it was still common to fit a Wylex fuse box with 4 fuses, 30 amp for ring final, 30 amp for cooker, 15 amp for immersion and 5 amp for lights. The whole supply came from a 60 amp DNO fuse.

    Splitting this supply caused many problems, I have seen the results, two 20 amp supplies to sockets, but no one clearly tested first before splitting the ring final, and one leg the volt drop well over the then 4% allowed (now 5%), and with the lights often you would find a borrowed neutral where the lights were split upper and lower, and there was two way lighting on the stairs.

    The problem was until some one came to swap a fuse box to a RCD protected consumer unit, these faults were unknown, when I did my apprenticeship in the 70's, the loop impedance meter was kept in the foreman's office, and was never used, just an ornament on the shelf, together with the regulations book, asking to use or view them, was met with why do you want to?

    It was only when BS 7671 came out, and the 16th Edition exam, that run of the mill electricians actually got their hands on the book, so 1992 was when domestic electricians started to actually follow regulations, and it was not until Part P in 2005 that they were forced to get certificates to say they could read the book.

    House electricians were refereed to as house bashers, and were considered as just above the electricians mate, in fact often the electricians mate wired the house, and an electrician would pop in to see all ways OK. The Emma Shaw case stopped this, but this was not until 2014. The hardest system a domestic worked on was the central heating.

    Things have clearly changed now, with solar panels, EV charging, and other innovations, and today few electricians can freely swap between domestic, commercial, and industrial, each has become more specialised, be it dressing cables with installation being careful not to mark the gland, or programming PLC's, the trade has split into specialist sections.

    But with domestic so much has changed, industrial common for one guy to design, second to install and a third guy did the inspection and testing, I have fitted cables with no idea what they supplied, but domestic common same guy does start to finish, and he needs to work out volt drop, earth loop impedance, fire stopping, and requirements when penetrating fire barriers, the lot, as industrial I may have helped the safety officer walking around with a smoke generator testing the smoke alarms, but it was not my job to decide where the smoke detectors should be located, or break glasses, little more involved with petrol-chemical, but when working with Hawk glands I was given special training first. The industrial electrician had so many tool box talks, keeping us to to date, main thing was we often worked as teams, in all my time I have never made off a mineral insulated cable gland, there was always some one in the team who had done one before. But with the sole trader domestic electrician he has to know the lot.

    I remember around the turn of the century, thinking I am entering the ELI ect. on forms, maybe I should work out what they mean? and what is the pass mark, we would write down EEBADS or something like that, without really knowing it stood for "Earthed Equipotential Bonding and Automatic Disconnection of Supply" it was just something put down on every form. So I returned to collage and University and realised I likely made loads of errors in the last century.

    But back then there was no scheme provider inspector coming and checking my work, or LABC inspector, and I know I did make errors, like fitting earth cables to static caravans unaware of how an ELCB-v worked, and I was effectively shorting out the safety device. Not seen one in years, they were banded, and the ELCB-c/RCCB/RCD or RCBO has replaced them. However one may still come across one, and this is where the collage education kicks in, when you come across some thing from a by-gone era. Maybe I am just getting too old, I still remember dash pots and knife switches.
     

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