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Ring Main at Consumer unit

Former Community Member
Former Community Member
My daughter has just had an electrical safety check done and I suspect that the electrician has been over zeleous..

Would anyone care to comment.


There is no grommet where the meter tails enter the consumer unit and the outer insulation stops just short of the knockout.

He has graded this C1.   Now my opinion is that that does not present an  an immediate threat to the safety of personell

It needs fixing but surely only a C2?


More intriguing.  He gives a C3 to the ring circuit because the two legs enter the consumer unit through separate knock outs.  I can't find that in the regs


And finally an old chestnut which has been discussed before.   A C3 because two radial "circuits" are served by a single breaker..  I have always argued that the definition of a circuit is that it is served by a single breaker.  Certainly if both radials were brought to a junction box outside the CU and then connected to the breaker by a single cable it would meet the definition of a radial..


Thanks for your attention

  • Former Community Member
    0 Former Community Member


    The caveats being the risk of the live meter tail pinging out of the main switch terminal and there may be some immovable cables exiting it.


    One would tighten the main switch terminals with a VDE screwdriver before starting work


  • 0
    dcbwhaley:

    Can the smart meter distinguish between the tails being disconnected or the main switch on the CU being opened?




    The smart meter detects the meter cover being removed to gain access to the tails terminals and sends an alert. It also detects the power to the meter going away (e.g. power cut or head fuse removed) and sends an alert. In the latter case if the DNO gets alerts from the whole street it assumes a power cut and comes out and fixes it. If just one house, it sends out someone to ask questions.


    It won't know about the CU main switch being open.


  • 0
    I now have a mental picture of these consumer unit tails, I suspect that originally they were pushed right into the consumer unit with the inner single insulation completely concealed and the grommet in place.


    A some time the tails have been yanked or dropped due to lack of support dislodging the grommet, exposing the inner single insulation and possibly stressing the terminations.


    Quibbling about if they warrant a C1 or several C2s is being pedantic, maybe it’s not a C1, but the outcome is the same, the report is stating it’s a mess that needs tidying up.
  • Former Community Member
    0 Former Community Member
    Sparkingchip:

    I now have a mental picture of these consumer unit tails, I suspect that originally they were pushed right into the consumer unit with the inner single insulation completely concealed and the grommet in place.


    A some time the tails have been yanked or dropped due to lack of support dislodging the grommet, exposing the inner single insulation and possibly stressing the terminations.


    Quibbling about if they warrant a C1 or several C2s is being pedantic, maybe it’s not a C1, but the outcome is the same, the report is stating it’s a mess that needs tidying up.


    Your analysis is almost certainly correct.  I suspect that the tails were disturbed during the installation of the smart meter..  And it certainly needs attention.

    But it is not a quibble, he outcome is not the same if the fault is a C1 as it would be if it were a C2


    If the fault is a C1 the family is advised, by the inspector, to immediately move out of the house to a hotel, put their animals in kennels, and not return until the faults has been rectified which could be several weeks.   If a C2 then they can remain in the house, taking care to avoid touching the CU until it is fixed.  Given the difficulty of finding an electrician to do the job that represents a considerable sum of money


  • 0
    The primary insulation of the tails can be seen or touched, that is your observation. The sheath IS NOT INSULATION, it is mechanical protection. There is no reason to suspect the primary insulation allows contact with live parts, the correct code is C3, requires improvement. This idea of moving out is complete nonsense, as is C1 or C2. The installation does not meet the requirements of the regulations but is not DANGEROUS. If you think this is dangerous, you and I have wildly different visions of reality. I assume you spend all day hiding in bed, unless damaged you cannot get a shock from LV insulation! It is untidy, and needs some work.


    Just for information, if these were HV cables at say 33kV you could get a tingle if the shielding were not connected due to capacitive coupling of a small current through the small capacitance to your hand, but you need a very high voltage to make this large enough to feel. Because you might jump back and fall this should probably be a C2, but not with 230V.
  • 0
    I agree moving out for a C1 is nonsense - for a real C1 the more usual response would be for the inspector to make it safe - either by switching off the affected part of the installation, or by effecting some temporary repair (perhaps applying a temporary barrier even wrapping with tape) or by agreeing some procedural work-around - e.g. my making sure all the adults in the house are aware of the problem and so know not to touch it and any children are kept away. In any event the inspector's responsibility is just to issue an unsatisfactory report and advice - what the response actually is is the customer's responsibility.


    I disagree about a C3 though - exposed basic insulation lacks fault protection (chapter 41) - so a C2 in my book.


       - Andy.
  • Former Community Member
    0 Former Community Member
    davezawadi (David Stone):

    The primary insulation of the tails can be seen or touched, that is your observation. The sheath IS NOT INSULATION, it is mechanical protection. There is no reason to suspect the primary insulation allows contact with live parts, the correct code is C3, requires improvement. This idea of moving out is complete nonsense, as is C1 or C2. The installation does not meet the requirements of the regulations but is not DANGEROUS. If you think this is dangerous, you and I have wildly different visions of reality. I assume you spend all day hiding in bed, unless damaged you cannot get a shock from LV insulation! It is untidy, and needs some work.


    Just for information, if these were HV cables at say 33kV you could get a tingle if the shielding were not connected due to capacitive coupling of a small current through the small capacitance to your hand, but you need a very high voltage to make this large enough to feel. Because you might jump back and fall this should probably be a C2, but not with 230V.


    I do not know who the "you" refers to in this post, but if itis me you are are misrepresenting me.  I am completly in agreement with you.  In my opinion the lack of sheath is a C3.  There are two other places in the installation where,, at socket entries, where primary insulation is visible and these have been graded C3

    The fact that there is no grommet and the primary insulation is in contact with the edge of the knock-out is a seperate and more contentious issue.   I have done an experiment with a piece of tail cable and an old back box and found it almost impossible to damage the cable on the edge of a bare knock-out


  • 0
    Basic insulation showing accessible to touch should be C2. Possibly not dangerous but there’s a layer of protection missing that was there for a reason. Is it potentially dangerous possibly depending on location, On this example you have a grommet missing and basic insulation on show so I would probably give a C2. All the guidance points to C2 but we haven’t seen it to make a judgment. A nice photo of the offending item would be nice.
  • 0
    How do the electrician preparing the report code any bayonet and Edison screw light fittings?


    By your own determination having any of these makes the house unsafe to live in, as they are a C1.

    https://communities.theiet.org/discussions/viewtopic/1037/28543
  • 0
    dcbwhaley:
     


    I do not know who the "you" refers to in this post, but if itis me you are are misrepresenting me.  I am completly in agreement with you.  In my opinion the lack of sheath is a C3.  There are two other places in the installation where,, at socket entries, where primary insulation is visible and these have been graded C3

    The fact that there is no grommet and the primary insulation is in contact with the edge of the knock-out is a seperate and more contentious issue.   I have done an experiment with a piece of tail cable and an old back box and found it almost impossible to damage the cable on the edge of a bare knock-out






    Worst case scenario:

    https://www.rqia.org.uk/RQIA/files/2e/2e609d70-0e41-4682-829b-83017c3bfcc8.pdf


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