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smart meter cuts off supply (?)

Discussion in 'Electrics UK' started by SparkyTris, 18 Jul 2021.

  1. SparkyTris

    SparkyTris

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    an elderly female neighbour was concerned that her EV charger (installed outside) no longer had a flashing blue light on it so asked my brother (who happened to be visiting at the adjacent property) to "have a look".
    also she had said that her smart meter usage monitoring panel had been displaying "no network" or some similar message.

    as part of "having a look", the Push To Test bar on the Ottermill ELCB (see photo) was pressed, which caused the ELCB to operate and the regular supply to the dwelling house was interrupted (viz, the lights went out)

    Resetting the ELCB did not restore supply.

    At this point the professional electrician who installed the EV final was called and he attended rapidly, and diagnosed that the smart meter had cut off the electric supply.

    does the smart meter have a designed function for disconnecting supply? seems like a bit of a problem if this can happen.
     

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  3. ericmark

    ericmark

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    Athough smart meters can turn off power, we are told this is disabled, so seems more likely main fuse has ruptured.

    It seems to have wylex MCB's and I think the old Wylex main isolator is rated 60 amp which limits the DNO fuse size to 60 amp so unless there is a current clamp to turn off the charger if total exceeds 60 amp then very likely the fuse will be over loaded and rupture.
     
  4. SparkyTris

    SparkyTris

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    Report from the electrician was, power is getting to the smart meter but not beyond it. Not sure how he could have diagnosed this definitively without disrupting DNO equipment, but that's apparently wot 'e said
    I think my brother would probably have noticed the main fuse rupturing. I must admit I've never been around when one goes but it is probably "noticable" is it?
    probably the smart meter would tell you if there was no volts?
     
  5. JohnW2

    JohnW2

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    Does the 'smart' meter perhaps have some sort of LED indicator which remained lit to indicate that it was receiving power? If not, as you say, he would have to have done something "which he shouldn't do" in order to come to the stated conclusion (but he certainly would not have been the first electrocution, or non-electrician, to do that - if he did)!

    Kind Regards, John
     
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  6. SparkyTris

    SparkyTris

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    if a smart meter like the one pictured contains the facility to disconnect power, how is this achieved?
    the unit in the picture does not appear big enough to comfortably house a contactor of say 100A capability
     
  7. SparkyTris

    SparkyTris

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    I wondered similar. It is "smart", so I guess that it could display verbose messages etc describing how it feels about what it's connected to.
    I further wondered whether a volt-stick neon proximity gadget could have been used for his diagnosis which may have led to mis-diagnosis.
     
  8. JohnW2

    JohnW2

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    All of them apparently do, but suppliers seem to have agreed (if one believes them) not to use that facility.

    I suspect that you may be over-estimating how physically big a 100A contactor actually needs to be, influenced by the size of the standalone ones we are used to seeing. If you think about it, the actually 'switching parts' of, say, a 100A RCD, or a 63A MCB, take up relatively little actual space.

    Kind Regards, John
     
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  9. JohnW2

    JohnW2

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    Agreed on all counts.

    Kind Regards, John
     
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  11. JohnD

    JohnD

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    Smart meters contain several anti-tamper devices; one might have been triggered.
     
  12. bernardgreen

    bernardgreen

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    Inside a "Smart" Meter

     
  13. ericmark

    ericmark

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    I have been trying to find out what the type D RCD is this thread some 14 years ago did not answer the question, however it is clearly 60 amp, so the DNO would be irresponsible to fit over a 60 amp fuse, reading the info on Zappi charge points it seems they do a version to monitor total power used, however to do that it would need a device likely a current transformer before the supply splits, and I can't see one, neither can I see any reading on the meter which makes one think likely dead.

    7kW is 30 amp, so in essence that means a 30 amp supply to house, I have lived in a caravan with a 10 amp supply so one may get away with 30 amp, but it would depend on when the car is plugged in compared with other items, I know when we arrive home, we tend very soon after to cook food, oven, couple of microwaves and an induction hob could easy take much of the 30 amp left, and going for a shower would really cause problems.

    So would still say most likely DNO fuse ruptured.
     
  14. SparkyTris

    SparkyTris

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    that Ottermill Type D ELCB (not a RCD) is fairly simple I believe, but (being an ELCB) it only works on actual earth current flowing in one particular earth path. I imagine that they were used on an installation that comprised a possibly bad local earth spike. Ive known the district in question (M20 corridor high ground) for years and Im sure it used to be overhead supply so probably TT with local earth so that would hang together. Not sure whether they have officially changed to PME but it certainly is PME on the adjacent property. (although the DNO never removed the fossilised earth spike which had been there since startomatic days when they put the latest PME head in)

    The thing is, that the supply was lost when my brother tripped that ottermill ELCB and never came back.

    The pic shows that the ELCB has nothing to do with the EV charger (the EV charger is fed off the CU in the lower LHS of snap)

    I mean he effectively introduced a momentary earth fault on the house supply, and that has caused total loss of juice. I believe DNO wranglings are ongoing at present. the lady has been without mains overnight now. OK in warm weather but a different story in january, probably.
     
  15. Chunky19

    Chunky19

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    The Ottermill is another name for a Chilton voltage operated elcb. Not an RCD. In fact it’s printed on front. See better pic attached. Also the earth entering at the bottom and exiting at the top tells us nothing as the electrode terminal and frame terminals are bus bared from top to bottom and may(or may not) be connected through to trip mechanism. Ie. attached to same top and bottom. This would mean it’s just an isolator. As for the loss of supply and how the spark tested we don’t know yet.
     

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  16. SparkyTris

    SparkyTris

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    "voltage operated"
    interesting.
    I have yet to meet anything mechanical that is "voltage operated"
     
  17. Sir-John

    Sir-John

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    Best you look up what the term means in that contex then.
     
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