Detecting current in twin plus earth

Discussion in 'Electrics UK' started by Blitherer, 30 Jul 2011.

  1. Blitherer

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    I realise that one can use a current clamp meter to measure current in a single conductor, but is there anyway to measure current in twin plus earth without disconnecting it or cutting it?

    Thanks

    M.
     
  2. fireman22

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    well if you loosen the accesory box you can use a mini clamp meter and clip it around one of the live conductors, i have done this to test immersion heaters inside the switched spur, otherwise outside say a twin & earth the answer is no
     
  3. holmslaw

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  4. Wontdothatagain

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  5. holmslaw

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  6. doni

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    "Unlike conventional clamp meters, the Megger MMC850 Multi-core Clamp Meter has a complex array of planer magnetic sensor coils to calculate the current flowing in the conductors of multicore cables with either 2 cores or 3 cores, and in either flat or round section cable, up to 100 A. The convenience and potential time saving from using the Megger Multi-Core Clamp is considerable."

    ?
     
  7. fireman22

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    must admit i havent seen one of these, does anyone know how accurate the reading it gives is?
     
  8. martinxxxxxx

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    I don't think Megger would lie so consult the MI online, someone might do it for you.
     
  9. cumbriahandyman

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    Not sure of the accuracy but at up to £145 each + £25 for a calibration cert, they are not for the DIYer.
     
  10. JohnW2

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    They claim that it has a resolution of 0.1A and an accuracy of 5% + 10d, such that it is 'reasonable' for currents in the range 2A - 100A, but pretty useless for currents <2A.

    I've seen talk of these before, and must say that I'm rather intrigued by the described technology, and rather surprised that it can give anything approaching accurate results; at the least, I would have expected it to be very orientation-sensitive.

    Kind Regards, John
     
  11. fireman22

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    i wasnt saying megger would lie i just meant how accurate is reading as the jaws have a centralising bit and wondered how critical it would be to have a true reading on a flat twin & earth cable, has anyone used it?
     
  12. RF Lighting

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    Just knocked this together in my workshop

    [​IMG]

    :D
     
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  13. martinxxxxxx

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    That is brilliant, thanks for going to the trouble and to think I couldn't even be bothered to do a google for the MI.

    I have a question are all of the instuments "in calibration"? Oh and I can't read the left hand one. :oops:

    Thanks Martin

    PS we'll have to think of more things for you to knock up and photo - your experiments are one of the best things about this forum - that someone is prepared to do something practical to add to a discussion. Well Done
     
  14. EFLImpudence

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    It says 01.9 as well.
     
  15. RF Lighting

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    Unfortunately none of the instruments are calibration. I have never needed a clamp meter that is bang on accurate, so con't justify £40 a year on it.

    The load was a 500W halogen lamp, so the readings are possibly a little on the low side, but they are near enough.

    The meter on the left says 1.9A too. It's my meter I use at work and has got quite sratched so is a little difficult to read in the picture.
     

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