1. Visiting from the US? Why not try DIYnot.US instead? Click here to continue to DIYnot.US.
    Dismiss Notice

Continuity

Discussion in 'Electrics UK' started by Gasman1015, 10 Jul 2006.

  1. Gasman1015

    Gasman1015

    Joined:
    22 Mar 2005
    Messages:
    646
    Thanks Received:
    1
    Location:
    Devon
    Country:
    United Kingdom
    Circuit is 2.5 / 1.5
    Tested at DB
    Cpc / Cpc 0.34
    Neutral / Neutral 0.05
    Phase / Phase 0.05

    R1 + R2 0.25

    The figures seem to be all over the place, was testing before making alterations, Trying to calculate the circuit length.

    0.34 x 1000 = 340 / 12.10 = 28 metres
    0.05 X 1000 = 50 / 7.41 = 6.74 metres

    Double checked readings five times, zeroed meter, still pulling my hair out.

    Could use some experienced views please.
     
  2. Sponsored Links
  3. Lectrician

    Lectrician

    Joined:
    18 Jul 2004
    Messages:
    8,515
    Thanks Received:
    406
    Location:
    Devon
    Country:
    United Kingdom
    Not using a fluke 1652 are you? :rolleyes:

    Instinct says the L and N seem a little low - are you sure the leads are correctly zero'ed? The CPC value seems about right for a standard sized ring. It could be simply that the CPC is a little high resistace, due to a dodgy termination somewhere.

    Where in Devon are you?
     
  4. RF Lighting

    RF Lighting

    Joined:
    31 Mar 2006
    Messages:
    19,990
    Thanks Received:
    1,354
    Location:
    Leeds
    Country:
    United Kingdom
    It sounds very fishy.

    How big is the area served by the ring circuit?
    These are the readings before you carried out any work?
    The readings (as I presume you realise) sound wrong. It strikes me that someone may perhaps have tried to extend a ring and got it wrong?

    Whatever the cause, it needs further investigation, and at least you have covered your a**e by finding there is a possible fault before you modified the circuit
     
  5. dingbat

    dingbat

    Joined:
    29 Sep 2003
    Messages:
    2,846
    Thanks Received:
    68
    Location:
    West Midlands
    Country:
    United Kingdom
    It sounds very much to me like you've incorrectly nulled your test leads. Un-null them and take the circuit readings again. Then measure the resistance of the clips, several times if necessary. When you've got a reading that is repeatable and makes sense, subtract that and then see if your circuit length calculations work out.

    (And take heart that at least you realised there was something wrong - plenty would have just written down the values as measured and thought nothing of it.)
     
  6. Sponsored Links
  7. Gasman1015

    Gasman1015

    Joined:
    22 Mar 2005
    Messages:
    646
    Thanks Received:
    1
    Location:
    Devon
    Country:
    United Kingdom
    Firstly, thankyou for the replies.

    No, I have'nt made any alterations yet. I wanted to be sure of the condition of the circuits beforehand. I test everything before starting, comes from experience with gas installations.

    Really not 100% confident with my test meter Megger MFT1502, ten months old, anyone want to buy it, absoluteley certain of it being zeroed, I suspected loose connections, will return to job later in the week, everything isolated at the moment, owners live abroad.

    Large three bedroom terraced property, expected ring to be about 50/60 metres, 11 points, 1 circuit for down and upstairs.

    Will maybe try to borrow another meter. I'm in Torquay.

    Would really like to try out the Fluke, but are they any better than the Megger.
     
  8. Bright_Spark

    Bright_Spark

    Joined:
    23 May 2006
    Messages:
    95
    Thanks Received:
    0
    Location:
    Yorkshire
    Country:
    United Kingdom
    i use alphateks stuff. theyre owned by metrel and i find their stuff good

    www.alphatek.co.uk if ur interested.
     
  9. Gasman1015

    Gasman1015

    Joined:
    22 Mar 2005
    Messages:
    646
    Thanks Received:
    1
    Location:
    Devon
    Country:
    United Kingdom
    Thanks, seems they are not up and running yet.

     
  10. Pensdown

    Pensdown

    Joined:
    17 Jan 2006
    Messages:
    2,439
    Thanks Received:
    3
    Location:
    Kent
    Country:
    United Kingdom
    Because our fluke 1652's were in for null faults on a regular basis we thought we would try the megger CM500. Nice piece of kit but it measures low by about 0.4ohm. It's brand new out of the box and it is supposed to be calibrated.

    Gasman's post highlights the problems with test kit because if you don't trust the readings then you don't know if there is problem with the installation or not. 10/10 Gasman for spotting the irregularities.

    I would suggest that a few more circuits should be tested either on site or at home and if the readings are all suspect it may be the test kit.
     
  11. DIYnot Local

    DIYnot Local

    Joined:
    3 Sep 2019
    Country:
    United Kingdom

    If you need to find a tradesperson to get your job done, please try our local search below, or if you are doing it yourself you can find suppliers local to you.

    Select the supplier or trade you require, enter your location to begin your search.


    Are you a trade or supplier? You can create your listing free at DIYnot Local

     
Loading...

Share This Page