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Discuss Multimeter - basic continuity test in the Electrical Tools and Products area at ElectrciansForums.co.uk.

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  1. Filby66
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    Filby66 New EF Member

    Location:
    London
    Hi

    I'm a product design student working on a project and am looking to get some advice.

    I would like to buy a cheap test instrument that can carry out the following earth continuity test.

    Maximum resistance 0,50 ohms measured by passing a minimum current of 10 A at between 6 V and 12 V for at least 1 second.

    Basically the component is two pieces of metal held together with machine screws. The metal has been powdercoated and I have removed some paint under the screwhead. I want to check enough paint has been removed so that it would pass the above test.

    Would a cheap multimeter be able to do this?

    I have looked at continuity multimeter videos on youtube but I can't see how you can set amps and voltage on the continuity setting.

    Many thanks
     
  2. Gavin John Hyde
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    Gavin John Hyde Electrician's Arms

    Location:
    Somerset
    Business Name:
    Sulis Electrical Services Ltd
    assuming you are at a proper college/uni where they do meaningful degrees and not mickey mouse courses,head down to the science lab where they do the physics or engineering courses, you will find all the kit you need down there
     
    • Agree Agree x 3
  3. PEG
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    PEG Trusted Advisor

    Location:
    Manchester
    I suspect a cheap multi-meter is going to require a jump-start pack:)
     
  4. Matthewd29
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    Matthewd29 Regular EF Member

    Location:
    Belfast
    I nice shiny new megger will do that for you
     
  5. davesparks
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    davesparks Trusted Advisor

    Location:
    guildford
    A portable appliance tester maybe, but most other testers won’t put 10A through the circuit.
     
  6. davesparks
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    davesparks Trusted Advisor

    Location:
    guildford
    You won’t buy a cheap new tester that is capable of such a test current.
    Multimeters will produce a tiny test current, and a continuity tester used for general electrical installation testing normally tests at 0.2A.

    How specific do the test conditions need to be and how accurate the results?
    If not too specific then a portable appliance tester would normally have a test function which passes up to 25A to take a resistance measurement.
    Second hand portable appliance testers are often quite cheap on sites like eBay, but are unlikely to be calibrated.

    Alternatively you could hire a high current ohmmeter, also known as a ductor, low reading ohmmeter or DLRO which will be capable of doing the test with good accuracy.
     
    • Like Like x 1
  7. Filby66
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    Filby66 New EF Member

    Location:
    London
    Many thanks for the replies. I'm sure the university will have the equipment I was just wondering if there was something I could use at home. Just a quick question - what difference would it have on the result passing 25A to take a resistance measurement (using a pat tester as in the previous post) compared to 10A (the requirements of the test I would like to carry out)

    *Just to be clear please don't worry I'm not wiring anything or anything like that it is just for a design project.
     
  8. telectrix
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    telectrix Scouser and Proud of It Trusted Advisor

    Location:
    cheshire/staffordshire
    Business Name:
    Telectrix
    passing a higher current would better highlight any poor continuity. PAT testers cand do this as they use a low (non-lethal) voltage.
     
    • Winner Winner x 1
  9. davesparks
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    davesparks Trusted Advisor

    Location:
    guildford
    in This application there is unlikely to be a difference in using either test current as long as the item under test can conduct 25A for the test duration without overheating.
     
    • Agree Agree x 1
  10. Filby66
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    Filby66 New EF Member

    Location:
    London
    Ok that makes sense. Many thanks for explaining.

    I have borrowed a Seaward PrimeTest 100 which gave a reading of: Rpe 0.06Ω.

    On the back of the primetest it states the following:

    Range:
    Rpe (+/-200mA) 0.05-20Ω
    (Uq>4VDC/In>200mA)

    Riso (500v) 0.5-20MΩ
    (Un>500VDC/lk<2mA)

    Leakage (RMS)
    Class 1, 0.25 - 10mA
    Class 2, 0.1 - 3.5mA
    Cord, 0.1 - 3.5mA

    I was wondering if someone could advise what current and voltage the PAT tester used to carry out the test.

    Thanks again
     
  11. davesparks
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    davesparks Trusted Advisor

    Location:
    guildford
    looks like 4Volts and 0.2Amps, presumably that’s a battery powered tester?

    I’d forgotten those things existed when I suggested a PA tester, I was thinking of the proper mains powered ones which use a decent test current.
     
  12. Filby66
    Offline

    Filby66 New EF Member

    Location:
    London
    Yes about the size of a shoe and takes 6 batteries haha!
     
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