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Discuss Multimeter showing reading when nothing is plugged in in the Electrical Tools and Products area at ElectrciansForums.co.uk.

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  1. Klaudmjj
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    Klaudmjj New EF Member

    Location:
    West Midlands
    I want to talk about the context to this first, I'm in my first year at college studying level 2 electrical installation and for Christmas my family got me a toolkit which had some tools , multimeter and a soldering iron. They didn't really know much about things like that and they wanted it to be a surprise so the quality isn't so good, here is the exact tool kit: ZD-961_Tool Kit_Products_Ningbo Zhongdi Industry & Trade Co., Ltd. - http://www.china-zhongdi.com/product/291.html

    Okay so I was messing around with the multimeter, turned it to AC voltage, and measured a socket to see if it works. It did, came up with 233v. Then I wanted to measure the amps in the socket, so I changed it to the 10A max , put the test leads inside and theres a big flash , big boom and black around the black test lead and the socket.
    I then look at the multimeter, switch it to "20 DC voltage"and it shows a reading although nothing is plugged in , same for "AC volatage" and "Amps" so far the ohms setting is normal.

    Now I think what I did wrong, the AMPS had a DC symbol next to and I tried to measure AC or/and the socket is over 10A.

    Is there a way to fix my multimeter, or am I better off getting a new one?
     
  2. Wilko
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    Wilko Electrician's Arms

    Location:
    Berkshire
    Business Name:
    Wilko Electrics
    Oh dear, that the end of that meter I think. Have you worked out why this has damaged the meter?
     
  3. Pete999
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    Pete999 Forum Mentor

    Location:
    Northampton
    Business Name:
    None
     
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  4. ElectroChem
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    ElectroChem Industrial Controls Electrician

    Location:
    Sydney. Australia
    Business Name:
    Automated Control Solutions
    That multimeter is dead. You could possibly replace a fuse but I'd never trust a reading from it again.

    The more worrying point is that you don't appear to understand why it went bang, or that sockets don't have 'amps' in them. I'd strongly suggest getting further into your course before you start poking test leads into anything.
     
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  5. StephenRowley
    Online

    StephenRowley Regular EF Member

    Location:
    Leeds
    Lucky you didn't you didn't electrcute yourself tbh. Those meter are very cheap and certainly not rated for dealing with mains voltages, there barely worth bothering for Low voltage stuff

    There CAT rating won't be good enough for dealing with mains voltages, the probe won't meet relevant standards either.

    You also need to learn how to use multimeter properly you need to measure current in series with a load. When you've tries to tried to measure across the socket you've in effect shorted live and neutral hench the bang. A decent quality meter would have just blown it's fuse but as you've got a crappy meter it's fried.
     
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  6. Jim_e_Jib
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    Jim_e_Jib Regular EF Member

    Location:
    Devon
    When you measure voltage with a multimeter, the input resistance of the meter is very high - of the order of 1M ohm or more to avoid loading the circuit and causing voltage drop so you get an accurate measurement of the voltage as it would be without your meter connected. This means that a very small current flows and you don't get a big flash and bang when connecting across L and N or L and E.

    When measuring current, the input resistance of the multimeter is very low - typically less than 1 ohm so you get an accurate reading of the current flowing in the circuit as it would be without your meter connected. Connect this across L and N (or E) on a typical 240v socket circuit and you will get a massive current flowing that will blow the fuse in the multimeter or, as it sounds in your case, will fry the multimeter.

    As @StephenRowley@StephenRowley said, you need to measure the current with a load connected and the multimeter in series with load.

    At some point on your course you may cover test instruments and how to use them - I would hold off on any experiments at home until you have covered this and are happy with how to work safely.
     
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    Last edited: Dec 31, 2018
  7. static zap
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    static zap Regular EF Member

    Location:
    west midlands
    Plenty avoid meters with an Amps ranges , as it acts like a piece of wire , designed to pass current .
    A cheap clamp meter will only measure larger AC amps but stay alive a lot longer .
     
    • Agree Agree x 3
  8. littlespark
    Offline

    littlespark Electrician's Arms

    Location:
    Scottish Borders
    Multimeters are only really good for 2 things.... testing low DC voltages.... batteries and car electrics.... and continuity ie fuses.

    Anything else, don’t trust ‘em
     
    • Agree Agree x 1
    • Disagree Disagree x 1
  9. Andy-1960
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    Andy-1960 Electrician's Arms

    Location:
    Wolverhampton
    As the old saying goes.. a little knowledge is a dangerous thing!
     
  10. Massive1
    Offline

    Massive1 Trainee Access

    Location:
    southend
    This will defiantly be taught within your level 2 where series circuits having the same current and parallel circuits having same voltage and which instrument is used to measure.

    In fact it will more then likely come up in your exam

     
  11. Vortigern
    Offline

    Vortigern Electrician's Arms

    Location:
    England
    Business Name:
    F.H. Electrical
    Just goes to show, you should read the instructions! It would have told you DO NOT connect to mains in that mode.
     
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  12. Timbo
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    Timbo Regular EF Member

    Location:
    Sussex
    Business Name:
    TechFix Services
  13. Strima
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    Strima Electrician's Arms

    Location:
    St Neots
    Nothing like learning the hard way... :D
     
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  14. Archy Styrigg
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    Archy Styrigg Forum Mentor

    Location:
    Manchester
    I can't deny it, I did laugh when I read the OP :D
    Fortunately he wasn't hurt.
     
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    • Agree Agree x 1
  15. Timbo
    Offline

    Timbo Regular EF Member

    Location:
    Sussex
    Business Name:
    TechFix Services
    With all due respect to the OP's family, I would put that lot straight in the bin!
    At the very least never use it!
     
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