Posted 14 December 2023

How do you use a screw driver phase tester?

This might be a dumb question, but how do you use a screwdriver phase tester?
I purchased this one:
4262033-X2nyj.jpgOn Youtube I've seen people put it on sockets and on cables and it lights up.
But when I use it, nothing happens. Is there a trick to using it and does it only work on certain things? Thanks!
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  1. CurvedSlightly's avatar
    If you don't know, it's best you shouldn't know.
  2. VeganPolice's avatar
    Are you touching the metal bit at the end of the handle(blue bit in your photo) when testing? It is used to complete the circuit via you to the ground.
  3. TheUrbis's avatar
    Don't use one of these.

    Seriously.

    Get one of these (or a better one!) - screwfix.com/p/l….ds
    melted's avatar
    Maybe that lap one is better than the make I have, but I bought another make of those things once, and mine would often show live when the cable was isolated. Most likely false positives was it detecting either induced voltage, or via capacitance with light switch cables and the like.

    But, more alarmingly, occasionally it would show no-voltage when mains voltage was present.


    I came to the conclusion that I'd probably need to buy something premium like a fluke to get one slightly more trustworthy.

    I occasionally use a neon screwdriver just as a secondary check that there's no voltage. (edited)
  4. mds1256's avatar
    these are nicknamed death drivers....
  5. aLV426's avatar
    Firstly - it's NOT a phase tester, it does not test phases! All it can do is light up in the presence of an AC voltage >30 V when correctly connected.
    The end cap will have a metal contact on it - this is designed to work when you complete the circuit. You become part of the circuit and the current flows from the mains feed through the screwdriver, through you to ground and will give a faint glow.
    The reason why you shouldn't use one is not so much any potential (pun intended) risk of electric shock, it's more that it can not give a definitive answer as to whether or not a circuit is energised. Thus leading you into a false sense of no risk of electric shock or worse!
    Other versions use a battery and are usually marketed as a microwave detector as well.
  6. mutley1's avatar
    they are dangerous and should not be used.
    aLV426's avatar
    Can you explain why you think these are dangerous?
  7. Willy_Wonka's avatar
    As says above.

    If you have to ask on here & do not even know what it does then don't use it. These things are dangerous.
    aLV426's avatar
    Can you explain why you think these are dangerous?
  8. Gollywood's avatar
    I've got 3. I have no idea how to use it and never been interested
  9. powerbrick's avatar
    Is it left or right-handed?
    joyf4536's avatar
    Oh, you hold it in you hand
  10. Trooperman123's avatar
    a) Polite response - if you need to ask, suggest you get an electrician in
    b) Sensible response - it only works/lights on Live part of the circuit - have used assorted models over the years (inc. plug-in testers / multimeters - but doesn't mean circuit is 'dead' if not alight - Neutral may still be on (Live via SP or SPCO switch) and could still give a 'tingle' (or more) if you bridge N/E
    c) Silly response - who needs a screwdriver - stick your finger in the socket - if your hair stands on-end, job-done - that's the Live one
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