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diy:electrical_faults

troubleshooting electrical faults

Introduction

  • any electrical repairs on circuits with voltages higher than 30V should be done by a qualified electrician!

No power

  • troubleshooting:
    • is it just one device?
      • check the power cords are plugged in correctly and the correct power switch is turned on
      • is there a local circuit breaker for that power switch - if so check it
      • consider removing the cord for 20secs and then re-inserting to “reboot” the device
      • does the device have a fuse - this may be blown
      • try a different power point in case it is an issue with that power point or that circuit
      • otherwise it may be a device failure
    • is it just one power board?
      • you may have over-loaded it and triggered the circuit breaker or fuse on the board
      • remove devices, reset the circuit breaker and try again avoiding excessive wattage or current load rated for that board (usually 2400W in Australia)
    • is it just one circuit in the house?
      • most likely cause is either the circuit breaker or RCD have tripped - check the circuit board and then see below for troubleshooting
    • is it the whole house?
      • check you neighbours - it may be a local blackout
      • if your house is the only one - check you circuit board main power switch
        • if the circuit board seems fine, perhaps your power company has stopped supply due to unpaid bills or a power company issue

Circuit breaker tripped or fuse blown

  • this is due to an excessively high current occurring and is usually caused by either:
    • short circuit
      • this is generally caused by faulty wiring or faulty electrical device
    • excessive power load current draw
      • most household power circuits in Australia are rated to 10A 240V = 2400W (some circuits are rated to 15A such as kitchen ovens)
      • if you exceed 2400W on one circuit then the fuse will blow or circuit breaker will trip
    • lightning strike
      • this would be a rare cause and likely to trigger all circuit breakers or fuses
  • troubleshooting:
    • check devices on that circuit to ensure they are not combining to give excessive wattage
    • turn all devices off on that circuit, turn circuit breaker back on
      • if it trips immediately then there is a short circuit in the wiring from switch board to the power points
      • if it doesn't trip, sequentially turn on all power points on that circuit
        • if one trips it then that is the fault
        • if it hasn't tripped then try sequentially running each device on the circuit

RCD earth leakage safety device triggering

  • this is due to detection of current leaking to ground from either the active or neutral wires
  • NB. circuit breakers, fuses and power switches are generally breaking the active line of an AC circuit - thus if the RCD is still tripping despite all these being OFF, then the issue is likely to be a faulty RCD device or less commonly, a persistent neutral line to ground leak (these do not generally create enough current to trip an RCD but could do so)
  • this is usually caused by either:
    • if occurs after new RCDs installed:
      • new RCD is more sensitive than older ones and thus may trigger when the old one didnt from low earth leakages of 30mA
        • clamp-meter the earth or neutral to measure leakage milliamps with the appliance running before trip, to see how close to 30 mA it is
      • MEN/earth bars are not configured correctly for your board layout
      • neutral being shared with other RCDs - this is particularly likely if BOTH RCDs have tripped at the same time (both do not need to trip for this fault to be present)
    • a faulty appliance
    • damaged insulation on wires
    • exposed neutral wire contacting ground (could be an active wire but without enough current to trigger the circuit breaker or fuse)
    • moisture near electrical wiring
    • faulty RCD device
  • troubleshooting
    • you may know what caused it by it happening as soon as an event happened such as turning a device on or house maintenance where wiring may have been affected
    • turn off all circuit breakers that are controlled by that RCD
      • if RCD still won't reset to ON, then it may be either:
        • a neutral wire leaking current to ground
        • a faulty RCD device
      • if RCD resets to ON, then sequentially turn back on the circuit breakers
        • if the RCD is triggered when turning on a circuit breaker then the fault is in that circuit
          • turn all power switches off on that circuit
          • if the RCD still trips when turning that circuit breaker on, it suggests a neutral wire leaking current to ground
          • if RCD resets stays ON when the circuit breaker is turned on then sequentially turn back on the power switches on that circuit
            • if the RCD trips when turning a power switch on then the device connected to that switch is faulty
            • if RCD resets stays ON then you may need to run a device on that circuit to see if the device is causing the issue
diy/electrical_faults.txt · Last modified: 2026/02/17 23:01 by gary1

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