How to identify a faulty circuit

This guide tells you how to identify a fault in an electrical circuit. Note that if you are not able to solve the problem following the steps below the problem will be down to more than just a blown fuse or broken socket or switch. If this is the case, you will either have to employ a qualified electrician to diagnose and fix the issue or do the work yourself and notify Building Control afterwards so they can check the work for safety.

Level of difficulty

Level 2: Intermediate

What you need

  • Fuse
  • Screw driver
  • Screws
  • Circuit tester
  • Switch / socket

The steps to follow

Note:

  • A faulty circuit is mainly due to an overload which causes a blown fuse. In this case, you'll have to change the fuse or reset the breaker.
  • You can unplug the appliances one by one to locate the source of the problem.
  1. Turn off the mains power.
  2. Unplug one appliance at a time and turn the mains power on each time to see if it is the unplugged appliance that's causing the problem.
  3. If the fuse blows or the circuit breaker trips when the power is turned on, then you've just identified the appliance which has caused the overload.
  4. Turn off the mains power again and remove the appliance from the circuit.
  5. Turn the mains power back on. If the fuse has not blown or the circuit breaker has not tripped, then you've found the problem. Turn the mains power off and locate a different circuit where you could re-plug the appliance.
  6. If the fuse still blows, then the problem may be in the circuit itself. To repair the circuit, you'll need to get the help of a registered electrician to repair it.

Sometimes the problem lies in a switch or socket. If this is the case:

  1. Turn off the mains power.
  2. Undo the switch or socket plate and test for any open current with a circuit tester.
  3. Check for any loose wiring and replace any damaged wiring. You might need to replace the whole socket or switch in order to fix this problem.
  4. When the switch/socket is replaced, test to see if it is working properly.
  5. If the fuse still blows, after having checked the circuits individually, you'll need to check the entire circuit for any loose or burnt wires.

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