How to Find and Clear a Short on a "Fused" Circuit

You have a blown fuse. You remove it, screw in a replacement fuse and BAM! the new fuse also blows out. Something is blowing the fuse, but what? And you don't want to keep blowing additional fuses while trying to find the item that is causing the fuse to blow. What can you do?

  • For use in standard fuse panels only. It will not help with circuit breaker panels or "S" type fuses. (you will soon see why)


  1. 1
    Make a note / list of all the items that are not working on the circuit. (Lights and appliances)
  2. 2
    If you live near an Electrical Supply House go and purchase a 220Volt, 60 or 100 watt light bulb. A standard bulb will also work, but a 220 Volt bulb would be better.
  3. 3
    Remove the blown fuse and note the amperage. If you look at the bottom of the fuse, the amperage will be stamped into the center contact.
  4. 4
    If it is a 30 amp fuse and there are lights or outlets not working on the circuit, it probably is the wrong size fuse installed. (more on that later in this article).
  5. 5
    Screw the light bulb into the socket that had held the blown fuse. The bulb should light up. It may or may not be bright, but it will be lit.
  6. 6
    Now starting at one of the items (from your list of items that were not working) close to the location of the fuse panel, start unplugging items from the circuit / outlets. Do this, one item at a time.
  7. 7
    When you unplug the defective item, causing the short, the light bulb at the fuse panel will go off.
  8. 8
    If you have unplugged all the items on the circuit, and the bulb at the panel is still lit, then start turning off ceiling lights that are powered by the troubled circuit.
  9. 9
    Having found the defective light / appliance and it is still unplugged, it is time to replace the bulb at the panel with a standard fuse. Insert a fuse of the same amperage as the original blown fuse. You should be good to go at this point.
  10. 10
    If the blown fuse was a 30 amp fuse, it will be necessary to open the panel so that you can determine the proper size fuse to use for the wire attached on that circuit. 14 gauge wire needs a 15 amp fuse and 12 gauge wire needs a 20 amp fuse.
  11. 11
    If in doubt about the gauge of the wire, use a 15 amp fuse and see if it will hold the load.
  12. 12
    If your home has aluminum wire, use a 15 amp fuse on 12 gauge wire and 20 amp fuse on 10 gauge wire.
  13. 13
    If you have unplugged everything and the bulb at the panel is still lit, it is time to call an electrician for a more extensive trouble shooting job.

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Categories: Electrical Maintenance