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How to Troubleshoot a Fuse Box

Hans Fredrick

In a home that uses a fuse box rather than a breaker box, every electrical circuit in the home will be connected to one of the fuses in the fuse box. The fuse provides a safety valve on the electrical current on that particular circuit.

Breaker boxes have replaced fuse boxes in most modern homes.

If the circuit becomes overloaded, or if there is a short on the circuit, the fuse will break. This stops the circuit and the power from reaching the outlets or devices that were previously powered by that circuit. In order to restore power, you need to know how to find the problem fuse in your fuse box and replace it.

  1. See if the power in the rest of the house still works. If only certain devices or the lights in a certain room have gone off, then you likely have a blown fuse.

  2. Locate the appropriate fuse in the fuse box. Fuses should be labeled. Identify the blown fuse by inspecting the fuses visually. Fuses in all devices, not just household fuse boxes, work by having a wire overheat and melt, causing a break in the circuit if the circuit becomes overloaded. When you inspect a household fuse, a blown fuse will appear to have a grey cloud on its surface. This is a fuse that needs to be replaced.

  3. Turn off the power to the fuse box if you have the ability to do so. Some fuse boxes will have a primary override switch that you can use to kill the power to the entire box.

  4. Unplug all the household devices that were plugged into outlets on the circuit that has the blown fuse. Also, turn off any lights on that circuit.

  5. Replace the blown fuse. Use a fuse that is rated for the same number of amps as the one that you are replacing.

  6. Turn the power back on to the fuse box, if you turned it off.

  7. Start plugging devices back in one by one. If your fuse blows again immediately, you should contact an electrician.


If you have a fuse box in your home, you should always make sure to have extra fuses of the correct rating on hand at all times. If your fuses are not labelled, you should systematically go through your house and remove the fuses one by one to see what parts of the house lose power. You can then create a road map of your fuses so you know which one to change in the event of a future power problem.


Fuse boxes are an outdated technology. Modern homes are instead built with a circuit breaker panel which is a safer and more efficient method of managing the electrical circuits in the house. If you're having ongoing problems with a fuse box, it is a very good idea to update the wiring in your house professionally, and move to a circuit breaker based system.