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HOME WIRING 101: DEALING WITH CIRCUIT BREAKERS AND FUSES

dealing-with-circuit-breakers-and-fuses

Repairs & Installation

HOME WIRING 101: DEALING WITH CIRCUIT BREAKERS AND FUSES

You don’t have to be a master electrician to own a home, but every homeowner should know the basics about how the electrical system in their house works and what to do when it doesn’t.

Whether you plan on tackling electrical wiring problems around your house or prefer to leave them to the pros, resetting tripped circuit breakers and replacing burned out fuses is something every homeowner needs to know how to do.

Understanding Electrical Service Panels

An electrical service panel is a metal box mounted on a wall or on the outside of your house which contains either circuit breakers or fuses to control the wiring in your home.

The panel may also include a main breaker or main fuse to turn off all the circuits controlled by the panel. If not, the main for the house may be located at the electrical meter or elsewhere in your home.

The purpose of circuit breakers and fuses is to limit the amount of electricity (expressed in amperes or “amps”) allowed to flow through the wires of an electrical circuit to prevent fires and electrical shocks.

The maximum number of amps allowed before the breaker trips or the fuse blows is printed on the breaker or fuse, and usually ranges between 15 and 30 amps for standard 110-volt circuits.

Make sure you are dry and standing on a dry surface before working on an electrical service panel or doing any other electrical work.

How to Turn Power On and Off to a Circuit

Each circuit should be labeled next to the breakers or fuses or on the inside of the service panel door to indicate which breaker or fuse controls the wiring to each part of your home.

If the circuits aren’t labeled, you’ll have to the flip the breakers or unscrew the fuses one by one until you find the one that controls the circuit you want to turn on or off.

To turn the power off to an electrical circuit, flip the breaker switch toward the outside of the panel or unscrew the fuse. To turn power to a circuit back on, push the circuit breaker switch toward the center of the box or screw the fuse back in.

How to Reset a Tripped Circuit Breaker

When a breaker trips or a fuse blows, it’s usually due to a power surge beyond the rated amperage of the breaker or fuse. This could be the result of:

  • An overloaded circuit with too many electrical devices on it.
  • Faulty wiring, such as a short in a wire or a connection that’s loose.
  • Short in an appliance, light fixture, lamp, or other electrical device.
  • Lightning or a power surge from the main line leading into the house.

It’s also possible that the circuit breaker or fuse itself is defective and needs to be replaced.

It’s important not to repeatedly reset a circuit breaker or replace a fuse, since it’s usually a sign of a problem with the wiring which needs to be fixed to prevent a fire or electrical shock.

To reset a tripped circuit breaker:

  • Turn Off Electrical Devices: If the breaker tripped because the circuit was overloaded, turn off or unplug any electrical devices on the circuit before resetting the breaker to prevent it from tripping again.
  • Locate Tripped Breaker: The switch on a tripped breaker will be near the off position or between the on and off settings.
  • Turn Breaker Off: Switch the breaker completely to the off position (away from the center of the panel box).
  • Turn Breaker On: Flip the breaker back to the on position (toward the center of the panel box).
  • Test Circuit: Turn on a light fixture or lamp on the circuit to make sure the circuit has power.

If the circuit continues to trip, there is either a problem with the wiring that needs to be fixed or the breaker itself is defective and needs to be replaced.

How to Replace a Blown Fuse

Unlike circuit breakers, fuses can’t be reset and must be replaced when they burn out.

To replace a plug type fuse:

  • Unplug Electrical Devices: If the fuse blew because the circuit was overloaded, turn off or unplug electrical devices on the circuit before replacing the fuse to prevent it from blowing again.
  • Locate Blown Fuse: Look in the window of each fuse at the metal strip inside. The metal strip on a blown fuse will be melted in two. Often the window of the blown fuse will be discolored or blackened as well.
  • Remove Blown Fuse: Unscrew a blown fuse by turning it in a counterclockwise direction. To prevent electrical shock, do not touch or insert tools inside the fuse plug socket.
  • Install New Fuse: Screw a new fuse of the same type and amperage as the blown fuse in the fuse socket in a clockwise direction. There are two types of threads for plug fuses, so make sure you have the right one for the socket.
  • Test Circuit: Turn on a light fixture or lamp on the circuit to make sure the circuit has power.

Electrical circuits that draw a lot of current, such as those for appliances, use cylindrical cartridge type fuses mounted behind pullout blocks in the fuse box.

To replace a cartridge type fuse:

Unplug Electrical Devices: If the fuse blew because the circuit was overloaded, turn off or unplug electrical devices on the circuit before replacing the fuse to prevent it from blowing again.

Remove Pullout Block: Pull on the handle to remove the entire pullout block from the fuse box.

Remove Blown Fuse: Remove the blown fuse from the pullout block. A fuse puller tool makes removing cartridge type fuses easier and prevents damage to the fuse.

Install New Fuse: Insert the new cartridge fuse, and push the pullout block back into the fuse box.

Test Circuit: Try turning on a light fixture or lamp on the circuit to make sure the circuit has power.

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