All residential electrical systems have built-in failsafe measures that interrupt the flow of electricity during overload or malfunction. Many older homes have fuse boxes. Modern homes have circuit breaker boxes instead. Although the two serve the same purpose, they work much differently.
What Is a Fuse Box?
Fuse boxes are metal boxes that function as the central hubs of older electrical systems. They’re often referred to as distribution boards (DBs). Fuse boxes are usually located in basements, laundry rooms, utility rooms, or outside. However, you may find your home’s fuse box in your attached garage, mudroom, or crawlspace.
In their interior, fuse boxes have six to 12 cartridge-style and screw-in fuses. Cartridge fuses are cylindrical fuses for high-voltage circuits. Screw-in fuses correspond to each room or electrical service area. A fuse box should have separate cylindrical fuses for each high-voltage appliance, including refrigerators, washing machines, heaters, and air conditioners.
Overloaded Fuses Burn Out and Must Be Replaced
Fuses move or power electric current over thin strips of metal. During power surges, overload, and electrical malfunction, the current moving across these strips exceeds their limitations. When they melt, electric current can no longer pass through them and fuses are no longer viable. Melted strips break circuits to prevent problems like electrocution and electrical fire. To restore the current, homeowners must remove blown fuses and install new ones.
Main Fuse Blocks
Every fuse box also has a main fuse block. Removing this block cuts the flow of electricity throughout an entire building. Firefighters and other first responders might pull a fuse block before entering a home to eliminate electrical hazards. Homeowners and contractors should pull fuse blocks before working on or servicing hardwired electrical features and appliances. Main fuse blocks are typically located at the top of fuse boxes and just off to one side.
Fuse blocks have exposed metal components. Following electrical overload and other types of electrical malfunction, this metal is often hot to the touch.
What Are Circuit Breaker Boxes?
Like fuse boxes, circuit breaker boxes are small metal boxes that serve as the hubs of residential electrical systems or their main electrical panels. Although circuit breaker boxes are sometimes installed outside, they’re usually found in utility rooms, closets, garages, or hallways. Rather than fuses, breaker boxes have two rows of circuit breakers with each breaker corresponding to an individual service area or high-voltage appliance.
What Happens When a Circuit Breaker Trips?
Like fuses, circuit breakers have metal strips for detecting electrical overload and electrical malfunction. However, the bi-metal strips in circuit breakers bend rather than melt when subjected to increased electrical current. Bending movements trip breakers, open their breaker switches, and block the flow of electricity.
To reset a tripped breaker, homeowners must simply toggle its breaker switch back into the “ON” position. Since there’s nothing to remove and replace, resetting a tripped breaker can be much easier than changing a blown fuse in the dark.
Main Breakers
To cut off your home’s entire electrical supply, there’s no need to remove a potentially hot fuse block when you have a circuit breaker box. Instead, you can toggle your electrical panel’s main breaker switch. These larger switches are typically located at the top or bottom of service panels, and they’re functionally identical to the smaller breakers for individual appliances and service areas.
Are Circuit Breaker Boxes Safer?
Although it’s not illegal to have a fuse box in an older home, it’s not always practical, safe, or convenient. In many areas, fuse boxes are not compliant with local electrical codes, and homes that have them may have a hard time passing lender-required inspections.
Arc-Fault Breakers
Circuit breaker boxes have arc-fault protectors that detect and prevent fires caused by electrical arcs in wiring. Also known as arc-fault interrupters, they offer added protection that fuse boxes lack.
Differences in Amperage
Most fuse boxes supply 60-amp power. Circuit breakers can supply 100-amp or 200-amp power or greater. Thus, among the biggest drawbacks of having a fuse box rather than a circuit breaker is being unable to install and safely support many modern and essential appliances. For instance, although you can install a central air conditioner if you have a fuse box, it’s generally recommended to upgrade your electric panel first. Installing modern appliances on old fuse boxes can result in frequently blown fuses and shorter device lifespans.
Corrosion and Other Age-Related Problems
In addition to their lower amperage, fuse boxes are more susceptible to corrosion than circuit breakers, especially when they’re installed in basements, crawlspaces, or outdoor locations. Moisture and humidity can rust fuse contacts and cause poor connections and frequently blown fuses.
Over time, moisture, fluctuating temperatures, and other wear can erode or loosen connections within fuse boxes. These changes in integrity diminish performance and create the risk of electrical fire.