Ensure safe operation of your electrical system with the right fuse
Fuses are used in everything from automobiles and computers to major
appliances and home wiring systems. Their primary function is to monitor
electrical currents and make sure they operate within safe limits for the type
and size of wire transmitting the current. If unsafe levels are detected,
whether due to overcurrents or short circuits, they break the connection to
prevent wire damage from occurring and to reduce the risk of electrical fires.
They are available in different styles and configurations, each designed to
meet the needs of specific applications. Before you go shopping for a fuse,
consider the following questions:
Types, Ratings and Selection
While fuses are used in a large number of applications, the most familiar are those found right at home. In older houses where the electrical panel has not been upgraded to accommodate circuit breakers, fuses are used to monitor and regulate electrical currents. These simple yet highly important devices are installed in a central fuse box where all electricity enters your home and branches off to other areas. Fuses contain a thin wire that allows the current to flow across them uninterrupted. If this wire exceeds the specified current level, whether due to overcurrent or a short circuit, it will heat the wire beyond capacity and cause it to melt, which terminates the circuit. This basic protection helps diminish the risk of electrical fires. Each fuse has certain ratings that determine at what level and how quickly the wire will melt. Learning what each of these measurements means is crucial to selecting the right fuse.
Plug Fuses: Plug-type fuses have a threaded base that looks like the base of a light bulb. Standard plug fuses are interchangeable, so it is very important that you match the specifications of the existing fuse to the replacement fuse. Inserting a fuse with a higher rating than the slot is designed to handle will permit much higher, and consequently more dangerous, current levels. Tamper-proof fuses provide protection against operating your system outside safe parameters by incorporating special adapters into your fuse box. These adaptors simply screw into fuse openings and only accommodate one size, making it impossible to insert a device that is not rated appropriately.
Cartridge Fuses: These fuses have a cylindrical body, typically
comprised of ceramic materials and ferrule contacts, or metal end caps. These
metal caps connect with a wire inside the body of the cartridge and, when
snapped into place on your electrical panel, complete the connection, enabling
the electrical circuit to flow freely. These fuses are often used for more
demanding applications, including running high-end household appliances such
as your water heater, range or clothes dryer, all of which feature electrical
motors that require more power upon startup. Some cartridge fuses are designed
for medium-duty tasks such as lighting fixtures and other devices without
Time-Delay and Dual-Element Fuses: With standard fuses, the internal
wire is designed to handle only a specific level of electrical current. When
that level is exceeded for any reason, the internal wire melts and the
connection is broken. In order to restore the connection, you have to replace
the fuse, which is costly and time consuming. This presents a particular
problem for circuits that support motor-driven appliances, since motors tend
to require an extra boost of power upon startup. Fuses with a built-in time
delay are designed to handle these types of situations without breaking. Fuses
that incorporate a dual element allow for even longer time delays by absorbing
extraneous heat and taking pressure off the main wire.
Ratings and Selection: In order to ensure that you are selecting the
right fuse, it is important to understand the significance of each rating
associated with the device. Consult the chart below for a simple breakdown of
important ratings, their meaning and key selection tips.
|Amperage||The level of electrical current the fuse can withstand without melting||
|Interrupting Rate||Determines the highest current at the rated voltage that must be reached before a fuse will break the circuit||
|Time-Delay||Determines how long the fuse can sustain an overload before breaking the circuit||
|Voltage||The maximum voltage a fuse is designed to interrupt||
Miniature Circuit Breakers: These devices look very similar to plug fuses, but are actually circuit breakers that have been designed to screw into standard fuse slots. They feature an external “reset” button that allows you to reestablish the circuit with just one touch. They do not need to be replaced.
Circuit Breakers: Most current construction projects no longer utilize fuses to control home electrical systems. They use circuit breakers instead, which function in much the same way, only they do not need to be replaced, just reset. You may want to consider hiring a professional to rewire your system to accommodate circuit breakers for increased convenience.
Adaptors: Fit standard plug-type fuse receptacles with appropriately rated adaptors that can accommodate tamper-proof fuses. These adaptors limit the size fuse you can put in place, ensuring that your electrical system is always operating within safe limits.
Multiple Fuse Packages: For fuse-based home electrical systems, it is advisable to keep multiple fuses of the same type on hand for easy replacement in the event of a blown circuit. Many manufacturers sell fuses in packages of five, ten or more for added convenience.
Automotive Fuses: Automotive fuses help regulate the electrical system in your car, truck, van or other vehicle. They are often referred to as “blade” fuses. These fuses feature a transparent plastic covering that allows you to view the internal wire so you can easily determine if a fuse has been blown.
For removing and installing cartridge-type fuses, bring home a special fuse gripper tool to make handling easier and safer.