Older homes or wiring systems may still rely on fuses as part of the electrical system. The most important aspect of fuse systems to keep in mind is that you never want to use a fuse that has an amperage rating higher than that specified for the system. The continuity of fuses can be tested by touching one probe of a multitester to the center contact and the other to the screw shell. If the reading is zero, the fuse is working properly.
The low-voltage fuse is usually used in electronic appliances and entertainment gadgets. This type of fuse is available in ratings up to 20 amperes. This type of fuse is capable of signaling either a short circuit in the wiring or an overloaded circuit.
Standard Plug Fuse
The standard plug fuse is the kind found in most service panels. These plugs power the circuits of basic lighting fixtures and small appliances. The standard plug fuse is available in ratings of 15, 20 and 30 amperes to suit the gauge of wire in the circuit. This fuse can signal a short circuit or an overloaded circuit.
Time Delay Fuse
The time delay fuse is also found in most residential service panels. This fuse is used for power-hungry small appliances and is available in ratings of 15, 20 or 30 amperes. The time delay component means that this fuse is capable of withstanding short power surges due to things like the startup of a motor. The time delay fuse also can signal short circuits, overloaded circuits and sustained circuits.
The Type-S fuse is found in service panels and is used for powering up light fixtures and small appliances. The difference between a standard plug fuse and a Type-S fuse is that it can guard against accidental installation of a fuse with higher amperage rating. Type-S fuses are available in ratings of 15, 20 or 30 amperes to suit the gauge of wire in the circuit. The fuse fits an adapter that is screwed into the service panel. This adapter accepts only Type-S fuses of matching amperage.
The ferrule-type cartridge fuse can also be found in fuse-type service panels, and it is used for powering major appliances. The ferrule-type fuse cartridge is available in ratings up to 60 amperes to suit the gauge of wire in the circuit. This type of fuse is capable of withstanding momentary power surges through the circuit and can signal an overloaded, short or sustained circuit.
Knife Blade Cartridge Fuse
The knife blade cartridge fuse is available in ratings of more than 60 amperes. This fuse is used to protect the electrical system of the household and can withstand momentary power surges.