How Does a Car Fuse Differ From a House Fuse?

They Differ but They're the Same

Automotive and house fuses differ. However, knowing how they're similar helps you to understand their function. Both kinds of fuses safeguard wiring circuits. In a home, a circuit may include wiring to the furnace and another for all the wiring in the kitchen. On a car, a circuit may include the heater and defroster and another for the horn and cigarette lighter. Both types of fuses are housed in a sort of home base; in a house it's the electrical panel, and in a car it's the fuse block. The fuses protect the wiring in the circuit by blowing before the wire heats up causing a fire. The wire in both the home and auto fuse is lighter and able to handle less of a load than the wire feeding the accessories or appliances. There lies its ability to safeguard the circuit.

System and Appearance Differences

Standard fuses for cars and homes always differ in one respect: Home fuses are threaded--screw in--and car fuses plug in. Home fuses operate under a system of alternating current, or AC, at a maximum of 240 volts. A car's alternator produces AC, which is rectified to direct current, or DC, to accommodate the 12-volt system of an auto. Home fuses are made of glass or ceramic material. The main fuse in a home is a cartridge type fuse and may handle as much as 400 amps, while the main fuse in a car would only be 50 or 60 amps. Car fuses are made of plastic and have many variations. They include mini, maxi and ATO which are plastic encased and two pronged.

Consequence of Failure

A major difference in auto and home fuses lies in what they protect. A house fuse failure, which should only happen because of tampering or product mislabeling, could cause a fire deep inside a wall. Total loss of a home could result. The same cause in an auto system most likely would only result in a wiring harness burning up. This is no small consequence but hardly the catastrophe of a house fire.

Differences in Size, Shape and Features

Some house fuses have a delay feature. Fuses tend to blow when appliances start up and draw the maximum amperage. This feature allows for this surge for a brief time without blowing. Automotive fuses don't have this ability. Car fuses are mostly flat and no more than an inch square. House fuses are round or cylindrical and an inch or less in diameter. Female car fuses push into pronged receptacles, while all house fuses either screw in, or in the case of main cartridge fuses, push into bracketed holders.