A fuse is a safety device designed to provide protection for an electrical circuit. When there is a surge or too much current flows through a circuit, the fuse's primary component, a metal wire or strip, burns up or melts. When this happens, the flow of electricity within the circuit is cut off, thereby preventing any potential fires or damage to electrical components.
Two of the most common fuses are the cartridge fuse and the blade fuse. The cartridge fuse, which has been around for years, is a cylindrical fuse used in a wide variety of devices, from small electronics to homes. With a metal contact or terminal points on either end, a cartridge fuse is basically a tube that contains the wire. The blade fuse has been in use for about 20 to 30 years now and is a common type of automotive fuse. It has two metal prongs protruding from a plastic housing which contains the wire, and it plugs conveniently into banks. Because of its small size, blade fuses take up little space so many of them can be incorporated into a single fuse bank.
Whether in the house, car, or truck, when they do what they're designed to do, a burned-out fuse needs to be replaced since it's a one-and-done safety device. When replacing a fuse, there's a fast and easy way to test that the new one is in good working order by simply using a multimeter.
A multimeter measures electrical resistance, AC and DC voltage, and electrical current flow. To test a fuse, a multimeter can be used either as an ohmmeter, which tests resistance, or an ammeter, which tests the flow of current. When testing current flow or resistance in a circuit, the multimeter, which has a negative and positive test lead, transmits a small quantity of electricity from its own battery. It then measures the amount of electricity that passes through the circuit.
To test a fuse, make sure the vehicle, electrical equipment, or device is turned off. Then simply pull the fuse straight out of the fuse bank or slot in which it is installed. Often you can simply just look at a fuse to see visually if it is still functioning. They're typically clear so you can see the wire within, and if the wire is intact, the fuse most likely is in good working order. With a fuse that has done its job, often the clear wire housing will have a black stain on it after the metal wire or strip within has burned out.
With the fuse removed you're now able to test it, so turn on the multimeter and rotate the meter's dial to OHMS, or Ω, to measure the resistance. Before testing the fuse, touch the tips of the black and red test leads of the meter together. The number that appears on the readout should be close to the one you'll see when you test the fuse. Before you test, however, it's important to place the fuse on a non-conducting surface such as laminate, plastic, or wood. Now, place the tip of each test lead on either end of the fuse at the terminal points; it doesn't matter which end the black or red one touches.
The reading displayed should match, or at least be a close match, to the reading displayed when you touched the tips of the test leads together. If so, the fuse is good. If there is no reading at all, the meter may display OL for "Open Loop," which means the fuse is blown and is no good and should be replaced.
Though small in size, a fuse does a big job. And testing them to ensure they're working properly can save you from major problems, not to mention major expenses.
Product Compliance and Suitability
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