Always replace a fuse with the same rating as (or a lower rating than) the old one. Prepare the Multimeter. Open the box door and turn on the flashlight to inspect the fuses. Regarding car fuses, most cars use a colored 'blade' type fuse, and looking at the top of the fuse in situ in the fuse box will show that the metal strip that runs along the visible top of the fuse will either be intact (fuse good) or broken (fuse blown). You can use it to check any positive circuit, from your cigarette lighter to your headlights and taillights. Fuses provide protection against overloading, short circuits, or device load, etc. Fuses come in different styles, cartridge, and screw-in. If you want to use the meter as an ammeter, keep reading! What do I do if the reading is 00.00 when I touch the leads to the ends of the fuse or together? Breaker Tripping Frequently or Not Staying Reset. Turn off the main power switch to disconnect power to the fuse box. Touch the probes to both end of the fuse. A good fuse would have shown zero volts. If you get no reading or “OL”, then the fuse has blown. When working with anything electrical, shut the power off to the device that you'll be working on and check with a tester to make sure it is not live. Ricardo has over 10 years of electrical and construction experience and his partners have over 30 years of relevant experience. A fuse provides protection for each of your electrical circuits by stopping the flow of current if an overload or fault occurs. Testing fuses with a multimeter is comparatively simple to do, and the equipment involved is cheap and easy to operate. Understand fuses. This will measure the resistance of the fuse link, if intact. If it is, then the fuse works properly. In either way, you need to locate the... Test the fuse. Then put the probes on either side of the fuse and check if the reading is similar. Perform a quick test of the meter to ensure it’s functioning properly by touching the leads together until you hear a … Most plugs will have a fuse inside them. Step 2. Turn the car off, if it is on, and then locate the car's fuse box. Plug fuses have a metal alloy ribbon inside that carries the current of the circuit. Do not overload plug sockets by using multiple plug adaptors.Replacing the plug on an appliance is fairly straightforward, and is well worth doing before you declare your electrical appliance broken.Warning: 1. When the circuit in your home quits working, and you suspect that it is likely a blown fuse, you can test that theory by using a multi-meter for testing fuses. Blade fuses plug conveniently into banks, and relatively little space is required to house a large number of them together. How to Reset a Circuit Breaker. Once you have located the poles, take the probes and place them on the negative and positive sides of the... Additional check. A fuse incorporates a fuse link that has a specific amperage rating, usually 15, 20, or  30 amps. It is usually grey in color and mounted near the outdoor AC unit. In addition, most car parts can only be tested at repair shops, and to do so will usually cost quite a lot of money. They have metal contact or terminal points on either end and consist primarily of a tube that contains the wire. Touch the metal caps at each end of the fuse with the metal tips of the testing leads. If you want to measure the ohms, use the multimeter setting that has the omega symbol (Ω). Cars and older homes that don’t use modern circuit breakers use fuses to prevent damage from electrical surges. Never test a fuse on equipment that is still on. The blade fuse is a common type of automotive fuse that has come into use in the last 20-30 years. Step 3: If the wire is broken, replace it with fuse wire of the same amp rating. Ensure to make good contact by touching a clean metal surface on each cap. The Spruce uses cookies to provide you with a great user experience. It is easier to test fuses than it is to test other electrical equipment. If a fuse is rated at .5 and the meter reads .3, is this a bad fuse? L ocated inside or outside of your home is a fuse box that contains a fuse for each of your home's circuits. wikiHow marks an article as reader-approved once it receives enough positive feedback. Watch for … We use cookies to make wikiHow great. This article has 11 testimonials from our readers, earning it our reader-approved status. CN Coterie specializes in full home renovation, electrical, plumbing, carpentry, cabinetry, furniture restoration, OATH/ECB (Office of Administrative Trials and Hearings/Environmental Control Board) violations removal, and DOB (Department of Buildings) violations removal. Household installations these days shouldn't really be protected by just fuses. If too much power runs through the fuse, it will "burn out," quite literally, and open the circuit, preventing the current from flowing through the circuit. Please help us continue to provide you with our trusted how-to guides and videos for free by whitelisting wikiHow on your ad blocker. Place the fuse on a non-conducting surface such as wood, laminate or plastic. % of people told us that this article helped them. Attach the clip for the test light to any bare metal, and use the probe of the test light to touch each end of a fuse. There are 2 tests we can use to check to see a fuse is good or blown. Great stuff, many thanks. Cartridge fuses come in a cylindrical shape and have contacts points at each end. This type of protection is in place to keep your home from having an electrical fire. Put on a pair of rubber-soled shoes and make sure the area around the circuit box is dry. With the ignition switch in the ON position, touch or clamp the black test lead to a good known ground. Before you test the fuse, you need to know what it is about. Ricardo Mitchell is the CEO of CN Coterie, a fully licensed and insured Lead EPA (Environmental Protection Agency) Certified construction company located in Manhattan, New York. The newer style, Edison-based, have a plastic thread with a spring-type contact and a center contact. If it doesn’t trip again then the problem is too many things on one circuit, or a single appliance—like a portable space heater—that draws more current than the rating of the breaker. Now that we know the basic terminology, we finally come to the steps to test a fuse using a multimeter. Exactly what I wanted. Evaluating Electrical Loads Again, you should see the … When a fuse is broken, it reads the circuit is not complete, so it reads an open line. In the case of a short or overload, causing too much current to flow, the ribbon will melt and open the circuit. To test a fuse simply touch one lead to each of the electrical contacts on the fuse; if the light bulb lights up the fuse is good. Visual Test of a Fuse. The Ferrule-type fuses are rated up to and including 60 amps. If the fuse can be removed from the circuit, then the easiest way to determine if it has blown is a continuity test. Modern circuit breakers and protective devices are fuse-less and much safer. They have a fuse link connected to the two ends and are rated for 240-volt circuits and protect the circuit from over-current. Open the fuse box and locate the offending fuse or fuses. We know ads can be annoying, but they’re what allow us to make all of wikiHow available for free. Introducing "One Thing": A New Video Series. Cartridge fuses come in a cylindrical shape and have contacts points at each end. Open the door on the fuse panel and look for the fuse you want to test. Many types of fuses allow for visual confirmation that the fuse is still functional. Timothy Thiele is an electrician who advises residential DIYers on how to make home installation projects safe and easy. If the multimeter reads "Open" or "Not complete," it means the fuse is broken. By setting the selector switch to ohms and setting it on a lower range, you can test the resistance between the two points of the fuse. It's big brother, the knife-blade cartridge fuse, is similarly shaped with blades on each end. It only allows the appropriately sized fuse to be installed, unlike the old style that you could install a 30-amp fuse in a 15-amp socket. With the main power still off, unscrew the blown fuse and remove it. It mimics the shape of the fuse and snaps over the fuse for easy removal. If the positive path is intact, you can also use the test light to check the grounding points of the circuit. By using our site, you agree to our. Ricardo has over 10 years of electrical and construction experience and his partners have over 30 years of relevant experience. Touch the red test lead to the first metal square, then to the other. What is the acceptable level of ohms for a fuse to be considered good? They come in 15, 20, and 30-amp sizes and are screwed into the electrical panel. Here is the part on how to test a fuse. Learn what each of these fuses is and how to test each of these fuses below. Check the labeled area that corresponds to the part of the house that lost power. If you’re using a digital multimeter set to measure resistance, touch the probes together to get an initial reading. This article was co-authored by Ricardo Mitchell. I would recommend lowering your power source's output through resistors or adding additional places for electricity to flow. This article has been viewed 712,848 times. All fuses have two terminals, positive and negative one. ", "It was precise and to the point. Inspect the socket, which is very similar to a lamp or light socket and locate the single standard screw in the very bottom. If the appliance suddenly stops working, it is worth replacing the fuse inside the plug before calling an electrician.To find out the correct type of fuse to fit in the plug, check the rating plate on the appliance. Get a voltage tester that’s rated for up to 500 volts. While resetting it, the tripped breaker clicks as you … wikiHow is where trusted research and expert knowledge come together. A blown fuse may be discolored, cloudy, or have a melted or broken metal piece inside. The Edison-type base has an advantage over the older style. Smaller and newer buildings have the cylindrical fuse which has some sensitive links at its ends, wrapped with copper or any other type of conducting material. So if you get 00.00 your fuse is good. Fuses take time to heat up and blow, and when that happens, you have to purchase and install replacements. A homeowner can determine if a glass fuse in blown by performing a visual inspection and looking for a break in the thin wire and a brown discoloration in the center of the fuse. Your home's electrical wiring must be protected from short circuits and circuit overloads. Plug fuses are common fuses used in a home's fuse panel. Plug fuses are common fuses used in a home's fuse panel. On the end cap of a blade fuse, you'll see two exposed areas of metal designed for testing. The best way to test for a blown fuse is by using a voltmeter. This protects against short circuits and overloads that may damage electrical wiring and cause house fires. ", "What volt meter setting to touch both leads was helpful.". Testing the fuse using a multimeter Locate the terminals. Cartridge fuses are cylindrical and have the contact points at either end. Ricardo Mitchell is the CEO of CN Coterie, a fully licensed and insured Lead EPA (Environmental Protection Agency) Certified construction company located in Manhattan, New York. A ceramic fuse, however, shows no damage upon visual inspection. Thanks a million. Open the door of the service panel and see if a circuit breaker is tripped (or a fuse is blown). There is no polarity so you can use any lead for either fuse cap. By using The Spruce, you accept our, How to Troubleshoot and Fix Holiday Christmas Lights, How to Determine the Size of Your Main Electrical Service, 4 Reasons Why Circuit Breakers Trip and Fuses Blow, Using a Neon Circuit Tester to Check Receptacles for Proper Grounding, How Electrical Service Panels Have Evolved, How to Turn Off the Power at Your Home's Breaker Box or Fuse Box, Calculating Electrical Load Capacity for a Home. If the fuse is good, the test light will light up on both sides of the fuse. They come with a sight glass that shows if the fuse is blown or not. ", "I wasn't sure how to test my household's cylindrical fuses, you showed my how. To verify that you have a blown fuse on hand, the first step is to locate the disconnect box. It won’t burn off … Manually test the breaker first. Testing a ceramic fuse is the only way to tell if the fuse has blown. test a fuse and hopefully save me hundreds of dollars in repairs by just replacing a blown fuse. To double-check that diagnosis, try disconnecting some of the electrical loads on that circuit, reset the breaker and wait a few minutes. Grab a multimeter and select the continuity or resistance setting. Get daily tips and tricks for making your best home. If the translucent area is blackened, it is. Step 4: Reinstall the fuse and turn the main switch back on. Well, your circuit is putting out too much power for your multimeter to read. Just as the wiring is sized specifically for the load it can handle without breaking down and heating up, so works the fuse. Using a volt meter and basic car knowledge you will be able to test all your circuit breakers with relative ease. Using a test light to check a fuse that appears not to work but changing the connection to a positive source touching the same fuse and the test light goes on. There are thousands of different types of fuses, but they all essentially perform the same function. This article was co-authored by Ricardo Mitchell. Thanks! They are made clear so that you can see if the wire remains intact. ", "Found out that the door was not closing properly, no electrical/electronic was burnt. When this happens, no current can flow, and the circuit is disconnected from the power supply. This article really helped me on how to, "This article instantly gave me the info I needed with the minimum of extraneous detail. Some homes have more than one circuit breaker panel, there may be a main panel plus one or more sub panels in other locations. If the fuse is bad, only one side will illuminate the test light. The meter will read OL if the fuse is bad. Any reading other than OL or a blank screen tells you the fuse is good. Lay the rubber mat on the floor in front of the fuse box and stand on it. Now, you need to locate the blown fuse. These fuses supply the branch circuits in your home to run lights, outlets, and appliances. If a fuse blows does that mean there's problem with the amp? L ocated inside or outside of your home is a circuit breaker panel (sometimes called a fuse box) that contains circuit breakers for each of the circuits in your home. This is because the blown fuse allows there to be a voltage differential between the two sides. When testing resistance in a circuit, the meter will transmit a small quantity of electricity from its own battery and then measure the amount that passes through the circuit or object. A reading of 00.00 ohms means there is (almost) no resistance, which you would expect from touching the leads together and from a good fuse. These testers are available at most home improvement or electronic supply stores. They control the amount of amperage to the circuit it connects to. {"smallUrl":"https:\/\/www.wikihow.com\/images\/thumb\/e\/e1\/Test-a-Fuse-With-a-Multimeter-Step-1-Version-4.jpg\/v4-460px-Test-a-Fuse-With-a-Multimeter-Step-1-Version-4.jpg","bigUrl":"\/images\/thumb\/e\/e1\/Test-a-Fuse-With-a-Multimeter-Step-1-Version-4.jpg\/aid650234-v4-728px-Test-a-Fuse-With-a-Multimeter-Step-1-Version-4.jpg","smallWidth":460,"smallHeight":345,"bigWidth":728,"bigHeight":546,"licensing":"