A fuse is an electrical safety device designed to self-destruct in case of a power surge and other overcurrent situations. The critical function of an electric fuse is to save the rest of the circuit from power surge damages. Replacing a blown fuse is less costly than replacing an entire circuit damaged during a power surge incidence.

Common Causes of a Blown Fuse

Let us look at the ways to check if your fuse has blown and how to replace it:

Identifying a Blown Fuse

Method 1

Step 1: Remove the fuse from the circuit before you subject it to a continuity test.

Step 2: Choose an ideal multimeter and select a resistance setting or continuity setting.

Step 3: Touch the leads together until you hear a beep or see 0 ohms.

Step 4: Next, power off the circuit and place the leads on either side of the fuse. Should you hear that same beeping sound, and the meter has a very low resistance reading, the fuse is still good. However, if there is no beeping sound and the multimeter is reading OL, it is enough indication that the fuse is blown.

Method 2

Alternatively, test the fuse by measuring the voltage using a digital multimeter. This method comes in handy when testing a fuse that cannot be easily removed from the circuits. Use the following steps:

Step 1: Power the circuit and switch the meter.

Step 2: Select DC for DC circuits and AC for AC circuits. You should also ensure you are not exposed to dangerous voltages. Wear recommended protective gear.

Step 3: Put the meter leads on each side of the fuse. If you notice slight to no voltage registered, the fuse is okay. However, if you notice a huge variation in voltage, the fuse is faulty.

Replacing a Faulty Fuse

When replacing a blown fuse, go for one with identical specifications. However, before you replace the fuse, determine first if it is a slow blow fuse or a fast blow fuse. It is a common practice to replace a slow blow fuse with a fast or slow blow option. Slow blow fuse is popular in inductive circuits such as motor starting. Notably, using a slow blow fuse will allow for a higher current tolerance for a short period.

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