How to Measure Amps Using a Multimeter

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How to Measure Amps Using a Multimeter

If you are using any electronic gadget, amperage is one of the things you need to check to determine the amount of current flowing regularly. For example, if an element in your vehicle is draining your battery, you can conduct an amperage test in such a case. A multimeter is the best tool to use when measuring amp. 

A multimeter is an electronic device used to measure resistance, voltage, current, and other values. Multimeters are of two types; a digital and an analog multimeter.

I. Analog multimeter

As the name depicts, this multimeter uses analog procedures to exhibit measurement readings. Analog multimeter has a progressed scale and a needle that moves over it. These kinds of multimeters are mostly used to detect slow voltage variations.

II. Digital multimeter

It is an electronic multimeter whose measurements readings display on a screen. They are preferable due to their high accuracy, high digital resistance, and the fact that they are easy to read. 

Measuring amps using a multimeter is quite easy. This article explains the procedure you need to follow to measure amperage with a multimeter. Here are the simple steps you need to follow. 

a) Multimeter configuration

  • Check the plate on your breaker or battery to know its highest amps.

It’s necessary to ensure that the multimeter can measure the sum of amps flowing through the circuit before attaching it to the circuit. Every power source has an approximation of the highest amperes. Therefore, it is important to check from the instruction manual the maximum amps that the multimeter can handle.

  • If your multimeter is not rated adequately high for the circuit, it is necessary to use a plug-in immobilizer.

The advantage of using a plug-in immobilizer is because it can widen the amps range. You need to connect the probes into the multimeter and connect the other end to the circuit. Then place the immobilizer around the live wire. The immobilizer, though, does not share in the circuit.

  • Connect the negative probe to the common outlet on the multimeter.

The multimeter has two probes, a negative probe that is black, and a positive probe, which is red. The negative wire’s probe should be connected to the socket, and the other probe connected to the meter. 

  • Connect the positive probe in the outlet marked ‘Amp.’

There are many ports to plug in the red probe. However, the socket marked ‘Amp’ will give amperage readings. The port can have a label of “10Amp,” which measures amperage of up to 10 amps, or “mA” which measures up to 300m amps. If you are not sure the best to use, it is recommendable to choose the higher 10A or A.

  • Select DC or AC on the multimeter.

You need to select the current range you are testing unless the multimeter is intended to use a specific DC or AC circuits. Always check the plate on the power source if you are not sure of the current to use.

  • Set the knob to an amp higher than the amp of what you are measuring.

When you check the highest currents, you are to test, turn your dial higher than those currents. To be safe, set the dial to the highest possible current. However, you may not attain the reading if the current you are measuring is much lower. If this happens, turn down the dial and have the measurement again. Some dials range automatically; therefore, you do have to adjust it manually. 

b) Testing the amperage

  • Ensure power running in the circuit is off. 

Disconnect the negative probe running from the battery if the battery powers your circuit. Alternatively, if the power is from the breaker, turn the switch off and then detach the negative probe. It is essential to take precautions when handling electricity. Avoid handling open wires using bare hands.

  • Detach the red cable that is drawing current from the power source. 

For you to get the sum of the current flowing over the circuit, you need to connect your multimeter to a complete circuit. Start by switching off the voltage in the loop and then disconnect the red wire, which carries the positive polarity. Then connect the multimeter in the circuit to complete it. Note, if the circuit does not have clips on the red wire, which you can unclip a connect you multimeter, cut open the circuit. The process is referred to as breaking the course.

  • Remove the coating on the edges of the positive wire 

When using the alligator clips, uncoating the cable is not necessary as you will squeeze then through the rubber. If you don’t have the prongs, you can attach the wires by winding them on each other. The aim here is to have a complete circuit. You can add to your prongs wire if they are short.

  • Connect the red wire to the positive multimeters probe

The naked edge of the wire coming from the power end should be connected to the positive probe. The connection should be firm to avoid inaccurate readings. The necessity of connecting the red wire to the positive probe is to get a positive reading on the multimeter. In case you connect the positive cable to the negative probe, the readings will be negative. You can assume the negative sign on the screen or interchange the probes.

  • Connect the other end of the wire to the negative probe.

The other end should be connected to the negative probe. Now current will run from the source to the powered compartment through the multimeter. The current is what we want to measure. Note that any power that is not now in the circuit should be off to avoid blowing the multimeter. For example, if what you are measuring is on a vehicle, the engine’s vehicle should not be running.

  • Switch on the circuit

The current will flow from the battery (source) through the multimeter and then to the appliances. There are readings that will be detected on the screen of the multimeter. The readings may be unstable immediately. The circuit is powered on, but after some seconds, it will stabilize to a fixed value. The value displayed is the amperage that is in the circuit

Conclusion

You can now conduct the test confidently by yourself if you follow the above guide. Note that if the reading on the screen of the multimeter is below the range setting, i.e., the range setting goes up to 3A, and the reading you get on the screen is less than 0.3A, you will have to shift the multimeter to read mA.

About the Author Dan

Just a random guy who likes to build things. Providing tool knowledge, appliance/device testing tips, and DIY project info in an easy-to read & non-intimidating style.

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