How to measure amps in a circuit? Measuring current with a multimeter

Multimeters are used to measure current, voltage and all kinds of electrical variables. To measure amps in a circuit, however, requires more care and attention. Because it's actually the amperage that gives you an electrical shock. The amperage of any circuit depends upon its voltage sources. There are two types of voltages AC and DC. So, there is a different procedure to measure current in DC and AC circuits.

What are the Amps?

Amp is basically a unit of current and is commonly known as ampere. The amperage of any circuit shows the power or capacity of any electrical equipment. 

Now, you know the importance of amps. So, now you’re ready to measure amps in any circuit. 

You can measure current with both multimeters and clamp meters. Current in both AC and DC circuits with a digital circuit but the only thing you need to know is that the circuit is energized or dead. I have also made an in depth comparison between clamp meters vs  multimeters to make it easier for you to understand their working.

There are two ways to measure current: 

Direct measurement: 

Direct measurement measures current at the point where it enters the circuit. For this purpose, you can use a multimeter or clamp meter.

Indirect measurement: 

Indirect measurement measures current at some point outside of the circuit. This can be done by using an ammeter or voltmeter connected to two different points in the circuit.

Tools required to measure current

  • Screw Driver
  • Multimeter or Clamp meter
  • Insulated Gloves

Step by step guide to measure AC/DC current in a circuit

As a first step, you should know what the amp rating of the circuit is. Now you have roughly an idea of the value to be measured. Now you have to select the multimeter. A standard multimeter can measure current up to 10A (A=amps). So, if you want to measure current in ac circuits above 10 amps then you need a clamp meter. 

In AC circuits you can measure current only in series with a multimeter. For this purpose all you have to do is,

  • First of all, Turn off the main voltage supply.
  • Set the multimeter to (A~) ac measurement as shown in fig.1.
  • Now Insert the Positive lead(Red) in the A jack and the negative test lead(Black) in the common jack.
  • After inserting the leads, connect the multimeter with load in series. 
  • If you’re not aware of how to connect in a series then keep reading.
  • To connect your multimeter with load in series, attach the one test lead (red) with load and the other test lead (black) with source voltage negative terminal.
  • Now turn the power supply the results will be shown on the display of your digital multimeter in Amps.
  • In the case of analog multimeters, the procedure will remain the same but now you have to see the results through the moving needle.
range of multimeter

fig. 1

Measuring DC amps (current) in a circuit

Measuring DC amps in any circuit is almost similar to AC amp measurement. But in DC measurements you have to attach your multimeter in series only on Positive voltage lead. Because the current in DC circuits flows mostly through positive leads and the negative lead is mostly used as common for inner PCB earthing. So, if you want to avoid any false reading or want to avoid any ghost voltages then choosing the positive voltage lead will be a wise option. Now all you have to do is choose the right clamp meter. I have also made a list of TOP CLAMP MULTIMETERS FOR ELECTRICIANS, which may suit your requirements.

How to measure current in a circuit with a clamp multimeter?

Next to the digital multimeter is the clamp meter which simplifies measuring current. No matter which circuit it is, AC or DC, it's possible to measure the current without opening the connection. 

A clamp meter is basically a multimeter with a clamp type jaw coil. You can clamp any wire with this opening jaw. This coil acts as a secondary coil and the current-carrying conductor or cable acts as the primary coil. After this, the clamp meter controller reads and shows the current flow through the cable on display.

To measure current in a circuit all you have to do is select the amp (A~) option and clamp the conductor. But you can clamp only a single insulated or naked cable at a time. 

If you have an insulated cable with live and neutral wire then strip the insulation to clamp on a single wire. 

3 Best multimeters for how to check amps in a circuit

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KAIWEETS HT118A

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Klein Tools MM700

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Being an engineer I love to use multi-purpose tools. Choosing Klein tools MM700 is the main reason of it. I have also compare Klein MM700 with Fluke 117(The market Giant) for you. You can also choose mm400 for routine use.

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Amazon Commercial (6000 counts)

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6000 counts display,  high voltage and current measurements what else you need from this robust multimeter. No matter, you want it for automotive use or home use it is an ultimate choice.

3 Best clamp multimeters to check in a circuit

Conclusion (How to measure amps in a circuit)

Most people do a very common mistake of measuring current like other electrical variables. You may even lose your life by making this mistake. So, if you want to do it on your own then you must have to choose the right multimeter and know how to measure current in a circuit.

If you’re still with me then you might have a clear idea about how to measure it properly without risking your life. Now all you have to do is choose the right multimeter (see the best multimeters for home use). Furthermore, if you’re still confused then it's better to call an electrician for this purpose. 

FAQs-Frequently Asked Questions

How to measure current in an electrical circuit without power?

Current is basically the flow of electron charges in the electrical circuit. If the circuit is off then you can not measure the amps because the net result will be zero and your multimeter will show zero value.

Compared to measuring voltage, how do you measure current?

While measuring voltage you have to select the AC/DC voltage range and use “V” and “Com” jacks for test leads insertion. Furthermore, for voltage measurement, you have to connect positive and negative test leads in parallel. But in the current measurement, you have to connect the DMM in series with the load otherwise you will see a voltage drop. Another difference between voltage and current measurement is the test lead jacks, in current measurement you have to insert test leads in A~ and Com jacks.

Which measuring device is best for electrical components?

You can either use a digital multimeter, an analog multimeter, ampere meter or a clamp meter for measuring amps in any electrical system. All you have to do is to choose the right range. The best tool to measure voltage is a digital multimeter but to measure current clamp meter is the best option. Because with clamp meters you can measure current up to high ranges.

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