Basic Functions and Use of A Digital Multimeter

Last updated on February 27th, 2024.

Diving into the world of electrical diagnostics, this post unlocks the essentials of digital multimeters. It’s more than just a quick glance; it’s your first step into understanding a tool that’s critical for any electrician apprentice. Let’s demystify the basic functions and usage of a digital multimeter together.

Here, we’ll break down what a digital multimeter is all about and guide you through its use. Plus, we’ll touch on various multimeter symbols you’ll encounter across different brands – a small detail that makes a big difference in mastering your tool.

What Is A Digital Multimeter?

A digital multimeter or DMM is one of the most useful items of test equipment to diagnose electrical or electronic problems. It’s a measuring device that takes analog information and uses an analog to digital converter to convert it into a digital signal which reads out on the display.

You can use a digital multimeter for measuring the following:

• AC voltage
• DC voltage
• Current (both AC current and DC current)
• Resistance
• Temperature
• Frequency
• Capacitance

Of course, this all depends on the type of digital multimeter you have. At a minimum, you should be able to measure voltage, resistance, and current with any digital multimeter.

How To Use A Digital Multimeter To Test Voltage

Testing a circuit (or source of power) for voltage is the most common use of a digital multimeter. Here’s how you would test different circuits for voltage.

DC or Direct Current Circuits

1. Install your test leads into the proper terminals on the meter. Black lead into the common or COM port and the red lead into the port labeled ∨Ω.
2. Turn on your multimeter and place the selector switch to the V with the solid and dashed line (VDC).
3. Now connect the test leads to the circuit: black to the negative potential point (which is the circuit ground) and red to a positive potential point.

   

You should now see a reading on the display. The display is now showing the voltage of the source (battery) or circuit. If you see a – symbol in front of the reading then switch your leads (this means the polarity is backward). If you don’t see a reading then check to make sure you’ve selected the correct setting and the leads and the leads are connected correctly. Still no reading? The source is either dead or the circuit is off. If it’s still not reading… then your multimeter is busted (make sure you get one of the best multimeters on the market… there is a lot of junk out there).

AC or Alternating Current Circuits

1. Install your test leads into the proper terminals on the meter. Black lead into the common or COM port and the red lead into the port labeled ∨Ω.
2. Turn on your multimeter and place the selector switch to the ∨ with the wave.
3. When it comes to AC, don’t sweat the lead placement—it won’t affect your measurements. What’s crucial is knowing the expected readings for conductors and receptacles, which we’ll guide you through understanding.

I found a  great video on YouTube that gives you a basic understanding of how to use a digital multimeter. For those of you who like to read, keep doing so.

I also found some great resources for you to check out if you need some more input. Fluke put together a digital multimeter fundamentals library that breaks down the DMM functions and how to use a DMM for certain applications. Check it out here.