How to Read a Multimeter?

It’s a common misconception that all electricians need to be able to read an electrical meter. Fortunately, this is not the case. 

If you’re starting as an electrician aspirant or if you’re interested in getting into the trade, then you might want to know how to read a multimeter before reading on.

The first thing you’ll notice about a multimeter is that it has two probes sticking out of it, and either one can be used for testing voltage, amperage, or resistance. 

Both probes must be there because some measurements require more than one probe; they also need a power connection using at least two wires. The three main types of readings are voltage (V), current (I)

Multimeter Basics

A multimeter is a handy tool that you use to measure electricity, just like using a ruler to measure distance, a stopwatch to measure time, or a scale to measure weight. 

Unlike these other tools, though, it can also be used for measuring different things — kind of like having many multi-tools in one! Most models are designed with an adjustable knob on the front, letting you select what type of measurement needs doing – such as current voltage and resistance.

How to measure using multimeters?

Almost all multimeters can measure voltage, current, and resistance. See the next section to explain what these terms mean for your convenience! For instructions on making measurements with a multimeter, click on the Using a Multimeter tab above. 

Some models have an audible continuity check that will emit a loud beep if two things are electrically connected; this is helpful when building circuits or soldering wires in place as it indicates everything has been appropriately completed before proceeding further. 

You may also use it to help prevent short-circuits by checking whether objects are not connecting improperly, which could potentially cause harm later down the road.

Knowledge of diodes and their functions is crucial to designing circuits. A diode acts as a one-way valve, only allowing electricity to flow in its intended direction. 

Some multimeters have this handy feature if you’re unsure which way your component should be plugged into an electrical circuit or how well they are functioning correctly. If yours does, read through its manual before using this function to know exactly what it can do for you!

If you’re in the market for a multimeter, consider which features are vital to your needs. For example, if you want one with many different functions, such as measuring and identifying other electrical components like transistors or capacitors, then an advanced model might be perfect!

Volts, Amps, and Ohms

Before you start fiddling with your multimeter, it’s essential to understand a few basic concepts about electricity. 

  • Volts measure the voltage or amount of force “pushing” electrons through a circuit. If we use our common analogy of water flowing downstream and imagine that volts are like the pressure behind this flow; 
  • amps represent how much current there is about these voltaic pushes – so if more rushes past an obstacle (such as when lightning strikes), then its amp-rating will be higher than before. 
  • Ohms measure resistance within circuits: the greater their level, which indicates less power being passed along them because they’re slowing things down

Measure Voltage Using Multimeter

Follow these steps to measure the voltage with your multimeter.

  1. If you measure for voltage in your home, it’s probably AC. If the measurement is on a car battery or device that runs off of DC power, it’s most likely DC itself.
  2. Make sure you are turning the selector switch to the appropriate voltage. AC has a sine wave symbol, while DC is just one solid line with another dashed under it.
  3. Insert the black probe into the COM port found on the multimeter.
  4. Great! Plug the red probe into the jack marked with a V.
  5. Make sure you are using a high voltage and turn your selector to the highest setting. Remember that there is mV in thousandths of volts, so this should be set at the lowest possible option.
  6. If you’re testing AC voltage, always wear safety gloves to avoid getting electrocuted!
  7. Power up the device you are testing by turning on your car or opening a breaker in your box.
  8. Touch the black probe to one side of the component you’re measuring and touch red on the other terminal.
  9. If you’re not getting a clear reading, turn the selector to the following highest setting until it’s at its maximum and recordable.

Multimeter Features

Be sure to remember that your multimeter has a continuity check, which can give you an idea if two items are electrically connected. 

To do this test, connect the probes on either side of your testing and turn it on. If there is a complete circuit going through from one probe to another, then your meter will beep; otherwise, it’ll stay silent!

The multimeter can do more than check the voltage and electricity flow! Some of them also test for efficiency levels by measuring diodes, capacitors, or transistors. If you’re not sure how to use those features on your particular model, be sure to consult your owner’s manual before testing anything out.

Dial Setting on Your Multimeter

Once you understand the abbreviations and settings on your multimeter, you can start to use it. First, decide whether you measure volts (V), Amps (A), or ohms (Ω). If your current is AC, switch to a V setting; if DC set yourself for A. To measure resistance, turn the dial until Ω light up green in front of whatever reading scale will be most appropriate (.001-100kohm range max.).

There’s no need to worry about which segment each corresponds with as long as they are all glowing green before moving onto measurement!

To make sure you measure an accurate voltage, set the scale a little higher than what you expect to see. For example, if your multimeter has a setting of 20 volts, the settings I would recommend putting it at 20V for this measurement.

AC Voltage Measurement Analysis

It’s often the case that voltage is less than what it should be. The good news is, you can easily use a multimeter to measure this! All you need are two probes and some extra patience when looking for their respective connections in your device (not all connectors or plugs work with each other). 

In general, any given ac power system will have an expected range of -10% up to +5%. Voltage measurements may vary depending on where they were taken, which means there could be fluctuations even within one connection point–but don’t worry, as long as the average reads between those ranges, then everything should still function properly.

About Blake Sutton

Blake has worked as an electrician for over 10 years, receiving his Journeyman Electrician license in 1998. Looking to take his professional electrical career further, in 2008 he received his Bachelor of Science in Electrical Engineering (BSEE) from the University of Texas in Austin. Blake now works full time as an electrical engineer, specializing in power systems.