Discover How To Read Ohms on a Multimeter (2024)

by Sean Masri | Article, Multimeter Blog

If you don’t know how to read ohms on a multimeter — you’re missing out on a highly useful function of your testing machine!

A multimeter is a versatile tool for far more than one electrical purpose. Most units are capable of measuring the resistance, voltage, continuity, frequency, and current of a particular circuit.

There are two types of multimeters — analog and digital. Thanks to the rapid development of modern technology, the vast majority of popular units today are digital and straightforward to operate.

However, misuse of these units can cause some serious issues. While the biggest danger lies in jeopardizing the inner components of your testing tool — fatal injuries are also a possibility, especially if you decide to neglect safety precautions.

Anyone can use a multimeter, regardless of their previous experience — but always follow the written and unwritten rules to avoid unpleasant surprises.

This article explains why the ohm setting on multimeter is as important for the home DIYer as the trade pro, and crucially, how to test ohms on a multimeter.

The Ohm Reading — What Is It and Why Is It Important?

Ohms and Resistance

Great! You’re reading this article to learn how to read ohms on a digital multimeter!But, so what? If you don’t know what ohms are, or for that matter, why you’re testing them, the whole exercise is pretty much a waste of time!Ohms, symbolized by the Greek letter Omega (Ω) are the units used to measure resistance. So, in the same way that frequency is stated in Hertz and current in amperes — resistance is measured in ohms.In general terms, resistance explains how easy it is for electricity to flow through a circuit. The lower the resistance, the higher the flow — and vice versa.It would be easy to assume that when testing ohms with your multimeter you want to see a high number, right? Because if a circuit isn’t allowing electricity to flow as easily as possible — it must be inefficient. But, that’s not always — or in fact, most usually — the case.Resistance is your friend, and also that of your circuit board.

The Importance of Resistance

Consider a spinning household cooling fan. When connected to the mains, 120 volts of electricity at around 15 amps flows directly into the machine. The issue is, every single component in the fan — without resistance — would be exposed to this high energy load.Resistance — and the resistors that provide them in the PCB (printed circuit board) — ensure that all the crucial components only receive the level of energy they need. Furthermore, they stop your fan from going nuclear.The speed control on the fan is, in most circ*mstances, controlled by a variable resistor. The more resistance, the slower the fan rotates — the lower resistance, the faster the fan spins. Well, up to a point. There’s a lower resistance limit, preventing your fan from blasting air through your house like a tornado — or shearing the fan blades off the unit.An ohm check can be conducted on any electrical component, machine, or circuit, to check the resistance levels and ensure they are within the limits expected. Not just protecting the internals from damage — but also guaranteeing you remain safe too.

What Are the Reasons for Using a Multimeter To Test Resistance?

Knowing how to read a multimeter ohms means you can use your testing machine to problem-solve a malfunctioning piece of electrical equipment — or ensure it is running correctly to prevent future issues.While the ohms setting on your multimeter can be utilized for a multitude of applications — the most common reasons are to:

Ensure that the circuit is functioning efficiently.
Check that correctly rated components are positioned in the circuit board.
Search for faults or malfunctioning parts.
Confirm that the electrical equipment meets safety regulations.
Troubleshoot broken or impaired electrical machinery.
Guard against internal overheating.
Check loads aren’t going to cause you physical harm.
Protect components from high-load damage.
Search for parts, wires, and components that are beginning to fail.
Measure the power consumption of the electrical machine.

Now that you understand why you want to test ohms on multimeter — it’s time to get down to business! Get your hands on your testing machine and brace yourself, as you’re about to discover how to conduct a multimeter ohm test!

How To Check Ohms on a Multimeter

The following steps explain how to test ohms with a digital multimeter — the most common and popular format of electrical tester. If you have an analog unit, the process is very similar — but refer to your manufacturer’s instructions for any particular nuances.

Testing for Ohms on a Multimeter

Make sure the machine or circuit board is disconnected from all power sources.
If your circuit includes capacitors — discharge them! Failure to do so could lead to a false reading, or cause you physical harm.
You should already know how to set your multimeter to ohms — if not check the manufacturer’s manual. Usually, it means turning the dial to the Omega (Ω) symbol.
Insert the black testing lead into the jack port marked as COM.
Insert the red testing lead into the ohm input jack port — depending on your make and model, this could be indicated by mAVΩ or just VΩ.
Switch on your multimeter.
Immediately, the LCD screen may display OLΩ — since as soon as the machine is activated, it begins to look for resistance. The OL indicates an Open Loop — that is, there is no complete circuit found, as you haven’t touched the probes onto anything yet.
Alternatively, some machines — especially auto-ranging units — may display MΩ. This means the multimeter is automatically using the highest possible scale of megaohms — as it considers the open loop to have incredibly high resistance, as it cannot detect any current flowing.
Before I get onto how to check ohms — you first need to know how to select the range (unless your multimeter is auto-ranging). In most circ*mstances, repeatedly pressing the RANGE button will cycle through the different levels.
Ideally, you should know what result you expect from the test, therefore indicating what range to use. If not, find out — otherwise, the result will mean nothing to you anyway. But, if you literally have no idea and haven’t the time to find out this information immediately, set the multimeter on the greatest range first, and test — then reduce as required. This will prevent accidental damage to your unit.
With the unit on, leads connected, and range set — it’s time to learn how to check for ohms on a multimeter. And, it’s easy!
Locate the probes on the area/component being tested. This may mean touching either end of a wire, each leg of a diode, or the endpoints of a solder pathway. It makes no difference which probe goes on either end.
Look at the result on the LCD screen. If required, and your machine has the option, press the HOLD button to retain the information.
Once you’ve finished your ohms reading, switch off your multimeter. Unplug the red testing lead and then the black. Store safely for future use.
Congratulate yourself! You now know how to test for ohms on your multimeter!

Other Useful Advice for Using an Ohms Multimeter

Switch It Off When You’ve Finished Checking Ohms!

Not just to save the internal batteries from unnecessary depletion — but also to increase safety.It prevents the next person who decides to use the unit from getting shocked with high currents — as the ohms scale range is set too low. Also, some meters can break if they get a sudden blast of current flowing through the inner circuit.Admittedly, some models don’t feature an OFF button. Now, while it seems pretty harmless and irrelevant, it’s very important that you set up the multimeter for future use. For example, if your unit doesn’t have an OFF button, put the scale on the highest value once you’re done with the measuring.

Read the Manual About How To Test for Ohms on Your Multimeter Model

Make sure you always read the included user manual, regardless of your previous experience.While a vast majority of meters work on pretty similar principles, some are slightly different. It’s not necessarily a substantial difference, but it can yield different results on some occasions.

Remove the Component Before Using an Ohms Test Multimeter

If possible, it is safe to do so, and you have the relevant knowledge — remove the component to be tested from the PCB before attaching the multimeter probes.While it remains in situ, results can be impaired by other parts of the circuits running in parallel with your target component.

Avoiding Contaminants

In addition to the above, other issues can skew your multimeter ohms test.Dirt and detritus, dust, dead insects, old solder, machine oil, or flux can all increase resistance — so ensure the area you’re testing is clean.Furthermore, make sure that when applying the test probes, your fingers or clothing do not come into contact with the metal points — as again, this can increase the electrical resistance reading.

How To Read Ohms Conclusion

You now have a full understanding of ohm readings — and how to test resistance on your multimeter!

As you’ve discovered, utilizing a meter isn’t a big deal whatsoever. Many people get reluctant when it comes to measuring resistance because of the involved risks. While there is always a chance of something going wrong, one can significantly reduce the potential risks by following safety regulations and using the unit properly.

Most failures happen due to human error instead of faulty instruments. Therefore, before you start measuring different circuits, make sure that everything is set up correctly, or else you risk jeopardizing the whole process.

Needless to say, always take care of your own safety. Whether that means checking everything twice or repeating the process, it doesn’t matter, don’t lose focus, and always stay vigilant around live circuits.

If you can, always have a partner by your side if you’re dealing with high voltages so they can react promptly and accordingly if something goes wrong. Pay attention to the CAT rating on your meter and make sure you’re using a suitable device for the occasion.

I hope you enjoyed this guide and found the information useful! If you have a friend you believe would benefit from learning how to read ohms on a multimeter — please feel free to share!

How To Read an Ohm Meter FAQs

Q: What Does a High Ohm Reading Mean?

A high ohm reading indicates a high level of resistance. This may or may not be desirable — depending on the component in the circuit being tested.

Q: Is an Ohm Meter the Same as a Multimeter?

No. An ohmmeter can only measure electrical resistance. A multimeter can investigate other metrics, including temperature, continuity, voltage, and current.

Q: Does Higher Resistance Mean More Power?

No, it means the opposite!If the resistance is high, it means that electrical power flowing through the circuit is reduced. Equally, if there is minimal resistance, the electrical power will be higher.

Q: What Do Ohms Tell You on a Multimeter?

The ohm is a measure of resistance. On a multimeter, it indicates how much resistance there is between two parts of a circuit.

Q: Can All Multimeters Test for Ohms?

Yes! Resistance testing is a standard feature of all multimeters — along with voltage, current, continuity, and frequency.Understanding how to read ohms on a multimeter means you can troubleshoot faulty equipment, increase operational safety, and protect electrical circuits from overheating.

Greetings, electrical enthusiasts! I'm here to delve into the intricacies of reading ohms on a multimeter, a topic that holds paramount importance for both DIYers and trade professionals. My expertise stems from hands-on experience in electrical engineering and testing, coupled with a profound understanding of the principles behind multimeters.

In the realm of electrical diagnostics, a multimeter is a Swiss army knife, capable of measuring resistance, voltage, continuity, frequency, and current in a circuit. In this discussion, we'll primarily focus on the ohm setting of a multimeter, shedding light on its significance and how to effectively utilize it.

Ohms, symbolized by the Greek letter Omega (Ω), serve as the units for measuring resistance. Understanding resistance is crucial, as it dictates how easily electricity flows through a circuit. A lower resistance facilitates higher current flow, while higher resistance impedes it. Contrary to intuition, a high resistance reading isn't always undesirable; in many cases, it's a protective measure for the circuit.

Consider a household cooling fan as an example. The resistors on the printed circuit board (PCB) of the fan introduce resistance, preventing every component from being exposed to the full energy load. Resistance ensures controlled energy distribution and prevents catastrophic failures, such as the fan blades shearing off due to excessive speed.

Now, why should you bother testing ohms on a multimeter? The applications are diverse and critical:

Ensure efficient circuit function.
Confirm the presence of correctly rated components.
Identify faults or malfunctioning parts.
Verify compliance with safety regulations.
Troubleshoot electrical machinery.
Guard against internal overheating.
Prevent physical harm from high-load conditions.
Protect components from damage.
Identify failing parts, wires, or components.
Measure power consumption.

Moving on to the practical aspect, here's a concise guide on how to check ohms on a digital multimeter:

Disconnect the circuit from power sources.
Discharge capacitors if present to avoid false readings.
Set the multimeter to the ohm symbol (Ω).
Insert the black lead into the COM port and the red lead into the ohm port.
Switch on the multimeter and select the appropriate range.
Touch the probes to the component being tested.
Read the result on the LCD screen.
Optionally, use the HOLD button to retain information.
Turn off the multimeter and disconnect the leads.

A couple of additional tips for using an ohms multimeter:

Always turn off the multimeter when done to save batteries and enhance safety.
Read the manual for your specific multimeter model to understand any unique features.
If possible, remove the component from the circuit for accurate readings.
Keep the testing area clean to avoid contaminants affecting readings.
Be mindful of safety precautions, including having a partner for high-voltage tasks.

In conclusion, mastering the art of reading ohms on a multimeter empowers you to troubleshoot, enhance safety, and safeguard electrical circuits. I trust you found this information insightful, and if you have fellow enthusiasts eager to learn, feel free to share this knowledge!