How to Read Ohms on Multimeter? (Quick and Easy Guide)- Tool Nerds

A multimeter is quite a versatile tool for far more than one purpose. Most units that are available on the market today are capable of measuring resistance, voltage, and amperage of a particular circuit or component.

There are several types of multimeters, but the most widely-used ones are either analog or digital.

Thanks to the rapid development of the modern technology, a vast majority of units today are digital and quite easy to use.

However, misuse of these units can cause some serious issues. While the biggest danger lies in jeopardizing the inner components of the multimeter, fatal injuries are also a possibility, especially if one decides to neglect the safety precautions.

This guide is designed to give you a better insight into the capabilities of your unit and teach you how to utilize it properly and safely.

Anyone can use a multimeter, regardless of their previous experience with these things, but the most important thing to remember is to follow the written and unwritten rules in order to avoid unpleasant surprises.

Measuring Resistance

Resistance is the measure of electrical friction through a conductor. It is measured in Ohms and the Greek letter Omega is used as the symbol.

The first thing you should do is set your unit to the highest possible resistance range. Once you select the highest range, touch the two probes together and the display should read 0 ohms. In case you are using an analog model, the needle should go to the highest value once the probes are touching each other, and drop back to zero once separated.

Bear in mind; most analog multimeters utilize a resistance scale that moves from right to left instead of moving the other way around. It can bring some confusion in, especially if you’re not as experienced with these gadgets. Most analog units also have a knob or a switch that is responsible for calibrating the resistance to zero. Touch the probes together and adjust the knob until it points to zero ohms on the scale.

An Example

If you want to do a test reading, the easiest way to do it is to pick out a random resistor that is not a part of any circuit, set the multimeter to 20 kilo-ohms setting, and touch both ends with the probes.

The meter should output one of three values – 0, 1, or a random number that should be the actual value.

In case you get the reading of 1 (one) or OL, that means the meter is overloaded and needs a higher scale in order to output accurate results. In other words, if you see the value of 1, move the switch to a higher scale (mega-ohms).

If your unit outputs a value of 0 (zero), that means a scale that’s too high is selected. In order to fix this, try lowering the scale to ohms instead of kilo-ohms.

If you get a random value, for example, 0.5, that means you have selected the right range. In this case, the resistance of that particular component is 500 ohms or .5 kilo-ohms.

A general rule of thumb here is that it’s quite hard to find a resistor less than one ohm. That means you should repeat the process if you get lower values because there are many factors that can affect the reading such as the surrounding temperature and whether or not the resistor is a part of an existing circuit.

As we already mentioned, it’s always better to exclude the component from the circuit and conduct measures in a controlled environment without any electrical interference. In fact, you should also use an anti-static surface to measure the values as static electricity can mess up the readings occasionally.

Needless to say, if you own an auto-ranging multimeter, these steps are not required.

Other Useful Advice

There are a lot of models that don’t feature an OFF button. Now, while it seems pretty harmless and irrelevant, it’s very important that you set up the multimeter right 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.

It prevents the next person that decides to use the unit to shock it with high currents. Some meters can break if they get a sudden blast of current flowing through the inner circuit.

If you measure a component that is a part of a circuit, don’t forget to drain the capacitors before using the probes. Depending on the type of gadget you’re inspecting, the capacitors can hold a substantial amount of current, even when the circuit is dead. Therefore, there is a certain risk of injury involved even when dealing with small amounts of current.

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, there are some that are slightly different. It’s not necessarily a substantial difference, but it can yield different results on some occasions.

The Conclusion

Utilizing a meter isn’t a big deal whatsoever. Many people get reluctant when it comes to measuring current 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 when around live circuits.

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