Safety Measures for Using Multimeters

Multimeters are invaluable tools across the electrical and electronic industries—but only when used safely. 

In this guide, we’ll highlight the key safety measures you should always follow when using a multimeter, broken down by the type of measurement you’re taking.

Measuring voltage

If you’ve used a digital multimeter before, you’re probably familiar with the rotary dial used to set the device’s current measurement. You can select between Voltage (‘V’), Current (‘A’), and Resistance (‘Ω’).

The Voltage and Current settings are then further divided into unique measurement positions. The curved line with a dashed line beneath represents AC, while the solid line with a dashed line beneath represents DC.

So, when using your digital multimeter to measure voltage, it’s critical to choose the correct position to avoid electric shock.

You’ll also need to pay attention to where you plug in your test leads, which are the red and black conductors with sharp probe tips. The black test lead should slot into the ‘COM’ socket on the multimeter, while the red lead should fit into the ‘VΩ’ socket when measuring voltage and resistance or the ‘A’ socket when measuring current.

Finally, note the type of voltage you’re measuring. If you’re measuring ACC voltage, make sure the probe tips do not cross over each other or touch while they’re connected to their given point on the electrical circuit—if they do, a dangerous short circuit could occur.  

Measuring resistance

Safely measuring resistance with a multimeter is much easier than measuring voltage. All you need to do is:

• Make sure the test probes are in the correct sockets—black in the ‘COM’ socket and red in the red socket marked ‘Ω’ for resistance.
• Turn the rotary switch to ‘Ω’ and touch the probes to the device you’re hoping to measure. This will display your desired reading on the digital multimeter’s screen.

For safety, keep in mind that you should only ever measure resistance on a de-energised component, or you’ll risk faulty readings. This is because multimeters use an internal battery, with the battery supplying the current flow measured by the meter.

Measuring current

Current, essentially, is the flow of electrons around a circuit. Then, the only way to measure current is to break into the circuit and ‘force’ it to pass through the device.

Before breaking the current, make sure your multimeter’s switch is set to the appropriate measurement—DC or AC ‘A’—and plug the red probe into the ‘A’ socket. You’ll then need to break the circuit and connect the multimeter’s probes to the circuit’s broken ends.

As always, make sure your device is set to the correct mode and avoid working with high-power circuits to reduce the risk of accidents.

General safety tips

Regardless of the measurement you’re currently taking, here are some general safety tips to follow:

• Do not use cracked, worn, or otherwise damaged test leads,
• Where possible, avoid handling probes with two hands, as current moving from one hand to another during an electric shock is incredibly dangerous,
• Always perform a safety check by using your multimeter to detect the presence of AC and DC voltages,
• Always wear protective gear.

Conclusion

Using a multimeter to measure voltage, current, and resistance is simple if you follow the appropriate safety procedures outlined in this guide. Stay safe!