Accidental contact with electricity constitutes roughly one-fifth of construction deaths. While a multimeter provides a certain level of protection, your safety still greatly depends on how you comply with safe work practices. If you’re new to a multimeter, it pays to observe these multimeter safety precautions.
Perform Visual Inspection
Before taking a reading, check for signs of excessive wear and tear on your handheld multimeters to know whether they will be in normal operation.
With time, the insulation material becomes more prone to cracking, whether silicone or PVC.
Thus, it makes sense to examine the unit, the two test probes, and other attachments to ensure no leaks or cracks. You should replace any broken parts before proceeding to take the measurement.
Run your fingers across the leads when you visually check its condition.
If there are burnt leads or exposing wires, replace them.
Any damages that the bare eyes can see potentially impair the future readings and pose safety threats to the user. Also, confirm that you’re not working with a faded display.
Do not assume the instrument is in proper working order.
Even though a visual check cannot give you the guarantee that the device is safe to use, it’s a critical step to prevent great electrical injuries that visible defects cause.
Check The Accuracy Of The Multimeter
Apart from a visual check, performing a functional inspection on the device’s basic features is advisable.
Before using the probes on an unknown power source, it’s wise to check their functionality on a known live circuit.
First, unplug the two probes and look for any external defects. A probe is safe to use only when it is fully covered by rubber without cracks or leaks.
Then, plug the probes back into the ports, and don’t forget to make sure the connections feel strong and secure. Finally, verify its accuracy on the known source.
It’s worth mentioning that trying to repair damaged leads is a waste of time. Any attempt to fix and use broken leads carries serious dangers to the user.
Also, conduct an ohms measurement to know whether the leads are electrically dependable.
First, set the device to the “ohms” function. Insert the two leads, then cross their tips.
If the multimeter reads 0.5 ohms or below, they are reliable leads.
See more: Do multimeters need calibration?
Multimeter Safety Precautions While Using The Meter
Here are some safety considerations when using either an analog or digital multimeter:
- The crucial step is to set up the device properly: The leads should go into the right ports, and the meter is in the right function before the reading.
- While measuring the AC voltage, never touch the probe’s tips to each other if they are still connected to the electrical circuit. The two tips that come into contact can create a ball of flame.
- Rest or hang the device since holding it in your hands means directly exposing your body to the hidden danger from transients.
- Avoid using the multimeter in damp environments under any circumstances. Also, do not measure in areas where atmospheric dangers, such as flammable vapor, are present.
- Apply the three-point test approach to avoid faulty readings: Test the probe on a known circuit before moving to the unknown equipment. Next, go back to test the known circuit. This practice will alert you if there’s any false reading before and after the measurement.
- Start with the ground clip and then the hot lead. When you finish, take out the hot lead, then the ground clip.
- Be on the lookout for any audio or visual warnings on display. These signs often show up when a dangerous voltage exists.
- Watches or jewelry are great electrical conductors. Take them off before messing with electronic circuits.
- If possible, avoid using both hands to hold the probes. Doing so will avoid personal connection to the current and reduce the possibility of a closed-circuit current running across your chest and reaching your heart.
- Do not change settings while the probe tips are still in contact with the circuit.
Safety equipment is crucial to minimize the risk of electrical contact while using a multimeter.
It’s a must when you’re working with any circuit beyond 50 V.
To safeguard yourself from live circuits, use protective equipment:
- Put on insulated gloves
- Stand on an insulated mat to protect yourself from a direct electric shock throughout the body
- Wear flame-resistant clothes
- Put on a face shield and safety glasses
Besides safety devices, having a partner by your side while taking the measurement is helpful when an electric shock occurs.
An accident could accelerate to a life-threatening situation if there’s no one around to provide immediate help.
CAT And IP Ratings
CAT rating or CAT category rating is the first thing you should determine while choosing a multimeter.
This specification tells you where the electrical supply chain the probes can be safely used. CAT ratings fall into four categories: CAT I, CAT II, CAT III, and CAT IV.
The rating number typically positions near the input jacks of the electricity meters.
Remember to check whether the unit has a proper category rating before using it.
The closer the operator is to the power source, the greater the potential threats from transient impulse.
It means you will need an analog or digital meter of a higher category for better transient protection.
In other words, a higher CAT rating can deal with electrical systems with greater power and transients.
That is to say: a unit rated CAT III is more resistant to higher transients than the one with a CAT II rating. Using a correct meter will shield you from fatal burn injuries.
If the concept of categories appears confusing to you, the best practice is to err on the side of precaution and select a multimeter with the highest category possible.
A 480 V piece of electrical equipment requires at least a CAT III-600 V meter. Yet, a CAT III-1000 V multimeter still works just fine in this circumstance.
Two-digit codes define how the multimeter can hold up to water and dust damage. It shows the size of dust particles that the instrument can tackle and the depth of water it can go under without malfunctioning.
Ingress protection levels for dust particles (the first digit) run from 0 to 6.
The 0 gives no protection for the multimeter, while the number 5 sufficiently keeps dust from interfering with the unit’s performance. The 6 IP number is completely dust-proof.
The second digit indicates the ingress protection levels against water damage and ranges from 0 to 8.
7 rating means the device can dive as deep as 1 meter, stay there for 30 minutes, and stay intact and functional afterward. The 8 rating allows the instrument to be submerged beyond 1 meter.
Store the multimeter in a dry, safe place without the potential risk of damage or impact.
A multimeter commonly arrives with a storage case that keeps all the attachments in one place and protects delicate components from physical damage.
When you’re not going to use the instrument for an extended period, keep in mind to take out the batteries from the case to prevent them from draining and corrosion at the connections from happening.
This action would extend the battery life.
If the leads are tightly intertwined for a long time, some internal breaks are likely to happen. These parts require extra care from the user.
Using either analog or digital multimeters undoubtedly carries dangers, but everyone can operate it safely with multimeter safety precautions and safety equipment.
Always keep an eye for external defects first before using the precision instrument.
Finally, if you are still shopping for a multimeter, pick a unit rated for the highest category as it provides a proper category rating for a wider range of electronic equipment.
Further reading: Is it safe to stick a multimeter in an outlet and why?