The digital multimeter could be described as the Swiss Army Knife of electrical testing equipment. Below, some experts explain why this testing tool is so important for electricians.

Is the multimeter one of an electrician’s most useful testing tools?

John Olobri, technical training consultant for AEMC, Dover, N.H.: The multimeter provides many useful functions for electricians. Top of the list are voltage, current and continuity measurements.

Michael Crepps, product application specialist for Fluke Corp., Everett, Wash: Yes, multimeters are the standard tool to get the job done. Electricians are using multimeters for troubleshooting, verification or solving problems in the residential, commercial and industrial fields. It is the versatility and the ability to be used in multiple applications that multimeters give you what you need, and you should expect accurate, reliable and safe measurements.

Amy Hart, senior product manager at Klein Tools, Lincolnshire, Ill.: They are versatile and have lots of test functions and options.

Jeff Jowett, senior applications engineer for Megger, Dallas: Absolutely. A handheld tool that’s easy to carry and transport, rugged for demanding job sites, and with a multiplicity of functions that would otherwise fill a toolbox with separate instruments. With the many models available, it’s possible to select a tool that specifically fits a particular job application. And it will be small, easy to transport and operate, and relatively inexpensive.

Megger DPM1000 power clamp meter
us.megger.com

Robert Milner, director of global business development at Teledyne Flir, Wilsonville, Ore.: Absolutely. Most electricians own a multimeter, as it is a critical tool for testing and troubleshooting electrical circuits. Multimeters are used to measure various electrical properties like voltage, current and resistance, which are essential for diagnosing problems and verifying proper operation of electrical systems. In addition to electricians, multimeters are also used by other professionals, such as electrical engineers, electronics technicians and hobbyists.

What functions should buyers expect from today’s multimeter models?

Olobri: Most good multimeters today provide many more functions than their predecessors.

Crepps: Not a function, but category safety ratings are something that should not be overlooked and should be expected when shopping for a new multimeter. Knowing the environment and having a proper work [situation]. On more of the basics side, a DMM—it has the ability to measure voltage (AC/DC), current (AC/DC), resistance and continuity. Another function would be the min/max feature, the ability to capture and hold measurements like voltage dips or to monitor current on a motor, essentially turning a DMM into a recorder for as long as the function is engaged. Also, a multimeter with an auto-volt function, when taking a voltage measurement on an electrical system, the meter will sense if the signal is either AC or DC. This function is a one-stop selection on the dial/knob that could potentially eliminate any mishaps when you might not realize what function is on.

Hart: AC or DC voltage, and measure appropriately.

Klein MM450 multimeter
www.kleintools.com

Jowett: Traditionally, a multimeter implied the three basics: volts, amps and ohms. Such meters are still available and are sold principally on price and simplicity of operation. But an absolute plethora of new and highly developed functions have been added in recent years. True RMS measurement has become a requirement in some sophisticated operations like UPS, inverters and motor drive systems. Duty cycle is a useful function for pulse trains.

Capacitance, frequency and open circuit voltage for diode tests are three functions useful in advanced testing. Min/max and peak are vital for troubleshooting. Don’t overlook data hold for testing in darkened environments where mistaken readings are a hazard.

Milner: While there are many types of multimeters, all should share some common functions and features that are essential to their operation such as measurement of voltage, current and resistance. Other features, such as a low pass filter, data hold, relative and min/max/average data display, have become industry standards.

How have true multimeters and DMMs changed in the last two years?

Olobri: Good multimeters today have accuracies up to 100,000 counts, where typical multimeters from years past were either 4,000 or 6,000 counts. From a safety perspective, good multimeters are rated at 1,000V CAT III or even 1,000V CAT IV. Many are packaged in shockproof housings and are somewhat water-resistant.

Crepps: Due to IEC61010 and the continual updates to safety and manufacturing standards, there have been recent changes to increase safety, specifically by increasing the protective shrouding on the banana jack input to the digital multimeter. This limits the potential risk of accidental shock.

Fluke 87V Digital Multimeter with i400 clamp accessory 
www.fluke.com

Hart: Addition of lead alert to help know where to place leads and avoid blowing fuses, back-lit displays and TRMS.

Jowett: DMMs now offer a fairly high display count, which improves accuracy. Better materials and case molding techniques, including protective rubber boots, along with microcircuitry, have made DMMs more rugged so that the inevitable dropping need not take the unit out of service. Automated shutters on terminals now prevent leads from being incorrectly inserted on the wrong terminals, which in worst case could facilitate arc flash/blast. A superb safety feature.

Milner: Thermal cameras—some premium multimeters now incorporate a thermal camera to guide the user to problematic issues such as loose connections or overheating components. 

Many meters can also plug in a thermocouple for contact temperature readings.

Below are some other helpful features:

• Work lights: Multimeters now often have LED work lights built in to better see and speed up what you are doing around potentially dangerous electrical equipment.
• Improved filtering: Data filtering features such as LoZ (eliminates ghost-voltages) and VFD (for variable-frequency drives) provide users with better data for the most accurate diagnosis of problems.
• Connectivity: Many modern multimeters now include Bluetooth or Wi-Fi connectivity, which allows them to be used in conjunction with smartphones, tablets or other devices. This enables users to record and share data more easily and can also provide remote monitoring and control.
• Improved Display: Multimeters are now available with larger, higher resolution displays that can show more information and make it easier to read measurements in low-light conditions.
• Enhanced measurement capabilities and accessories: Modern multimeters can measure more electrical properties than ever before, including frequency, capacitance and temperature. Flexible current probe accessories allow users to take measurements in tight or awkward spots. Some meters have built in noncontact voltage detectors.
• Data logging: Some multimeters also include features like data logging, which can be used to track changes in electrical properties over time. Some meters can also display data graphs to aid in decision-making.
• Durability: Multimeters with improved resistance to impact from dropping and moisture intrusion are now common. These ruggedized meters are better suited for use in demanding environments like construction sites, industrial settings and other harsh conditions.

With many types of test meters offering more functions, is the need for multimeters declining?

Olobri: One type of meter typically used by electricians that is different than a multimeter is an insulation tester. This type of device injects a high voltage at low currents to look for deficiencies in the insulation.

Crepps: No. With test meters and multimeters, having more functionality means an increase in versatility to perform more jobs with one meter. Having a DMM that can measure temperature or have the capability to use current clamps (for higher current measurements) will limit the number of meters that they have to cycle through when performing troubleshooting or workflow out in the field.

Hart: No, multimeters remain a versatile tool that are useful in a variety of applications.

Jowett: No. For one thing, with the many models available on the market and the many functions now offered, it is often possible to tailor multimeter selection to exactly the tests that need to be performed and no more, no less. Electricians, maintenance people, engineers, etc., may find themselves working exclusively within narrow testing parameters—home automation systems, surveillance systems, security, alarm and control systems to cite just a few.

Milner: The need for multimeters is not decreasing, but is increasing due to the widespread adoption of modern technologies such as renewable energy systems, electric vehicles and smart home devices.

Flir DM285 digital multimeter
www.flir.com

When is a multimeter not the best choice?

Olobri: There are a small percentage of analog multimeters available. A typical use of an analog multimeter is to watch the needle movement. As measurements occur, when the meter movement stops is a good indication that the reading is stable.

Crepps: Using an I/V curve tracer, specifically designed to verify PV system performance would be a better suited tester because it adds more functionality than just the basic measurements. An I/V curve tracer will validate the overall performance of the panel by measuring the irradiance into the panel, where a technician can then establish a voltage and current curve to verify that the solar panel is performing within manufacturers specs.

Hart: Yes, but it’s not very common anymore.

Jowett: Yes, niche applications remain. Smooth pointer travel is desirable for dynamic tests where not just the measurement but the change over time is paramount, as dancing digits are difficult for the human brain to process. Also, in an environment of ghost voltages, the high input impedances of DMMs can cause interference with the correct readings while the low input impedances of analogs allow coherent pointer travel. Radar and radio operations also tend to require smooth pointer travel for dynamic measurements. And there are also those who merely prefer the aesthetics of pointer travel and will continue to support a lesser market.

Milner: Examples include clamp meters, circuit tracers, insulation testers, power quality analyzers and cable testers. In these situations, professionals should consider owning one of these usage-specific test tools.

Header image: AEMC Digital Multimeter MTX 3292B www.aemc.com