Multimeters: All You Need to Know

As an Amazon Associate Conductscience Inc earns revenue from qualifying purchases

Multimeters: Introduction

Multimeters or multitesters are versatile electrical tools utilized by engineers and electronic technicians to test and troubleshoot household wiring, batteries, electric motors, power supplies, HVAC systems, and other equipment. Note that multimeters act as ammeters, voltmeters, and ohmmeters with high resolution of milliunits; therefore, they are also known as volt-ohm-milliammeters (VOMs). Additionally, multimeters have different functionalities, and specialized features, such as diode testing and true root mean square (RMS) capabilities.

Interestingly, multimeters were invented in the 1920s as radio receivers and were initially called Avometers – an invention credited to the British engineer Donald Macadie. Now there are three main types of multimeters: analog units that have moving pointers, digital models with easy to read displays, and Fluke meters. Note that Fluke meters, firstly introduced in 1977, can be more costly than other products as they have sophisticated functions and are protected against transient voltage and damage.

Multimeters | Basic Concepts

• Ammeters: Ammeters measure the current or the flow of electric charge. Current can be of two types: alternating (AC) and direct (DC). In AC, the current changes polarity and causes dynamic changing magnetic fields; while in DC, the current flows in a fixed direction and has a constant magnetic field. Note that current electricity is different than static electricity in which all elements are made of electric charges (e.g., rubbing of certain materials against each other).
• Voltmeters: Voltmeters measure voltage or the electrical potential difference in the electric charge between two points. Voltage, sometimes called electromotive force, is what makes electric charges to move continuously. This power, measured in volts (V), can be triggered by generators, batteries, and others.
• Ohmmeters: Ohmmeters measure resistance or the material’s tendency to impede the flow of current. Bigger resistance translates into a reduced flow of electricity. Resistance of one Ohm means that a conductor allows a current of one ampere (A) to flow with a voltage of one volt.

Choosing a Multimeter: Factors to Consider

Given the wide applications of multimeters across different commercial, industrial, and household settings, it’s no surprise that multimeters are in-demand products. Prospective buyers should consider three major factors:

• Requirements
• Specifications
• Total costs

Requirements: Depending on the type of work, users can choose between benchtop and handheld models. Note that although benchtop models provide some superior methods for reading resistance and other parameters, modern handheld models are equally powerful and convenient, especially for field measurements. Another decision users should make is between analog and digital models. Note that although digital models might take some time to stabilize, they are highly accurate and easy to read, which makes them preferred units among specialists and do-it-yourself enthusiasts. Furthermore, users should look for units with good response times. If the response time is slow, measurements can become confusing.

Specifications: Accuracy, precision, resolution, and range are all essential specifications to consider. For example, accuracy is a vital factor to look for when choosing a multimeter, which usually requires a comparison to an industry standard. We should mention that some applications, such as automotive, medical, or other specialized settings, require higher accuracy (0.025%, 0.5%, etc.), with regular calibration being essential in achieving accurate readings. When it comes to the resolution capabilities of any digital unit (or the smallest change a tool can detect), we should mention that multimeters can employ counts or digits; higher counts and digits provide higher resolution. Some brands like Fluke, for instance, produce 3 ½ multimeters with counts of up to 6,000, as well as 4 ½ units with counts of 20,000 or 50,000. Last but not least, safety categories (e.g., CAT III) are fundamental factors to guarantee long and secure use.

Total costs: Depending on the design, size, specialized parameters, brand popularity, and safety ratings, costs can vary significantly. Note that although multimeters are designed to measure current, voltage, and resistance, some units have additional measuring capabilities, such as capacitance, continuity, diode testing, input resistance, true RMS, auto-hold functions, auto-ranging, and long battery life (of above 1,000 hours). Other additional features may include low pass filter, low impedance mode to prevent ghost and induced voltages during readings, data logging for better documentation, USB interface, and a graphic display for real-time measurements. As mentioned above, some high-quality products and Fluke multimeters are most costly than meters for general applications. Lastly, accessories, such as probes and neck lanyards, can add to the final cost of a unit.

Best Multimeters for Sale

Having the right combination of tools can facilitate readings and troubleshooting, so having one instrument that combines the different measurement functions of single-task meters is essential in a variety of settings, such as environmental applications, true RMS AC current measurements, DC average measurements, industrial settings, commercial systems, and home use. With a variety of units and brands on the market, however, choosing a multimeter can be a challenging task. Based on different specifications and user reviews, here are the best multimeters for sale.

1. Fluke 116 HVAC Multimeter

Fluke 116 HVAC Multimeter is a powerful 6,000-count digital multimeter ideal for HVAC applications. The unit can measure different parameters, such as resistance, continuity, frequency, diodes, and capacitance. Additionally, there’s low impedance functionality for accurate readings, as well as temperature and microamp measuring capabilities to test flame sensors. Note that the unit has a large display and LED backlight to improve usability and readability even in dim conditions. With true RMS functionality, auto-ranging functions, convenient design for one-handed operation, and CAT III 600 V safety ratings, Fluke 116 is one of the most powerful multimeters for sale.

2. Fluke 117 Multimeter

Fluke 117 Multimeter is another powerful multimeter designed for busy settings, such as educational institutions, commercial buildings, and hospitals. The unit can measure different parameters, such as resistance, continuity, capacitance, and frequency. Note that it has VoltAlert technology for non-contact voltage detection and AutoVolt automatic AC/DC voltage selection. Also, the unit provides true RMS readings regarding non-linear loads. Note that this CAT III 600 V safety rated meter has an ergonomic design and is compatible with magnetic hangers (ToolPa TM) for hands-free operation, which makes it a popular tool among specialists.

3. AstroAI Digital Multimeter

AstroAI Digital Multimeter is a versatile meter that can perform a wide range of tests for voltage, current, resistance, continuity, capacitance, and frequency. It can also test diodes and temperature. Additionally, the unit features auto-ranging and true RMS capabilities, as well as data hold and auto shut-off options. With its convenient design and overload protection (including built-in F400mA/600V and F10A/600V explosion-proof ceramic fuse tubes), this multimeter is ideal for long workdays and heavy-duty applications.

4. Innova 3320 Auto-Ranging Digital Multimeter

Innova 3320 Auto-Ranging Digital Multimeter is a great UL certified meter ideal for troubleshooting household and automotive problems (with 10 MegOhm input). The unit has a single-setting resistance function for AC/DC voltage and color-coded LEDs that make checking household batteries an easy task even for entry-level users. Besides, it comes with all the leads and holders needed for accurate use and hands-free testing, as well as protective rubber corner guards for drop protection. With its auto-ranging capabilities and different functions, this multimeter is a great choice for both professionals and do-it-yourself enthusiasts.

5. Craftsman 34-82141 Digital Multimeter

Craftsman 34-82141 Digital Multimeter is another wonderful multimeter available on the market. The unit can measure up to 600 V AC/DC and 10 A AC/DC, as well as resistance and diodes. With its large 2,000-count display, automatic shut-off function, and durable design, this meter is ideal for home maintenance, PC repair, and different applications. Note that the unit comes with a rugged case for safe and long use.

6. Tenma 72-1055 Benchtop Digital Multimeter

Tenma 72-1055 Benchtop Digital Multimeter is a powerful 1,999-count benchtop model that can measure AC/DC voltage, current, resistance, capacitance, frequency, transistor hFE, and temperature. It can also perform diode and audible continuity testing. With a backlit display and a variety of settings, this unit is ideal for different educational and commercial settings, including fieldwork. Note that the set comes with various beneficial accessories, such as test leads, alligator clips, and temperature probes, which make it highly convenient.

7. B&K Precision 5491B Multimeter

B&K Precision 5491B Multimeter is a sophisticated true RMS benchtop model. The unit can measure voltage, current, frequency, period, continuity, and diodes with a precision of 0.02%. Its dual LCD display provides two readings at once and a 50,000-count resolution. Moreover, this powerful meter features USB connectivity and RS-232 computer interface, allowing storage and remote analysis of data. Note that the unit meets the IEC safety standard 61010 and is certified for Category I of 1,000 V and Category II of 300 V, which makes it a valuable tool in a variety of applications.

8. Keithley DMM6500 6½-Digit Touchscreen Multimeter

Keithley DMM6500 6½-Digit Touchscreen Multimeter is one of the most advanced benchtop multimeters for sale. The unit is able to capture low-level signals, low resistances with impressive sensitivity, as well as transients and ultra-low sleep currents, and quiescent currents. Note that the unit’s accuracy is as follows: DC V: +/-0.0025%; AC V: +/-0.05%; DC current: +/-0.02%; AC current: +/-0.1%; Resistance: +/-0.0075%; Temperature: +/-0.7⁰C. With its touch-and-zoom capabilities and impressive connectivity, this unit ensures great readability and user comfort.

9. Cen-Tech 7-Function Digital Multimeter

Cen-Tech 7-Function Digital Multimeter is a popular multimeter that provides accurate readings for voltage, current, resistance, transistors, diodes, and batteries. We should mention that the unit has various additional functions, including a low battery indicator. One of the most tempting aspects is its affordable price, which makes it a preferred tool among beginners and do-it-yourself enthusiasts.

10. Etekcity MSR-R500 Digital Multimeter

Etekcity MSR-R500 Digital Multimeter is another affordable multimeter that can measure parameters, such as AC/DC voltage, DC current, resistance, diode, and continuity. We should note that the unit is not designed for AC current. Additionally, this meter has a data hold button and a large backlit LCD display. With a variety of settings and high safety protection, Etekcity MSR-R500 is ideal for different electrical projects.

Multimeters: Safety Tips

Before using a multimeter, users should keep in mind that working with electrical equipment requires high safety precautions. Instruments should meet different safety standards, such as the International Electrotechnical Commission (IEC) safety standards.

• To ensure that the unit is protected against electrical hazards, always consider if its range and parameters are suitable for the environment it will be used in. Familiarize yourself with the operating and safety procedures described in the user manual. Additionally, allow intervals between measurements.
• Make sure the materials used are durable. High-quality cartridge fuses, silicone rubber probes, shrouded plugs, input protections, and internal blast shields are some of the desired qualities to look for in a multimeter. For instance, a low-quality unit may melt during high current readings and cause users injuries. Always inspect for damage before using a meter and stay away from bare conductors.
• Always use gloves and avoid working with electrical systems alone. Do not forget that working with multimeters can be dangerous.

Multimeters: Conclusion

Multimeters are beneficial electrical tools employed in a variety of industrial, commercial, and home settings. As explained above, multimeters act as ammeters, voltmeters, and ohmmeters with different specialized features. Note that there are three main types of multimeters used to troubleshoot household wiring, batteries, electric motors, HVAC systems, and other equipment: analog units with moving pointers, digital models with easy to read displays, and Fluke meters.

Before choosing a multimeter, users should consider three major factors: requirements, specifications, and total costs. Accuracy, precision, resolution, and range are all essential parameters to consider. Extra measuring capabilities, such as capacitance, continuity, input resistance, true RMS, and auto-ranging functions, are also vital. That being said, one of the most important aspects to consider is safety. As working with electrical systems can be dangerous, units should meet different safety categories (e.g., CAT III) to guarantee long and secure use. In the end, as electricity is all around, multimeters are highly beneficial and in-demand instruments.