Keysight U1242C True RMS Handheld Digital Multimeter

Key Features At A Glance

• 10,000-count display with up to 0.09% basic DC voltage accuracy
• 10,000-count display with analog bar graph and dual-display readout
• CAT III 1000 V / CAT IV 600 V overvoltage protection
• U1240C Series certified to IP 67 and tested to withstand a 3-meter (10-foot) drop
• Up to 400 hours of battery life on the U1240C Series
• Infrared (IR)-USB connectivity standard; optional IR-to-Bluetooth adapter for wireless remote logging
• U1242C adds harmonic ratio, ZLOW low-impedance mode, Vsense non-contact detection, and T1–T2 differential temperature
• Built-in LED flashlight on the U1240C Series for working in poorly lit environments
• Functions include DC/AC voltage and current, resistance, capacitance, frequency, temperature, continuity, and diode test

The Keysight U1240 Series comprises the U1240B and U1240C families of handheld digital multimeters built for technicians and industrial test engineers who need to keep a production line running and prevent unplanned shutdowns, whether on the bench or in the field. The U1240C Series is housed in a rugged overmolded enclosure, certified to IP 67 for dust and water resistance, designed to absorb a 3-meter (10-foot) drop, and rated for up to 400 hours of battery life so it can keep working through long installation and maintenance jobs.

The series supports the measurement tasks the instrument is built for: reading the harmonic ratio of incoming AC voltage to gauge distortion from switched-mode loads before deciding whether deeper analysis with an oscilloscope or spectrum analyzer is warranted, reducing false readings from stray voltages in non-energized wiring with the low-impedance ZLOW mode, and non-contact detection of live AC wires through Vsense. In HVAC installation, maintenance, and troubleshooting, the dual and differential temperature capability lets a single instrument read both source and ambient temperatures simultaneously — for example comparing warm return air against cool supply air to reveal evaporator cooling behavior over time.

The series is suited to work in harsh working environments and supports HVAC installation, maintenance, and troubleshooting — for example, measuring boiler and air temperature simultaneously to verify safety requirements, or viewing the temperature difference between warm return air and cool supply air to reveal an evaporator's cooling behavior. The harmonic ratio function helps detect distortion in incoming AC voltage that can overheat motors, generators, and transformers or cause premature breaker tripping and blown fuses, helping decide whether further analysis with an oscilloscope or spectrum analyzer is warranted.

ValueTronics stocks and holds its own inventory in a 20,000-square-foot secure warehouse at 1675 Cambridge Drive in Elgin, Illinois.

Brand Heritage

Keysight Technologies traces its measurement heritage to Hewlett-Packard, whose test and measurement business was spun off as Agilent Technologies in 1999 and then established as Keysight Technologies in 2014.

Compare Other Models in This Series

The U1240 Series is organized into two families: the U1240B Series and the U1240C Series. Within each family, the model variants share a common 10,000-count measurement platform while differing in the set of special functions and, in the U1240C generation, the rugged and connectivity features that surround that core.

The U1240C Series comparison covers the U1241C and U1242C, both offering 10,000-count resolution, true-RMS AC, auto and manual ranging, and the same DC voltage, AC voltage, current, resistance, frequency, capacitance, and temperature measurement set, with the U1242C extending the platform with additional special-purpose functions.

Each new model below is its own dedicated product page with condition-matched pricing. Select the specific U1240 Series model that matches your required functions and measurement ranges, and review that model's own specification table for the exact values that apply to it.

The U1242C is distinguished within the U1240C Series by its special-feature set: harmonic ratio measurement, the ZLOW low-impedance mode, Vsense non-contact voltage detection, and T1–T2 differential temperature measurement — functions listed for the U1242C only in the series comparison. The U1242C also provides a 100 Ω resistance range where the U1241C begins at 1000 Ω.

Within the U1240C Series, the U1241C and U1242C share display resolution, accuracy, and the core measurement ranges shown in the comparison table; the differences are concentrated in the special features — harmonic ratio, Vsense, ZLOW, and T1–T2 differential temperature are listed for the U1242C only — and in the resistance range starting point. Consult the comparison table for the per-model entries.

Between generations, the IP 67 certification, 3-meter drop rating, up to 400 hours of battery life, and built-in flashlight are specified for the U1240C Series, while the U1240B Series connects to the IR-to-USB cable or IR-to-Bluetooth adapter through the U1179A IR connectivity bracket. Model-specific accuracy and range figures for each variant appear in its own specification table.

Additional differences in specifications beyond the few shown above are not listed here — see each model's full specifications below.

Accessories Supplied

• 4 x 1.5 V AAA batteries (included)

Product Core & Specifications

Important: Do not allow the temperature sensor to contact a surface that is energized above 30 Vrms or 60 V DC. Such voltages pose a shock hazard.

Important: After a ZLOW voltage measurement (U1242C), wait at least 20 minutes to cool down thermal impact before making the next measurement.

Important: Current can be measured up to 440 mA continuously (maximum 20 hours for current above 440 mA and up to 600 mA); after measuring 100 mA cool down at least 6 seconds and after 600 mA at least 3 minutes, or use the NULL function to zero out thermal effect.

Important: On the 10 A range, current can be measured up to 10 A continuously; for current above 10 A up to 20 A (maximum 30 seconds) add 0.3% to specified accuracy, then cool the meter for twice the measured duration before lower-current measurements.

Important: The U1240B Series additionally requires the U1179A IR connectivity bracket to use the IR-to-USB cable or IR-to-Bluetooth adapter for PC connectivity.

About this New unit

This is a brand-new, factory-sealed unit, supplied exactly as it arrives from the manufacturer and backed by the full manufacturer warranty. For the exact configuration, available options, included accessories, or current lead time for your application, our Test Architects can confirm the details before you order.

ValueTronics supplies both new and used test and measurement equipment. New units ship factory-sealed, exactly as received from the manufacturer; every used unit is inspected and functionally verified in-house at our 20,000 sq ft secure facility in Elgin, Illinois before it ships. Our Test Architects can help you select the condition, calibration, and configuration that fit your application.

Please review the Manufacturer's Data Sheet to verify published specifications. Feedback on this webpage is always welcome — please reach out to your Test Architect at any time for questions or concerns. Thank you, we truly appreciate you being our customer.