The Extech MA440 Series is a family of three 400A clamp meters built around a 1.2 inch (30 mm) jaw that fits conductors up to 500 MCM. The series gives buyers a choice between three configurations: the MA440 with 9 functions including AC Current, the MA443 with 10 functions adding True RMS measurement and Type K Temperature, and the MA445 with 11 functions adding AC/DC Current measurement with a DC Zero function. All three models share a common platform with a built-in Non-Contact Voltage detector, multimeter functions, and a large backlit LCD display.

These clamp meters are designed for electrical maintenance and troubleshooting work where non-invasive current measurement is needed. The True RMS models (MA443 and MA445) are intended for accurate readings of non-sinusoidal waveforms, while the MA445 specifically extends to DC current measurement for automotive and DC system applications. The Type K Temperature input on the MA443 and MA445 supports applications requiring temperature measurements alongside electrical readings. The built-in NCV detector covers 100 to 600V for quick voltage-presence checks before contact testing.

Each new MA440 Series clamp meter from ValueTronics is sourced, inspected, and shipped from our 20,000 square foot warehouse at 1675 Cambridge Drive, Elgin, Illinois. Unlike pass-through brokers and drop-shippers, we hold the physical inventory, our team handles each unit directly, and you have a real point of contact for questions about the meter, accessories, or NIST calibration options before and after the order ships.

Brand Heritage

Extech Instruments was acquired by FLIR Systems in 2007 and operates as part of the FLIR Commercial Systems group. FLIR Systems was subsequently acquired by Teledyne Technologies in 2021, and the Extech brand continues under Teledyne FLIR.

Compare Other Models in This Series

The MA440 Series organizes around three models that share the same 400A clamp body, the same 1.2 inch jaw, the same NCV detector, and the same core multimeter functions — but differ in current measurement capability, True RMS support, and Type K temperature input. The MA440 is the AC-only baseline model with 9 functions; the MA443 adds True RMS and Type K Temperature for 10 functions; the MA445 adds AC/DC Current measurement for 11 functions.

The selection logic across the family is driven by three questions: does the application include non-sinusoidal waveforms (variable frequency drives, switching supplies, LED loads) that require True RMS for accurate readings, does the application include DC current measurement (automotive, solar, DC drives, battery systems), and does the application require Type K temperature measurement alongside electrical readings.

Each new MA440 Series model below is listed on its own product page with condition-matched pricing. Select the model that fits your current measurement and budget profile.

The MA440 is the AC-only model with average-responding current measurement at ±2.0% AC basic accuracy and 100 µF capacitance range. It is the baseline configuration for general electrical work on standard sinusoidal AC loads. The MA443 steps up to True RMS measurement at ±1.8% AC basic accuracy, expands capacitance range to 40 mF, and adds Type K temperature input, Max/Min capture, and a built-in flashlight.

The MA445 sits at the top of the family with True RMS AC measurement plus DC current measurement to 400A — a capability that is required for solar PV, EV charging systems, battery systems, and DC drive applications where the lower-tier MA440 and MA443 cannot read accurately. Current accuracy on the MA445 is ±2.5% AC and ±2.0% DC. Like the MA443, the MA445 includes Type K temperature input, Max/Min capture, and the built-in flashlight, and it adds a DC Zero function for accurate DC current measurement. See the comparison table that follows for the full per-model specification breakdown.

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

Accessories Supplied

• Test leads
• Three AAA batteries
• Pouch
• General purpose Type K Temperature probe

Product Core & Specifications

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.