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Brand: Extech
Extech MA445 400 A True RMS AC/DC Clamp Meter with NCV
Description
MA445 is the top model of the Extech MA440 series 400 A clamp meters. It measures true RMS AC and DC current to 400 A through a 30 mm Hall-effect jaw, true RMS AC and DC voltage to 600 V, resistance, capacitance, frequency, duty cycle and Type K temperature, and has a built-in non-contact voltage (NCV) detector and flashlight.
An 11-function clamp meter for electricians and plant technicians
The MA440 series has three versions: MA440 for AC current, MA443 with true RMS AC current and Type K temperature, and MA445 which adds DC current. The MA445 therefore covers automotive, solar and control-circuit DC current checks as well as normal AC loads, and has a DC Zero function to null residual magnetism before a DC measurement.
The jaw opening of 30 mm (1.2 in) fits conductors up to 500 MCM. A built-in non-contact voltage detector for 100 to 600 V, a bright flashlight, a large backlit display and relative mode for capacitance make it a general-purpose tool for fault finding in distribution boards and motor starters.
Features stated in the datasheet and manual
- 11 functions on the MA445 as listed in the datasheet; true RMS AC current and voltage with crest factor allowances stated in the manual.
- Frequency response 40 to 400 Hz on MA445 (50 to 60 Hz on MA440 and MA443).
- Data hold, max/min, auto power off that can be disabled, low battery indication.
- Complete with test leads, three AAA batteries and pouch, plus a general purpose Type K temperature probe.
Technical specification
Measurement specification (manual, MA445 column)
| Parameter | Specification |
|---|---|
| AC current | 40.00 A and 400.0 A ranges; ± (2.5 % + 5 digits); 40 to 400 Hz; true RMS |
| DC current | 40.00 A and 400.0 A ranges; ± (2.0 % + 3 digits); ZERO function |
| AC voltage | 4.000 V to 600 V; ± (1.2 % + 5 digits) on lower ranges, ± (1.5 % + 5 digits) at 600 V |
| DC voltage | 400.0 mV to 600 V; ± (0.8 % + 1 digit) to ± (1.0 % + 3 digits) |
| Resistance | 400.0 ohm to 40.00 Mohm; ± (1.0 % + 2 digits) to ± (2.0 % + 5 digits) |
| Capacitance | 40.00 nF to 40.00 mF; ± (4.0 % + 5 digits) on mid ranges |
| Frequency and duty cycle | Frequency 0.01 Hz to 1 kHz band in the manual (datasheet 1 MHz); duty cycle 0.1 to 99.9 % |
| Temperature (Type K) | -40 to 1000 C (-40 to 1832 F) meter range; accuracy excludes the probe |
| Non-contact voltage | 100 V rms and above, within about 10 mm; LED, beeper and NCV lamp |
General specification
| Parameter | Specification |
|---|---|
| Display | 4000-count multi-function backlit LCD; 3 updates per second |
| Clamp sensor | Hall effect (MA443 and MA445); extra error of 1.0 % if the conductor is off-centre |
| Jaw opening | 30 mm (1.2 in) |
| Maximum voltage | 600 V AC/DC to any terminal; CAT III 600 V; pollution degree 2 |
| Auto power off | 15 minutes (MA443 and MA445) |
| Operating conditions | 0 to 30 C at up to 80 % RH, derated to 45 % RH at 40 to 50 C; altitude up to 2000 m |
| Power supply | Three 1.5 V AAA alkaline batteries |
| Dimensions and weight | 228 x 77 x 41 mm (9 x 3 x 1.6 in); 265 g with batteries; drop protection about 1 m |
| Safety standards | EN61010-1, EN61010-2-032, EN61010-2-033; UL 61010 and CSA listings per manual; indoor use only |
Order codes and variants
The datasheet lists MA440 (400 A AC clamp meter), MA443 (true RMS 400 A AC clamp meter) and MA445 (true RMS 400 A AC/DC clamp meter), each also available as an N version with optional NIST-traceable calibration by adding -NIST to the part number.
Note that the datasheet and manual differ in some secondary ranges, for example frequency and capacitance upper limits; the manual values are listed above and the datasheet figures should be treated as headline values.
Operating and safety notes from the manual
Check the meter and leads for damage before use, never exceed 600 V, and keep fingers behind the barrier on the clamp. Centre the conductor in the jaw, because an off-centre position adds 1.0 % error. Use the ZERO function on DC current to null the display before clamping the conductor.
Keep the meter away from strong electromagnetic fields, which can give unstable readings. The supplied Type K probe does not cover the full temperature range of the meter.
Typical uses in Gulf maintenance work
General engineering note: AC/DC clamp meters are used for compressor and motor load checks, DC checks on battery chargers and UPS strings, solar combiner boxes, vehicle and generator charging circuits, and tracing control circuits. NCV is for pre-checks only and must not replace proving a circuit dead with a rated tester.
Related Extech items
For logging a three-phase feeder see the PQ3450 power analyzer; for insulation tests, the MG500. More choices are in the portable test and measurement category.
Field use note
Use the meter only within its stated safety category, and check the test leads and jaw before each use. Store it in its case and arrange calibration at regular intervals.
Frequently asked questions
What is the difference between MA440, MA443 and MA445?
MA440 is a 400 A AC clamp meter, MA443 adds true RMS and Type K temperature, and MA445 adds DC current with a DC zero function.
What is the maximum voltage rating?
600 V AC/DC maximum to any terminal and CAT III 600 V according to the manual.
What jaw size does it have?
A 30 mm (1.2 in) jaw opening that fits conductors up to 500 MCM.
Does it include a temperature probe?
Yes. The MA443 and MA445 include a general purpose Type K probe, which does not cover the meter full range.
Does Seven Star LLC act as an Extech distributor?
No. Seven Star LLC is not an Extech distributor; it is an independent Muscat-based supplier that quotes Extech products on request.
Documents and quotation
The official Extech datasheet and user manual for MA445 are hosted on this page for download. Seven Star LLC is an independent supplier in Muscat; send your quantity and delivery location through the quotation form and we will quote this item. Please confirm the exact order code, supply voltage and output options against the documents before ordering. More related products: product category.
Datasheets & Documents
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About brand
Extech Instruments is an American brand of handheld test and measurement instruments, founded in the early 1970s in Waltham, Massachusetts. FLIR Systems acquired Extech in 2007 for about $40 million, and FLIR itself became part of Teledyne in 2021. Extech is based in Nashua, New Hampshire, and makes meters for electrical, environmental and HVAC testing.
Extech company profile
| Founded | Early 1970s, Waltham, Massachusetts |
|---|---|
| Headquarters | Nashua, New Hampshire (since 2011) |
| Ownership | Teledyne FLIR |
| Acquired by FLIR | 2007 |
| Product families | True RMS clamp meters and multimeters, insulation testers, power analysers, IR thermometers, light meters, vibration meters, sound, humidity and air quality meters |
Milestones
- 2007: FLIR Systems acquires Extech.
- 2011: Extech moves to Nashua.
- 2021: FLIR becomes part of Teledyne.
Meters, testers and inspection tools
The Extech range includes multimeters and clamp meters, insulation and resistance testers, power analyzers, thermometers, light and sound level meters, anemometers, tachometers, vibration meters, moisture meters, borescopes and water quality meters. Each datasheet and user manual lists ranges, accuracy, safety category and ordering codes, and many models are listed with NIST-traceable calibration versions ordered by adding -NIST to the part number.
Supply through Seven Star LLC
Seven Star LLC is an independent supplier in Muscat that quotes Extech products for projects in Oman and the GCC, with the official Extech datasheet and user manual attached to each product page.
Extech products we list
Facts checked against FLIR's 2007 announcement and published Extech histories, October 2026.
Related products
Frequently Asked Questions
What is the difference between MA440, MA443 and MA445?
MA440 is a 400 A AC clamp meter, MA443 adds true RMS and Type K temperature, and MA445 adds DC current with a DC zero function.
What is the maximum voltage rating?
600 V AC/DC maximum to any terminal and CAT III 600 V according to the manual.
What jaw size does it have?
A 30 mm (1.2 in) jaw opening that fits conductors up to 500 MCM.
Does it include a temperature probe?
Yes. The MA443 and MA445 include a general purpose Type K probe, which does not cover the meter full range.
Does Seven Star LLC act as an Extech distributor?
No. Seven Star LLC is not an Extech distributor; it is an independent Muscat-based supplier that quotes Extech products on request.
Reviews
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