Extech MA445 Clamp Meter Review

Editor Rating: 4.6/5

Great Product

Extech Clamp Meter Review

Reviewed by: Timothy Henderson

Last modified: May 27, 2023 @ 1:31 pm

  • Design
  • Functionality
  • Price

Extech MA445 Clamp Meter Review Summary

With fuss-free operation, no fancy frills, yet offering formidable flexibility — the Extech MA445 Clamp Meter is an excellent budget unit for the keen amateur and light-project pro.

Boasting TRMS tech, this machine delivers seriously precise results — whether you’re checking frequency, current, voltage, resistance, or continuance. And, with a reassuring non-contact voltage detector — you’re shielded against the risks of unforeseen live wires.

A backlit LCD screen ensures effortless operation in challenging light environments, while an in-built flashlight delivers welcome illumination onto your target circuitry. Furthermore, with a CAT III rating, this machine is compatible with industrial-grade three-phase systems.

I suggest that HVAC repairers and automotive enthusiasts will welcome the temperature testing facility — delivering heat readings from -40 to 1832 degrees Fahrenheit. And, with a low-battery warning light and auto-shutoff — you’re guarded against unit failure mid-project.

This tool comes from the Extech stable — a US testing equipment specialist backed by over 50 years of experience. The MA445 is a mid-range clamp meter in its expansive multimeter line-up.


  • Weight – 9.3 ounces
  • Voltage – 600 volts
  • Current – 400 amps
  • Safety Rating –Cat III


  • Large LCD screen.
  • 1.2-inch jaw.
  • Non-contact voltage detector.


Includes 3 x AAA batteries.
Temperature testing.
CAT III rated.
In-built flashlight.
Min/Max and Hold functions.


Sluggish response.
Defaults to AC current on start-up.

Features and Benefits of the Extech MA445

It’s a no-nonsense, effortless operation clamp meter — but does the MA445 still have sufficient features to assist the enthusiastic amateur and light contractor?

Let’s dive right into the detail.

True RMS Technology

If nothing else, the MA445 Extech Clamp Meter is an impressively accurate testing unit.

Featuring TRMS (True Root Mean Square) tech, it promises more reliable accuracy than regular RMS machines. In simple terms, it compensates for electrical noise interference from neon lights, motors, and transformers that will otherwise skew your circuit testing results.

If you’d like to discover more about TRMS and what it means for your multi or clamp meter — check out my What Is The Meaning and Importance of Multimeter TRMS article.

Non-Contact Voltage Detector

Electricity is darn awesome — it powers TVs, drives hammer drills, and starts your car. But, it can also deliver particularly unpleasant shocks, and in worst-case scenarios, stop your heart from beating.

Hence, it’s reassuring to see that the Extech MA 445 incorporates a non-contact voltage detector. This welcome feature checks for the presence of electrical current, without you having to make direct contact with the circuit — emitting an audible warning should one be discovered.

Not just an advantage for trade contractors who are testing a multitude of systems in a working week, but also for amateur users whose knowledge of electrical wiring may be somewhat lacking.

Backlight and Flashlight

The generously-sized LCD screen features an integrated backlight, increasing the readout visibility that’s essential for poorly lit or nighttime conditions.

What’s more, the Extech Multimeter MA445 also boasts an in-built flashlight, adding welcome illumination in challenging light environments — such as in basements, beneath floorboards, and inside car engine bays.

Temperature Testing

The MA445 Extech possesses a temperature testing system — rare on lower-priced clamp meters. An included thermo-probe can detect heat levels from -40 to 1832 degrees Fahrenheit.

This is an all-important feature for pros or amateurs troubleshooting HVAC systems, working on automotives, or investigating printed circuit boards.

CAT III Rating

Although the Extech Clamp Meter MA 445 is a back-to-basics unit — it’s still rated for CAT III applications. Crucial for the trade pro, it permits the machine to be used on three-phase electrical systems — typical of warehouses, factories, and industrial locations.

However, bear in mind that high-energy systems — such as utility transformers — require a CAT IV machine.

If you want to learn more about the different CAT certification levels — check out my CAT Safety Rating 101.

Memory and Storage

I have trouble recalling what I had for breakfast — so I have literally no chance of remembering the readings from my multimeter as I search for a pen and pencil. If you’re similarly mentally challenged as me, you’ll probably welcome the memory feature of the Extech Multi Meter MA445.

Firstly the machine features a MIN/MAX system, delivering at the flick of a switch the highest and lowest circuit readings most recently made by the machine. Furthermore, this clamp meter offers a data hold setting — storing your results while you find a pen, laptop, or cell phone to record the results.


Despite the Extech Clamp MA445 being a budget-focused machine, it still possesses the versatility to address a plethora of circuitry issues — making it more than adequate for the casual home-user and light contractor.

This machine has the ability to address:

  • AC and DC voltage.
  • AC and DC current.
  • Resistance.
  • Type-K temperature.
  • Capacitance.
  • Diode testing.
  • Non-contact voltage.
  • Frequency.
  • Continuity

Battery Warning and Shut Off

You don’t want your clamp meter to fail mid-project due to draining or dead power cells — not only does it waste time, but it can also be hazardous if you’re left exposed to bare wires with no idea if they’re live.

Therefore, it’s comforting that the Extech MA-445 has a low-battery warning light — alerting you should the cells begin to fail.

Furthermore, this clamp meter features a pleasing auto-shutoff system, powering down the unit if it remains unused for five minutes or more — saving valuable battery life.

Additional Accessories

If you purchase the Extech Multi-Clamp Meter MA445 — you don’t just receive the base unit in the box. Additionally, you also get to enjoy:

  • Type K temperature probe.
  • Two testing leads.
  • Soft carry pouch.
  • Three AAA batteries.

Extech True RMS 400A MA 445 Specifications

Extech MA445
Weight9.3 ounces
Jaw Size1.2 inches
Voltage600 Volts AC/DC
Current AccuracyAC ±2.5% / DC ±2.0%
Voltage AccuracyAC ±1.2% / DC ±0.8%
AC Current400 amps
Highest Safety RatingCAT III
Size9.0 x 3.0 x 1.6 inches
Batteries3 x AAA
Frequency1 MHz
Capacitance40 MΩ
Resistance40 MO
Temperature Range-40 to 1832 degrees Fahrenheit

What Do Users Say About the Extech TRMS MA445?

In my eyes, the Extech Clamp MA445 is a reliable and relatively low-priced machine that would appeal to the ambitious amateur and light-project contractor.

Yet, with time-limited experience of this machine, and restricted application use, my views may be a little inaccurate. Therefore, to guarantee the most precise Extech Clamp Meter review possible — I sought the opinions of owners of the MA445.

Not only were these guys generally positive in their testimonials, their judgments virtually mirrored my own. Users of the Extech machine praised the inclusion of a flashlight, applauded the reassuring CAT III rating, and welcomed the precision of TRMS technology.

To be fair, there were a couple of negative sentiments expressed. One trade-pro reacted with dissatisfaction over the sluggish response in delivering circuitry results. Additionally, a disgruntled DIYer was annoyed that the machine always defaulted to AC current when activated, instead of keeping the last user setting.

However, all owners agreed that the Extech MA/445 offers an excellent price-to-quality ratio — and offered sufficient flexibility for the home-user and light-project pro.

Alternatives to the Extech Multi Clamp MA 445

Although it’s difficult to find any major faults with the Extech MA-445, it may not suit all users. Different personal preferences and project requirements may make the clamp meter less than ideal.

Hence, if the Extech is lacking in certain areas for you, consider the following impressive alternatives.

Klein Tools CL600

If you’re a hardcore contractor dealing with high-energy loads — then the Extech with its CAT III rating will be insufficient. Instead, consider this clamp meter model.

The Klein CL600 is certified for CAT IV use — making it a true industrial grade unit capable of reading mains utility junctions and cables. Pleasingly, it’s available at a similar price point to the MA445, and also boasts the precision of TRMS technology.

  • No in-built flashlight, unlike the Extech.
  • Rated to 1000 volts, as opposed to the 600 volts of the MA 445.
  • Like the Extech, the CL600 arrives with testing leads and a carry pouch.

Klein Tools CL380

Should the CAT III rating of the Extech clamp meter appeal, but you’re concerned about the durability of the unit — consider this machine from Klein Tools.

While the CL380 and MA445 share the same, three-phase compatibility rating — the Klein model boasts a drop-proof build, not a feature of the MA445. This shields the unit against falls from heights up to 6.6 feet — delivering reassuring robustness.

  • Rated to 600-volts, the same as the Extech.
  • A TRMS machine, identical to the MA445.
  • Slightly harder on the wallet than the Extech clamp meter.

Fieldpiece SC680

If you’re not keen on a back-to-basics clamp meter, and would prefer something a little more premium — check out this machine.

Boasting wireless technology, the CAT IV-rated SC680 can communicate with portable devices such as cells and tablets. Working via the Job Link App, it permits you to send and record readings over distances up to 30 meters.

  • Rated for 1000 volts, opposed to the 600 volts of the Extech.
  • Significantly harder on the wallet than the MA445.
  • Like the Extech, it incorporates a temperature testing facility.


Straightforward and no-nonsense, the Extech MA 445 Clamp Meter is a reliable and fuss-free machine for the home, garage, and light-contractor users.

Its CAT III rating permits use in three-phase environments, while a backlight and integrated flashlight allow operation in challenging illumination conditions. With a temperature testing system, it’s suitable for both HVAC and automotive enthusiasts — and TRMS tech ensures the most accurate of circuitry readings.

Of course, the unit isn’t going to connect with everyone. It isn’t compatible with high-energy outdoor utility looms, and the slow responsiveness may be an issue for time-short trade pros.

But, if you want a no-frills tool that has more than sufficient versatility for home and light project application — I suggest considering the Extech MA445 Clamp Meter.

Extech Clamp Meter MA 445 FAQs

Q: What Is the Extech Multimeter MA445 Price?

The Extech MA-445 clamp meter incorporates TRMS tech, a flashlight, and a non-contact voltage detector. To check out the current cost of the Extech MA445.

Q: Where Can I Find the Extech TRMS 400A MA445 Manual?

The official Extech website is host to a large range of user guides and instructions for its testing equipment. For rapid access to the Extech MA445 manual.

Q: What Batteries Does The Extech M A445 Use?

The Extech Meter MA445 requires three AAA batteries. Pleasingly, these are supplied in the unit purchase.

Q: Where Can I Buy the Extech Clamp Meter MA445?

The MA445 from Extech is a CAT III-rated clamp meter making it suitable for use in three-phase environments. You can get your hands on this machine by clicking here.

Q: What Is the MFD Range of the MA 445 for Checking Capacitors?

According to the specifications given by Extech, the MA 445 clamp meter is capable of testing up to 4000 µF (microfarads).

Q: Is Extech a Good Make of Clamp Meter Testers?

Yes. Extech Instruments is a US company operating out of Nashua, New Hampshire. It manufactures a plethora of testing equipment from its manufacturing hubs in Hong Kong, Shanghai, and Taiwan.

With a history dating back to 1971, it is renowned for its high-quality and precise products for both consumer users and trade professionals.

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