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Extech · Extech MA1500 1500A True RMS AC/DC Clamp Meter with NCV | 1500A AC/DC, True RMS, 0.7in jaw, variable frequency control (VFC), low pass filter, NCV, relative
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Verdict
The Extech MA1500 is a True RMS AC/DC clamp meter rated to 1500 A with a jaw only 17 mm across. That pairing seems contradictory until you consider where high currents run through single, moderately sized conductors: motor leads in a control centre, DC bus bars in a drive cabinet, battery cables and welding leads. The compact jaw gets into those places while the sensor reads currents far beyond a standard 600 A clamp. A variable frequency control low-pass filter handles drive outputs, a relative function zeroes the DC offset, and a built-in non-contact voltage detector screens for live conductors. What it cannot do is enclose a large feeder or a bundle, which is the job of the Fluke 355 with its 58 mm jaw. Within its niche, the documentation supports it as a well-judged tool.
Who It Is For
- Industrial electricians working inside motor control centres and drive cabinets.
- Technicians on DC systems: battery banks, rectifiers, electroplating and welding.
- Anyone who needs high current readings in confined spaces.
Documented Specifications
| Item | Documentation |
|---|---|
| Current | AC and DC to 1500 A, True RMS |
| Jaw | Compact 0.7 inch (17 mm) for tight locations |
| Drive measurement | Variable Frequency Control (VFC) low-pass filter |
| Functions | AC current, relative function, non-contact voltage detector |
The voltage range, resistance and other functions, the display count and the safety category rating are on the manufacturer’s datasheet; consult the current revision before relying on a figure.
High Current Through a Small Jaw
Current density in industrial conductors is high: a single cable of the size that fits a 17 mm jaw can carry hundreds of amps, and busbar tabs and motor leads at that size routinely see a thousand. Full-size 1000 A clamps have jaws that will not fit between adjacent terminals in a drive cabinet, so technicians end up measuring at a more accessible but less informative point. The MA1500’s design accepts that it will not fit a bundle and instead puts a high-range sensor behind a jaw that fits where the current is. DC through a Hall-effect sensor drifts, so the relative function should be used with the jaw closed on nothing before each DC reading; owners note that this is essential at the low end of the range. For the general technique see measuring current with a clamp meter.
The VFC Filter and Drives
The current on a drive-fed motor lead is the fundamental frequency the motor runs at plus a large amount of switching-frequency content. A True RMS meter without a filter includes the switching content and reads high and unsteadily. The VFC low-pass filter removes it so the reading corresponds to the motor’s real current and can be compared with the nameplate. The same filter helps on any electrically noisy circuit. Our article on measuring AC voltage covers the same issue on the voltage side.
NCV Detector and Build
The built-in non-contact voltage detector screens for energised conductors before the jaw goes on, which matters inside a cabinet where not every conductor is labelled. It is a screening tool only. The meter is compact for its rating, and owners describe it as easy to hold one-handed in a cabinet. Like most Extech clamps it has no wireless logging.
Practical Notes
Because the jaw is small, it is worth confirming that the conductor sits centred and that the jaw closes fully; a partially open jaw on a high-current conductor reads low. The relative function should be used for every DC reading and repeated if the meter warms up in a hot cabinet. Owners note that the compact body means a small display, so a reading taken deep in a cabinet is often best captured with hold and read outside. On drive outputs, take the reading with the VFC filter on and again with it off; a large difference confirms that switching noise is present and that the filtered value is the one to record.
Strengths
- 1500 A AC and DC through a jaw that fits confined spaces.
- True RMS with a low-pass filter for drives.
- Relative function for DC zeroing.
- Built-in NCV detector.
Limitations
- 17 mm jaw excludes large feeders and bundles.
- No inrush capture noted on the listing.
- No wireless or logging.
How It Compares
The Fluke 355 reads 2000 A AC/DC through a 58 mm jaw and adds inrush, at a much higher price and size. The Extech EX840A stops at 1000 A but adds inrush, LoZ and an infrared thermometer with a larger jaw. The Extech MA445 is the 400 A general-purpose sibling for everyday panel work.
How We Research
This review is based on the manufacturer’s published specifications, the Amazon product listing and owner reports. We did not run laboratory tests.
Recommended Tools
Products shown because their documented specifications fit this guide. Price and availability are on Amazon and can change.
Frequently Asked Questions
How can a 17 mm jaw measure 1500 A?
The jaw limit is about the conductor diameter it can enclose, not the current. A 17 mm jaw fits a single conductor up to that size; the sensor inside is rated to read 1500 A through it. Very large or bundled conductors will not fit.
What is VFC?
Variable Frequency Control is Extech's name for a low-pass filter that removes the high-frequency switching content from a variable frequency drive output so the meter reads the fundamental current or voltage.
Does it read DC current?
Yes. AC and DC to 1500 A through the jaw, which covers DC drive, battery and rectifier circuits within the jaw size.
Is it True RMS?
Yes. The listing specifies True RMS for noisy, distorted and non-sinusoidal waveforms.
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