Marmonix MCA204 (MCA 204 / MCA-204) AC Clamp Meter, 600 A True RMS

The Marmonix MCA204 clamp meter, also written MCA 204 or MCA-204, measures AC current up to 600 A through its jaw with True RMS response from 40 Hz to 1 kHz, and AC or DC voltage up to 600 V through the test leads. The same 172 g body adds an inrush mode that keeps the peak of the first 100 ms of a motor start, a non-contact voltage (NCV) sensor, a Type-K input for −30 to 1000 °C, resistance to 40 MΩ, capacitance to 4 mF, frequency to 1 MHz, diode and continuity, shown on a backlit 4000-count display with a built-in work light. It does not read DC amps, and its safety rating is CAT III 600 V. See how it compares with the other Marmonix clamp meters, or follow the step-by-step guide to using a clamp meter safely.

Why choose the MCA204 clamp meter for AC fault-finding

Here is what the MCA-204 changes on a typical service call:

• Trustworthy current on drives and LED loads: True RMS sensing to 600 A AC, so distorted waveforms do not skew the reading.
• See the real motor start, not just the running amps: inrush mode records start-up current in a 100 ms window.
• Check for live voltage before you touch: built-in NCV flags a live conductor without contact.
• Leave the separate multimeter behind: diode, continuity and duty cycle, plus 40 MΩ resistance, 4 mF capacitance and 1 MHz frequency.
• Temperature on the same meter: the Type-K probe covers –30 to +1000 °C (–22 to +1832 °F).
• Readable in a dark riser or ceiling void: backlit 4000-count LCD plus a built-in flashlight.
• Rated for distribution-level work: CAT III 600 V safety category.

How the MCA-204 works in daily use

Auto-ranging picks the scale for you and the display refreshes 3 times per second, so you clamp, read and move on. The controls you will use most are listed below:

• Freeze a reading you can’t see: data hold keeps the value on screen after you pull the jaw out of a tight panel.
• Track swings and peaks: MAX/MIN, peak hold and REL (relative) modes.
• Battery you can buy anywhere: 2 × 1.5 V AA cells, with auto power-off and a low-battery alert.

Case study: a compressor that trips its breaker only on start

An air-conditioning outdoor unit hums for a moment, then its breaker opens as the compressor tries to start. A running-current reading taken afterwards looks normal, which is why this fault is easy to miss. An AC-only True RMS clamp meter can measure the start itself:

• Find the live conductor: hold the Hz/NCV key for 2 seconds; strong beeps mark the line conductor, weak or no beeps the neutral.
• Confirm the supply: with the leads in COM and VΩHz, the meter detects AC or DC volts on its own.
• Catch the start-up peak: press HOLD twice until INRUSH appears, centre one conductor on the jaw mark, then start the compressor; the display keeps the highest current of the first 100 ms.
• Finish the diagnosis: compare that peak with the breaker and the compressor nameplate, then, with power isolated and the capacitor discharged, read its µF value and clip the Type-K probe to the refrigerant line.

Start current, capacitor value and line temperature all come from one meter, so the service sheet records measured numbers instead of a guess.

MarMonix MCA204 specifications

Every range, resolution and accuracy figure is listed in the datasheet table below.

MCA204 clamp meter FAQ

Does the MCA204 measure DC current?

No. Its jaw senses alternating current only, up to 600 A between 40 Hz and 1 kHz. DC voltage up to 600 V can still be read through the test leads.

How accurate is the MCA 204 on AC amps?

The published table gives ±(2.5% + 8 digits) on the 40 A, 400 A and 600 A ranges and ±(5% + 5 digits) on the 4 A range.

Can I stop the MCA-204 switching off during a long test?

Yes. Hold the Hz/NCV key while turning it on; five beeps confirm auto power-off is disabled. Otherwise it switches off after 15 minutes without use.

More from MarMonix

Compare alternatives or pick the right tool type with these pages:

• All MarMonix clamp meters
• MarMonix digital multimeters
• Clamp meter vs multimeter: buyer’s guide