Stellar Instruments CM320 TRMS Milli Amp AC/DC Clamp Meter

1. What is the CM320 used for?

It is a compact clamp meter for electrical testing, maintenance and troubleshooting. It measures AC and DC current up to 400 A, and it also offers inrush current measurement, non-contact voltage detection (NCV) and a low-pass filter (LPF).

2. Can it measure both AC and DC current?

Yes. It measures AC and DC current on two autoranging ranges, 40 A and 400 A. Resolution is 10 mA on the 40 A range and 100 mA on the 400 A range.

3. How accurate is it?

Accuracy is ±2.0% of reading + 5 digits for both AC and DC current. AC measurements use True RMS, which gives reliable readings even on non-sinusoidal waveforms.

4. What is the NCV function, and what voltage range does it detect?

NCV (non-contact voltage detection) lets you check whether a conductor is live without touching it. It detects AC voltage from 80 V to 600 VAC. Use it as a quick safety check only, and confirm with a proper voltage test before working on any circuit.

5. What is the largest conductor it can clamp?

The maximum jaw opening is 23 mm in diameter. It suits small and medium cables but will not fit large cables or busbars. For those, a flexible coil meter such as the Stellar CM910 is a better choice.

6. What are the power and physical specifications?

• Battery: 2 × 1.5 V AAA
• Display: 4-digit LCD, maximum reading 4200
• Sampling rate: 2 readings per second
• Dimensions: 149 × 59 × 28 mm
• Weight: 133 g