Extech MG320 CAT IV Insulation Tester/True RMS Multimeter
The Extech MG320 integrates a high-voltage insulation resistance tester (up to 20 GΩ at 1000 V) with a True RMS multimeter (AC/DC voltage, resistance, continuity). It’s engineered for demanding electrical work, with features like PI/DAR testing, programmable timers, comparator thresholds, and data storage — all in a rugged CAT IV enclosure.
Description
The MG320 is a hybrid instrument combining advanced insulation testing and general-purpose multimeter functions in one rugged handheld unit. As an insulation tester, it supports test voltages of 50V, 100V, 250V, 500V, and 1000V, and can measure insulation resistance up to 20 GΩ using automatic ranging. It includes specialized modes such as Polarization Index (PI) and Dielectric Absorption Ratio (DAR) to assess insulation quality over time.
The timer function allows technicians to set the duration for insulation tests, while the comparator mode lets you define pass/fail thresholds for quick, on-the-spot judgments. After a test, the instrument automatically discharges residual voltage for user safety.
On the multimeter side, the MG320 offers True RMS measurement of AC/DC voltage up to 600V, resistance up to 20 kΩ, and continuity testing. It also provides a “zero” function for low resistance, stores up to 99 readings, and has a large backlit 6,000-count display with an analog bar graph for clear readings in all conditions.
Safety-wise, the MG320 is rated CAT IV 600V, meaning it’s designed for the highest overvoltage category at the service entry level. The unit ships with test leads, an alligator clip, six AA batteries, and a soft carrying case for convenient field use.
Features
- Insulation Resistance up to 20 GΩ — Wide dynamic range for insulation testing.
- Multiple Test Voltages — 50V, 100V, 250V, 500V, 1000V selections.
- PI / DAR Modes — Polarization Index & Dielectric Absorption Ratio tests for insulation assessment.
- True RMS Multimeter — AC/DC voltage (up to 600V), resistance (to 20 kΩ), and continuity.
- Comparator / Pass-Fail Function — Set thresholds for insulation tests with visual/audio feedback.
- Programmable Timer — Define test duration for timed insulation measurements.
- Memory Storage — Store and recall up to 99 readings.
- Auto Discharge — Safely discharges test voltage when measurement ends.
- Large Backlit Display — 6,000-count display with analog bargraph for clear viewing.
- CAT IV 600V Safety Rating — Suitable for use at service panels and primary distribution.
Includes
- Test leads
- Alligator clip
- 6 x AA batteries
- Soft case
