Megger MIT220 MIT Series Insulation Resistance Testers

Megger MIT220 is a compact, battery-powered insulation resistance tester (megohmmeter) belonging to the highly regarded MIT200 Series. Known for its robustness and portability, this instrument is specifically designed for electrical contractors, maintenance engineers, and service technicians who need to perform insulation and continuity tests on motors, generators, cables, switchgear, domestic appliances, and industrial wiring systems.

Key Technical Specifications

One of the defining features of the MIT220 is its dual-voltage capability. The unit provides selectable DC test voltages of 250V and 500V, making it suitable for testing low-voltage equipment and systems up to 500V. For insulation resistance, the instrument measures up to 1000 MΩ (1 GΩ) , offering a wide range for identifying deteriorating insulation before failure occurs.

For continuity testing, the MIT220 delivers a short-circuit current of 200 mA , which meets the requirements of BS7671 and other wiring regulations. It features a resolution of 0.01 Ω , allowing for precise measurement of protective conductor continuity and bond resistance.

Display and Interface

The MIT220 utilizes a unique dual digital/analog display. While the digital display provides specific numerical values for precise recording, the analog arc (bar graph) allows the user to observe fluctuating or trending readings that are not always visible on a digital screen, such as the charging effects of capacitive circuits.

Safety and Usability Features

Safety is a primary focus of the MIT220 design. The unit features a live circuit warning and test inhibit function; if the tester detects a voltage greater than 50V AC or DC on the circuit, it will prevent an insulation test from being performed and alert the user. Additionally, it has an automatic voltmeter function that activates when connected to a live circuit above 25V.

The tester includes an automatic discharge feature, safely dissipating capacitive charge from the circuit under test after an insulation test is completed. For convenience, the unit supports automatic continuity testing (hands-free operation) and an auto power-down function to conserve battery life after 10 minutes of inactivity.

Physical Specifications and Environment

Weighing approximately 530g (1.2 lbs) and measuring 195 x 98 x 40 mm , the MIT220 is one of the smallest testers in its class, designed for easy carrying in a tool belt or bag. It is built to withstand harsh environments with an operating temperature range of -10°C to +55°C (14°F to 131°F) and meets the CAT III 600V safety standard, making it safe for use on industrial distribution boards and fixed installations. The unit is powered by 6 x AA alkaline batteries, providing enough capacity for approximately 3000 five-second tests.