MJ159, MJ359, and 21017

Major Megger insulation resistance testers

  • Guard terminal to eliminate surface leakage current
  • Voltage indicating range
  • Portable tester
  • No scale multipliers
  • Multiple test voltages for spot and step voltage testing
  • Large, easy-to-read scale

Please note that the 210600 has been discontinued.

The MJ159, MJ359, and 21017 Major Megger insulation resistance testers provide excellent test voltage regulation and are ideal instruments when high ranges are needed for measuring insulation resistance. They also have an external guard terminal to eliminate surface leakage current from the measurement.

The instruments are all electronic; they generate a regulated DC high voltage and use low-zero-drift, high-accuracy circuits, with high current sensitivity. Designed for portability, each is enclosed in a molded, impact-resistance, flame-retardant case that is made with ABS plastic with a fold down carrying handle.

The MJ159 and 210170 are both operated by low voltage, hand-cranked generators that have been designed to be easy to turn even under full load conditions. The low voltage generator is connected to an electronic inverter to provide a very stable test voltage. Accuracy of measurement is unaffected by variations in the generator cranking speed and the test voltage is maintained at its rated value.

The MJ359 is powered by a 120 V AC 50/60 Hz or low voltage generator.

  • The MJ159 has four selectable test voltages of 100, 250, 500, and 1000 V DC. It measures insulation resistance up to 2000 MΩ, and an ohm range to 5000 Ω.
  • The MJ359 has the same features as the MJ159, but is powered by a low voltage generator.
  • The 210170 provides high-resistance readings up to 20,000 MΩ. The meter is calibrated directly in megohms, ohms and AC volts. Insulation resistance measurements up to 20 GΩ can be made on all voltage ranges. The 210170 is also equipped with a 0 to 5000 Ω continuity range and a 0 to 600 V AC or presence of DC voltage measuring range.

In all models, as a safety feature, the AC voltage range becomes effective as soon as the instrument is connected to the circuit under test. Therefore, a warning is given that the circuit under test is not de-energised before the instrument is operated. Though calibrated for AC voltage, this range also monitors the automatic discharge feature so that after equipment having capacitance (i.e., a cable), has been tested, an indication can be given that the voltage has discharged to a level that is safe for removing the test leads.

All three models are portable, self-contained instruments designed to give rapid and accurate measurements. The instrument is protected for connection to power distribution systems up to 300 V Line-Ground and 500 V Line-Line for Installation Category III. This relates to transient overvoltage likely to be found in fixed installation wiring.