How to use a Klein ET600 megger

The Klein ET600 is used to check insulation resistance on motors, cables, windings, and other electrical equipment by applying a test voltage of 125V, 250V, 500V, or 1000V and reading the insulation value in megaohms. It can also measure AC/DC voltage up to 1000V and resistance/continuity, but the insulation test is the main “megger” function.

Safe setup

Before testing, make sure the circuit is de-energized and isolated, and read near 0V on the meter before touching the leads. Use the proper CAT-rated leads, verify the meter and leads are in good condition, and follow the unit’s safety guidance because insulation testers can generate very high voltage.

Basic steps

  1. Turn the rotary switch to the insulation resistance test mode.
  1. Choose the test voltage that matches the equipment you are checking, such as 125V, 250V, 500V, or 1000V.
  1. Connect one lead to the conductor or winding under test and the other lead to the other side of the insulation path, usually ground or the opposing conductor.
  1. Press and hold the test button, or use the lock feature for hands-free testing when appropriate.
  1. Read the insulation value on the display in megaohms.
  1. Release the test and let the circuit discharge fully before removing the leads.

Picking voltage

A common rule shown in demonstrations is to use a test voltage that fits the equipment’s normal rating, rather than automatically jumping to the highest setting. For example, one demo used 250V on a smaller motor instead of 500V. The ET600 supports 125V, 250V, 500V, and 1000V insulation testing, so the correct choice depends on the device you’re testing.

What the reading means

Higher insulation resistance is generally better, because it suggests less leakage through the insulation. A low reading can point to damaged, wet, dirty, or failing insulation, and a very low reading may mean the part should not be returned to service until it is inspected. The exact pass/fail threshold depends on the equipment and the maintenance standard being followed.

Practical example

If you are testing a motor winding, you might disconnect the motor, connect one lead to the winding and the other to the motor frame or ground, choose a voltage that matches the motor, then press test and watch the megaohm reading. Afterward, use the test button to stop the output and confirm the circuit is discharged before removing the leads.

Things to avoid

Do not test live circuits for insulation resistance, and do not touch the conductors while the test is active. Do not assume 1000V is always better; using too high a test voltage can be unnecessary for smaller equipment. And after every test, make sure the circuit has fully discharged before handling it.

TL;DR

Set the ET600 to insulation test, choose the correct voltage, connect the leads to the isolated circuit, press test, read the megaohms, then let everything discharge before removing leads.