Electrical Insulation Testing | What? Why? When? How?....

What is an insulation test?

It's a test carried out to determine the condition of the insulating materials which cover the live parts of any electrical circuit. 

Why do we conduct an insulation test?

To determine the electrical safety of the equipment being tested

To monitor the deterioration of insulating materials as part of a maintenance process 

As part of a fault finding process

When should we conduct an insulation test?

Before and after maintenance/repair work

During a fault finding process

As part of periodic inspection and testing

How to conduct an insulation test

When carrying out an appliance insulation test through the plug it's actually very straight forward to do:

Attach one of the test leads across both the live and neutral pins together (important) and the other to the earth pin. 

Ensure the test meter is set to Insulation/500v DC and quite simply press the test button (will vary depending on the test meter)

From the reading show we can determine what, if any, action is required. The minimum pass requirement is 2 Mega Ohms. Reference Image 1. The display reads 999 Million Ohms of resistance between the live parts and earth. In layman terms.....The insulation test is a pass.

Image 1.