"Megger" is a brand name for an Insulation Resistance tester. It creates a voltage (usually 500V) and allows you to test for any Insulation breakdown.
"Megger" originated from MegaOhm (that is what it measures) probably. It is brand name of measuring instruments company 'AVO' (currently part of Biddle, I think).
The term "Megger" is a Registered trademark in 32 countries of various Insulation Testors Mr. Biddle & Company produce...
I know several of the Inspectors from Hartford that will accept "Only" the readings from a "Megger"..
(James Biddle & Compny)
