Megger has a long and rich history of providing the world with electrical test and maintenance solutions.  Over the course of 130+ years, we have grown and diversified in tandem with the electrical industry to stay at the forefront of customer needs.


Learn more about the milestones of our growth in the History of Megger timeline below. 


Sydney Evershed invents the insulation tester, or the “Megger”, and made possible the safe installation and working of electrical distribution systems.  These ground-breaking instruments are the direct antecedents of every insulation tester in use in the world today.


  • 1903 – Megger is registered as a trademark by Sydney Evershed and Ernest Vignoles
  • 1923 – The AVO Meter, the world’s first multimeter, is invented by Donald MacAdie and AVO Limited is formed
  • 1936 – James G. Biddle Co, an importer of Megger units, is incorporated in the US and develops battery test and cable fault location equipment
  • 1946 – The first commercial cable fault location device is developed at Biddle
  • 1951 – Multi-Amp is founded in Dallas, Texas, and focuses on the development of relay and circuit breaker test equipment
  • 1965 – The first low-voltage insulation power factor test set is developed at Evershed & Vignoles and, remarkably, weighs only 6.5kg.


The millionth AVO Meter (the Model 8 Mark 3, manufactured in the summer of 1965 in Dover, England) is sold

1968 – 1995

  • 1968 - AVO Limited acquires Evershed & Vignoles (Megger)
  • 1976 – Programma launches the first portable relay tester in the world
  • 1984 – The first microprocessor-controlled circuit breaker analyser is developed by Programma
    – The first 3 phase relay tester is developed by Multi-Amp
  • 1988 – The first portable dielectric frequency response analyser for insulation diagnostics is developed by WaBtech (later acquired by Programma)
  • 1995 – Megger, Biddle, and Multi-Amp join together to become AVO International


AVO International is renamed to Megger

2007 - 2021

  • 2007 – Programma (Sweden), a company of experts that specialise in transformers and circuit breakers, joins Megger Group
    – Megger develops the first portable cable fault location device with more than 2000 J
  • 2008 - PAX Diagnostics (Sweden), a developer of specialist transformer diagnostics instruments, joins Megger
  • 2012 – Seba KMT (Germany), a global leader in cable testing, joins Megger Group
  • 2018 - Baker Instruments, innovators in the electrical testing of motors and generators, joins Megger Group
  • 2019 - Power Diagnostix, an authority and supplier of products and services dedicated to the measurement and monitoring of partial discharge on high voltage installations, joins Megger Group
  • 2021 - Megger acquires Metrycom, introducing grid sensors and software (Megger Grid Analytics) to our portfolio
    - Megger partners with IPS, a leading provider of data analytics and digital asset management services to the electrical power industry
  • 2023: Megger acquire a subset of Weidmann, introducing Insulogix to our transformer offering, and AVO Diagnostic Services to our brand portfolio