It supplies products related to the following areas: cable fault locating, earth/ground testing, low resistance measuring, power quality, electrical wiring, insulation testers, multimeters, portable appliance testers, clamp-on meters, current transformers, etc.

[4][5] One of them was for a "hand dynamo",[6] which allowed the generation of voltages high enough to measure resistance in the megohm range and facilitated the construction of the first portable insulation tester.

[8][9] Due to electromagnetic interference, the first Megger insulation testers were built as two separate boxes – one for voltage generation, and one for measurement.

[16] The invention of the first multimeter is attributed to Donald Macadie (1871–1955) [17][18] who was the manager of the Post Office Telephone Factory in Holloway, North London.

[19][20] It has often been stated that Mr. MacAdie devised the Avometer because he became dissatisfied with having to carry many separate instruments required for the maintenance of the telecommunication circuits.

[21] However the accuracy of the story may be questioned because it is unlikely that a senior Post Office Engineering manager would have been carrying around his own instruments.

Macadie invented a first instrument, which could measure Amps, Volts and Ohms, so the multifunctional meter was then named as AVO.

Some designs were produced especially for specific industries (e.g. Model 12 for Auto-electrical work) and at the request of large companies, the British armed forces and later NATO.

In 1996 the Institute was certified with ISO 9001 and so far over 230,000 electrical maintenance and testing technicians and engineers from around the world have attended training courses.

[28] The Institute has a Technical Resource Center – an online store offering books, standards, training materials, Personal Protective Equipment, and tools.

[30] The AVO Electrical Engineering Division was created in 2002 and it specialises in power system studies, specifically arc flash hazard analysis.

For many years, the James G. Biddle Company in Pennsylvania, was the United States importer of Megger products, as well as a manufacturer of equipment under their own name.

In 1989, using concepts introduced by Commonwealth Edison Company of Chicago, Biddle started development of a range of equipment to test the integrity of large battery systems, which led to the BITE (Battery Impedance Test Equipment) line of products.

[42] In July 2012 Megger acquired SebaKMT specialising in power cable fault location and testing, and pipe leakage detection.

As a result, the Group's position on the market of test equipment for the electrical power sector increased significantly.

[46] It is difficult to assess the actual number of patents, because some of them were obtained before acquired companies joined Megger Group.

The table shows a timeline of some typical devices introduced by Megger Group companies (not necessarily covered with patents).

[47] In 2011 Megger's MFT1700 Multifunction Tester won the "Innovative Test & Measurement Product of the Year", at the Electrical Industry Awards.

[50] Megger also won in earlier editions, for instance in 2007 these were: multifunction tester MFT 1553 and portable cable fault location PFL40.

There are sales centres in several countries and products are also sold via specialised distributors including RS Components and more recently Test Equipment Connection Corporation.

[53] [54] There are total of 15 sales and technical support offices in the US, Canada, Dover, Paris, Mumbai, Sydney, and Bahrain.

Megger donated 5% of its Chinese sales revenue (for three months) to the local Red Cross after the 2008 Sichuan earthquake.

[58] Over $9,000 of electrical testing equipment has been donated to Mesalands Community College's North American Wind Research and Training Center (NAWRTC).