For over a century, Megger has been synonymous with quality and reliability in portable electrical test equipment. But where did the famous Megger name, a guarded trademark of Megger Group Limited, come from?

Back in 1888, electric lighting was growing in popularity. Sidney Evershed was working for Goolden & Trotter, a company with a department that specialized in domestic installations. To verify the safety of those installations, a method of testing insulation was needed. At that time, insulation resistance could only be measured in a laboratory, and the measurements were carried out at low voltages, typically around 2V.

Evershed knew from research that testing at such low voltages gave unsatisfactory results, and to ensure the safety of an installation, it was essential to test the insulation at its working voltage or higher. He also knew that the laboratory techniques for measuring insulation resistance were unsuitable for use on site.

His response was to develop the first direct-reading ohmmeter, which comprised a small permanent magnet suspended at the center of, and controlled by two coils at right angles to each other. One coil was connected directly to the voltage source energizing the ohmmeter; the other was connected to the same voltage source via the insulation under test. This meant that the results obtained were independent of the voltage.

Evershed energized his ohmmeter with a hand-cranked generator, similar to the type in use at the time for ringing telephones. The instrument proved so successful that Evershed patented it, and Goolden & Trotter started to manufacture and market it in 1889.

In 1895, Sidney Evershed and Ernest Vignoles, another Goolden & Trotter director, purchased the company’s instrument department and set it up as Evershed & Vignoles Limited. The insulation testers made by them were given the name Megger. On May 25, 1903, the company registered the word Megger as trademark number 254820 in the UK. It has since been registered in almost every country.

The exact date the word Megger was first used is not known, but it is believed Vignoles devised it. Some sources suggest that it is a contraction of the words MEGohm and metER, with the addition of a G, while others suggest that the original words were MEGohm and testER. Either way, the result is one of the best-known and respected trademarks in the electrical industry worldwide.

On Washington’s birthday in 1895, while Evershed and Vignoles was being set up in England, James G. Biddle started his own business in Philadelphia. He acted as a manufacturers agent, arranging to import and sell scientific and electrical equipment made by overseas manufacturers.

In 1910, Dr. Rowland, Electrical Department head at Philadelphia’s Drexel Institute told Biddle about a device for measuring insulation resistance that was manufactured in England by Evershed & Vignoles, and that this company was, with the aid of the British Consul in Philadelphia, looking for US representation.

Biddle traveled to England and, with a handshake, concluded a deal with Evershed & Vignoles, which made his company the sole distributor in the US for all Evershed & Vignoles test equipment, which included Megger insulation testers, earth testers and Ducter low-resistance ohmmeters.

Initially, Biddle ordered five Megger insulation testers, which he sent out on consignment to his close engineering acquaintances and public utility companies. Four out of five recipients decided to buy the instrument they had been sent. The success of the products helped Biddle to expand his operations. In 1936, the business was incorporated as the James G. Biddle Company.

Biddle retired in 1940, and in 1945 was appointed Chairman of the Board. During World War II, because of the difficulty of obtaining equipment from England, Biddle started its own manufacturing operation for Megger insulation testers in the US.

After several ownership changes, Evershed and Vignoles joined forces with AVO Limited, the company that developed the world’s first multimeter, to form Megger Instruments. In 1991, Biddle and Megger, along with Multi-Amp, came together to form the organization then known as AVO Megger Instruments.

Today, the organization is known as Megger Group Limited. With development and manufacturing facilities in the US, the UK and Sweden it is, and has been for more than 100 years, a world leader in the electrical test equipment field.

The Megger name is so well known that it is incorrectly used as a verb that means “to perform an insulation test.” Megger remains a registered trademark and Megger Group rigorously defends and takes all necessary steps to address improper usage that come to its attention.