Megger

Megger is the principal brand of Megger Group Limited, a British manufacturer of electrical test equipment and measuring instruments. Its products are used by utilities, electrical contractors, industrial maintenance teams, manufacturers, rail and transportation operators, and other organizations responsible for electrical infrastructure. The company is particularly associated with insulation resistance testers, commonly known as Meggers, but its present portfolio extends across cable diagnostics, earth and ground testing, low-resistance measurement, power quality, electrical installation testing, portable appliance testing, current measurement, transformer diagnostics, battery testing, circuit-breaker testing, motor testing, and software for test-data management. The brand's roots lie in the instrument business acquired and developed by Sydney Evershed and Ernest Vignoles. They established Evershed & Vignoles Limited in 1895, building on electrical-instrument work that can be traced to the late nineteenth century. Evershed's hand-powered generator made it practical to produce sufficiently high voltages for measuring resistance in the megohm range. The resulting portable insulation tester became known as the Megaohm Meter, shortened to Megger. The Megger name was registered as a trademark in 1903 and became widely recognized among electrical engineers during the twentieth century. Early instruments were important because insulation deterioration can create leakage currents, short circuits, equipment damage, and safety hazards. Initial products separated voltage generation and measurement into different cases to limit electromagnetic interference. Later designs integrated the functions into portable cases, including the well-known Wee Megger and larger high-voltage instruments. The brand consequently became closely identified with insulation testing rather than with a single product model. Megger's corporate history includes successive combinations with other British and international electrical-instrument businesses. Evershed & Vignoles became part of the George Kent Group in 1965. The group was subsequently associated with Thorn Electrical Industries and Thorn EMI. AVO, whose Avometer multimeters originated in the 1920s, became part of the broader business alongside Biddle and Multi-Amp. The corporate identity passed through AVO Megger Instruments and AVO International before the name Megger Group Limited was adopted in 2002. H.W. Sullivan, a maker of precision laboratory instruments, was also incorporated into Megger in 2002. The group has expanded through acquisitions and brand integration. Its portfolio has included Biddle, States, PowerDB, Programma, Pax Diagnostics, SebaKMT, and Baker Instrument. These additions broadened the business from traditional handheld meters and insulation testers into cable-fault location, battery and transformer diagnostics, power-system testing, rotating-machine analysis, and digital test records. In 2018 Megger acquired Baker Instrument from SKF, adding established equipment for testing and diagnosing electric motors and other rotating machines. In 2025 it was reported to have acquired Sentrisense, an Argentine technology company developing real-time monitoring systems for overhead power lines. Megger operates internationally through manufacturing, engineering, sales, service, and training activities. Its associated AVO Training Institute provides education in electrical safety, maintenance, testing, and power-system engineering, including arc-flash studies. The company therefore competes not only as a hardware supplier but also as a provider of diagnostic knowledge, testing workflows, and condition-monitoring tools. Its positioning is technical and professional: instruments are intended to generate reliable measurements that support commissioning, preventive maintenance, fault finding, regulatory compliance, and asset-life decisions.

Megger's history begins with the development of portable electrical instruments in Britain during the late nineteenth century. Sydney Evershed and Ernest Vignoles worked in the instrument trade before acquiring the relevant instrument section of Golden Trotter and founding Evershed & Vignoles Limited on 5 February 1895. The business was associated with Acton Lane Works in London after moving from Westbourne Park in 1903. Sydney Evershed patented several electrical devices, including a hand dynamo capable of generating voltages suitable for high-resistance measurement. This enabled the development of a portable insulation tester for measuring resistance in the megohm range. The product became known as the Megaohm Meter, abbreviated to Megger. The Megger trademark was registered on 25 May 1903. By the 1920s, insulation testing with a Megger instrument was widely familiar among engineers. Product designs evolved from two-box arrangements, used partly to manage electromagnetic interference, to integrated portable units in Bakelite cases. The Wee Megger became a particularly recognizable model, while larger instruments offered substantially higher test voltages and resistance ranges. The business grew substantially during the first half of the twentieth century. Employment was reported at approximately 500 people in the 1920s and rose during the Second World War. The workforce later reached a reported peak of about 1,870 in 1967. In 1965 Evershed & Vignoles became part of the George Kent Group. The group was later connected with Thorn Electrical Industries and Thorn EMI, whose corporate changes brought additional instrument businesses into the same ownership structure. A major strand of Megger's heritage came from AVO. The Automatic Coil Winder and Electrical Equipment Company was formed in 1922 to exploit Donald MacAdie's patents for an automatic coil winder and a combined ampere, volt, and ohm meter. The first AVO meter entered the market in 1923. AVO instruments, particularly the Model 8 introduced in 1951, became widely used in British industry, education, research, telecommunications, military work, and maintenance. The AVO line continued through successive versions, with the last Model 8 Mk 7 produced in 2008. AVO also made signal generators, valve testers, specialist radio-service instruments, and other electronic equipment. Biddle and Multi-Amp added further capabilities. Biddle operated in the United States as an importer and manufacturer associated with Megger products and developed BITE battery-impedance test equipment. In 1991 Biddle, Megger, and Multi-Amp joined to form AVO International. The company subsequently passed through the names AVO Megger Instruments Limited and AVO International Holdings Limited. In 2002 it became AVO International Limited and finally adopted the name Megger Group Limited. H.W. Sullivan, a precision-instrument manufacturer established in 1922, was incorporated into Megger in the same year. The modern group expanded through a series of acquisitions and integrations. It acquired PowerDB in 2005, adding software for acceptance and maintenance test-data management. Programma Electric, a Swedish maker of circuit-breaker, battery, primary-injection, vacuum-interrupter, and protective-relay test equipment, joined Megger in 2007. Pax Diagnostics, founded by former Programma employees and focused on transformer testing and insulation diagnostics, was acquired in 2008. SebaKMT joined the group in 2012, strengthening cable-fault location, cable testing, and pipe-leakage detection. In 2018 Megger bought Baker Instrument from SKF, bringing motor and rotating-machine testing into the portfolio. Megger's present identity combines its historic insulation-testing trademark with the names and technologies of acquired businesses. The group maintains operations and sales channels around the world, with the Dover site serving as a significant UK location. Its activities cover product engineering, manufacturing, training, technical support, and asset-diagnostic software. The business remains focused on helping customers commission, maintain, troubleshoot, and extend the service life of electrical equipment and power infrastructure.

• 2025

  Sentrisense acquired

  [1]Meggeren.wikipedia.org

  Megger acquired an Argentine developer of real-time overhead power-line monitoring technology.

• 2018

  Baker Instrument acquired

  [1]Meggeren.wikipedia.org

  The transaction expanded Megger's motor and rotating-machine diagnostic capabilities.

• 2012

  SebaKMT acquired

  [1]Meggeren.wikipedia.org

  Megger acquired a specialist in cable fault location, cable testing, and pipe-leakage detection.

• 2007

  Programma joins Megger

  [1]Meggeren.wikipedia.org

  The Swedish electrical test-equipment business became part of Megger Group.

• 2005

  PowerDB acquired

  [1]Meggeren.wikipedia.org

  The acquisition added acceptance and maintenance test-data management software.

• 2002

  Megger Group Limited name adopted

  [1]Meggeren.wikipedia.org

  Following earlier AVO Megger and AVO International identities, the company adopted its current group name.

• 1991

  Biddle, Megger, and Multi-Amp form AVO International

  [1]Meggeren.wikipedia.org

  The combination created a broader international electrical test-equipment organization.

• 1965

  Evershed & Vignoles joins George Kent Group

  [1]Meggeren.wikipedia.org

  The historic Megger predecessor became part of the George Kent Group.

• 1923

  First AVO multimeter marketed

  [1]Meggeren.wikipedia.org

  The first AVO instrument was sold following the formation of the Automatic Coil Winder and Electrical Equipment Company.

• 1903

  Megger trademark registered

  [1]Meggeren.wikipedia.org

  The name Megger, derived from Megaohm Meter, was registered as a trademark.

• 1895

  Evershed & Vignoles founded

  [1]Meggeren.wikipedia.org

  Sydney Evershed and Ernest Vignoles established Evershed & Vignoles Limited in Britain.

A specialist, professional-grade supplier of electrical test, measurement, diagnostics, and condition-monitoring equipment for power utilities, industrial operators, electrical contractors, equipment manufacturers, and maintenance engineers.

• Insulation testing

  Megger insulation testers

  Portable instruments that apply a controlled test voltage and measure insulation resistance in electrical circuits, cables, motors, transformers, and other assets. The product family is the foundation of the Megger name and is used for commissioning, preventive maintenance, fault investigation, and electrical-safety assessment.

• Electrical measurement · 1923

  AVO multimeters

  The AVO line originated with a combined ampere, volt, and ohm meter first marketed in 1923. Its best-known Model 8 became a long-running analog instrument used in industrial, educational, research, military, and maintenance settings. The historical AVO range also included electronic meters and specialist instruments.

• Cable diagnostics

  SebaKMT cable-fault systems

  Systems for locating and testing faults in power cables, including technologies associated with arc-reflection methods. The SebaKMT portfolio also brought expertise in pipe-leakage detection and strengthened Megger's utility-infrastructure offering.

• Motor and rotating-machine diagnostics

  Baker motor-testing equipment

  Equipment for evaluating electric motors and other rotating machines, including online and offline diagnostic applications and surge-testing capabilities. Baker became part of Megger in 2018 after its acquisition from SKF.

• Test-data management software

  PowerDB

  Software used to organize acceptance and maintenance test information and connect electrical test procedures with structured digital records. Its acquisition extended Megger's offering beyond instruments into documentation and asset-maintenance workflows.

• Overhead-line monitoring

  SENTRI

  A lightweight autonomous field sensor developed by Sentrisense for overhead power lines. The platform combines dynamic line rating, asset-health monitoring, and cable-theft detection, while measuring conditions such as sag, vibration, temperature, and tilt and transmitting data to a cloud platform.

• 2025

  Acquire SentrisenseM&A

  Background

  Utilities increasingly require real-time visibility into overhead-line capacity, asset condition, reliability, and theft risks.

  Action taken

  Megger acquired Sentrisense, adding its SENTRI sensor and cloud-based SENSE monitoring platform.

  Aftermath

  The acquisition extended Megger's portfolio toward grid modernization, dynamic line rating, and continuous asset monitoring.

  Source

• 2018

  Acquire Baker Instrument from SKFM&A

  Background

  Megger sought to broaden its electrical test portfolio into motor and rotating-machine condition assessment.

  Action taken

  Megger purchased Baker Instrument from SKF on 19 August 2018; the reported transaction terms were undisclosed.

  Aftermath

  Baker's motor-testing and diagnostic capabilities complemented Megger's existing power-system and electrical-maintenance products.

  Source

1. 1Meggeren.wikipedia.org