Charles Hesterman Merz (5 October 1874 – 14 or 15 October 1940) was a British electrical engineer who pioneered the use of high-voltage three-phase AC power distribution in the United Kingdom, building a system in the North East of England in the early 20th century that became the model for the country's National Grid. Life Merz was the eldest son of industrial chemist John Theodore Merz (a Quaker from Germany) and Alice Mary Richardson, a sister of John Wigham Richardson the Tyneside ship builder. He was born in Gateshead and attended Bootham School, York. He attended Armstrong College in Newcastle, where his father was a part-time lecturer. He then entered an apprenticeship at the Newcastle Electric Supply Company (NESCo), which had been founded by his father, in 1889. In 1898 Merz became the first Secretary and Chief Engineer of the Cork Electric Tramways and Lighting Company in Cork, Ireland. In 1899 Merz set up a consulting firm which, with the arrival of William McLellan in 1902, became Merz & McLellan. Merz and McLellan had first worked together in Cork. His next major project was the Neptune Bank Power Station in Wallsend near Newcastle. It was the first three-phase electricity supply system in Great Britain, and was opened by Lord Kelvin on 18 June 1901. In the same year he toured the US and Canada. Together with Bernard Price, he developed and patented one of the earliest forms of automatic mains protection. This system was successful and became known as the Merz-Price system. When Price was succeeded by Philip Vassar Hunter, Merz worked with him to develop an improved version which became known as the Merz-Hunter system. He was known affectionately within the electricity industry as the "Grid King". He was a consultant to a local tramway company on the electrification of their horse-drawn routes and, subsequently, to the Tyneside local lines of the North Eastern Railway, a pioneer of British mainline railway electrification, whose electric systems were turned on in 1904. As well passenger commuter lines, these included a freight line using the ES1 electric locomotive. In 1905 he first attempted to influence Parliament to unify the variety of voltages and frequencies in the country's electricity supply industry, but it was not until World War I that Parliament began to take this idea seriously, then appointing him head of a Parliamentary Committee to address the problem. In the same war