In August 1906, power from Cwm Dyli was used to power the Oakeley Quarry in Blaenau Ffestiniog carried over the Crimea Pass by a long overhead transmission line at 10,000 volts. It also supplied Dinorwic and Pen-yr-Orsedd quarries. Cwm Dyli was claimed to be the largest electricity generating plant of its kind in Great Britain at the time.
