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Cof Cymru: National Historic Assets of Wales · Wales

Transformer House

Llanllyfni, Gwynedd, Wales

The record

Designation
Listed building, Grade II
Broad class
Industrial
Date of designation
21 July 2000
Locality
Pen-yr-Orsedd
Town
Caernarfon
Community
Llanllyfni
Unitary authority
Gwynedd
Country
Wales
Coordinates
53.06400, -4.22505
Cadw reference
23672

Slide toward Today to fade the historical sheet and see the modern map underneath.

David Rumsey Map Collection, Stanford Libraries

Shown on 5 historical map sheets, the earliest the 1795 "To Sir Watkin Williams-Wynn Bart ... the map of the six counties of North Wales is most humbly inscribed by his obedient humble servant" (Llyfrgell Genedlaethol Cymru – The National Library of Wales).

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This record in Cadw's own full report ↗

Cadw's description

Located on Level VIII (Bonc Brig) of the Pen-yr-Orsedd Slate Quarry towards the foot of the modern steep access road from Y Fron.

Built in 1906 for the first supply of electricity to the quarry from Cwm Dyli power station, itself opened that year and pioneering in Britain for the being the first to use alternating current. The quarry opened c1816 and in 1863 it was bought by W A Darbishire & Co. During the 1890s about 450 men worked here: it finally closed in 1997.

Regularly coursed slate slabs; slate roof with 2 transverse gables to the gable ends, that to the front (north-west) larger. Wall below has 2 rectangular window openings (boarded at time of survey); tall doorway with boarded double doors to side (north-east) wall.

Access not available at time of Survey.

Included as a well-preserved transformer house built to provide the first remote-generated electricity supply to the quarry in 1906, a pioneering development at this time.

Nearby in the register

Other entries of the same register within about three miles of this one, by straight line.

Designated Historic Asset GIS Data, The Welsh Historic Environment Service (Cadw), 2026-09-07, licensed under the Open Government Licence http://www.nationalarchives.gov.uk/doc/open-government-licence/version/3/ Cadw, the Welsh Historic Environment Service · Open Government Licence v3.0
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