Hydro-Electric Powerstation is a Grade II* listed building in the Gwynedd local planning authority area, Wales. First listed on 1 February 1996. Power station.

Hydro-Electric Powerstation

WRENN ID
hollow-quartz-moon
Grade
II*
Local Planning Authority
Gwynedd
Constituency
Dwyfor Meirionnydd MP: Liz Saville Roberts (PC)
Country
Wales
Date first listed
1 February 1996
Type
Power station
Address
Hydro-Electric Powerstation, Llechwedd Slate Mine, Ffestiniog
OS grid reference
SH 697 468
Coordinates
53.00334, -3.94302
Source
Cadw listing

Also on this page: flood risk · radon risk · weather exposure · detailed attributes ↓

Description

The Hydro-Electric Powerstation is a single-storey building constructed of slate with a slate roof, featuring half-hipped gables and deep verges and eaves. On the long side facing the railway, there are four large small-paned wooden cross-windows. The building includes a single-storey entrance porch with a boarded door and a half-hipped slated roof, along with weather-coursing at the intersection with the main block.

This powerstation remains almost entirely unaltered since it was built, with the original twin system of turbines and generators still in operation. The turbines were made by Gilbert Gilkes and Co. of Kendal and operate 175 kilowatt direct current Johnson and Philips generators at 385 revolutions per minute. It features General Electric switch gear with meters by Lionel Robinson and Co. of Thames Ditton. The building has an 8-bay roof supported by plain bolted king-post trusses and includes a contemporary 5-ton gantry crane.

Local climate

Hydro-Electric Powerstation sits in one of the wettest parts of the UK, with an average of 1,370 mm of rain a year. This makes it wetter than 96% of listed buildings in the UK. Its exposure to wind-driven rain is greater than that of 93% of listed buildings.

It experiences an average of 49 freeze-thaw cycles a year, more than 90% of listed buildings. Of these, 29 follow at least 1 mm of rain in the preceding 48 hours. Average temperatures at this location have risen by 0.3°C per decade since 1991.

Averages for 1991–2020; temperature trend 1991–2025. Figures describe the wider area (a grid cell of roughly 10 km), not the individual site. Contains modified Copernicus Climate Change Service information 2026.

More on this building

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