Knightshayes Court Devon
Hydro-electric Power Generation


Hidden away and forgotten about for well over half a century is an example of early 20th century electrical history, that of hydro-electric power generation. Inside this small building can be found the equipment of a hydro-electric generating plant.

The property Knightshayes Court was built as the home of the Heathcoat Amory family between 1869 and 1874. Later, most probably around the end of the 19th century the family must have decided to adopt the luxury of electricity, using this new technology which could be used to light the rooms in the house. To generate the power to create this electricity, water was taken and diverted from the adjacent River Exe and harnessed to drive a water turbine. This new form of lighting must have been a dramatic improvement upon the earlier lighting provided by oil lamps. There is no evidence within the property that a gas service was ever installed.

Turbine Building

The building measures approx 10 metres x 5 metres with a floor to ridge height of 10 metres. The basement of the building was constructed as a reservoir to store the water needed to power the turbine. Sluice valves were installed to isolate the water supply and allow for maintenance of the equipment. A new water-course was constructed to divert water from the River Exe to the turbine building.

One end of the building houses the water turbine which is submerged within the reservoir, and through a vertical drive shaft, pulley and belts drove a dynamo which originally generated electrical power at approx. 110 volts DC.

At the same end of the building adjacent to the vertical drive shaft is a second vertical drive shaft fitted with a bevelled gear.

The top section of the bevelled gear was connected to a horizontal drive shaft which powered equipment housed in an outside lean-to building. As this top gear section and drive shaft have been removed, its purpose will never be fully known. A reasonable assumption would be that it powered farm machinery.

Distribution Cabling

From the DC dynamo the electrical cables were then routed through a buried cast iron pipe across the adjacent fields to Knightshayes Court, approx ¾ of a mile away.

As DC cables generate heat, a means of dissipating this heat was needed. So an interesting feature of this buried pipe is that it was filled with oil presumably to act as a heat conductor removing much of the heat generated by the cables. The oil filling equipment for the cast iron pipe is still installed within the turbine building and carries the inscription,
Johnson & Phillips
Brookes Patent Liquid System
Underground Mains
Sole Makers
Engineers   London

To store the DC electric current for the periods when lighting was not required batteries / accumulators were provided. A room at the rear of the courtyard was used to house the batteries / accumulators.

The only examples of the original DC wiring installation inside the
house are to be found in the attic area above the servants quarters.

Updating the Equipment

At a later date most probably during the 1940’s the DC dynamo was removed and replaced by an alternator/generator manufactured by Brook Motors Ltd of Huddersfield providing power most likely at 415 volts 3 phase 50 hz AC. This alternator/generator complete with its drive belts and switchgear is still installed within the building.

The original DC cable network was then abandoned and new AC cabling installed which was routed from the turbine building as overhead cables fixed to poles. Any electrical current surplus to requirements could be fed into the National Grid. Meters were installed to measure the amount of electrical current used.

Dating the Equipment

The establishment of dates when the turbine building was constructed and its original DC generating equipment installed has proved to be difficult, as no written records appear to still exist. An Ordnance Survey map of 1888 does not show the turbine building. It is known that during the 1930’s DC electric lighting was still used in the house and that during the 1940’s conversion to AC had taken place.

Further investigation will be needed to search for any written records.

Future Preservation

BUILDING. - Partial restoration of the building, has already been carried out by the Landowner, by the removal of the vegetation that had completely obscured the structure. Also on one side of the building the pitched roof sheeting has been replaced to prevent any further rain water penetration.

EQUIPMENT. - The opportunity now exists for this building and its electrical equipment to be conserved and preserved. Whilst it is obviously not possible for the equipment to be reused it could be cleaned and preserved for display purposes, to show historians how a small hydro-electric power plant was used to provide lighting for the country house, especially those who were lucky enough to have a large river within close proximity of the property.

RESERVOIR. - The possibility of emptying the building's water reservoir should also be considered, by pumping the contents into the downstream water course. This action would allow the water turbine and its drive mechanism to be viewed, recorded and studied.

This photo of the turbine building was taken when it was almost completely covered by vegetation and before any restoration work was carried out.  In a perverse way it is due to its parlous condition coupled with its remoteness of location, that has kept it free from vandalism.

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