Until the mid-1960s the new Fastnet Lighthouse remained very much the same as when it was completed in 1904. There was no electricity at the station except for a small generator used to charge radio telephone batteries. The main navigational light was incandescent paraffin vapour with a power of 1,300,000 candelas. The fog-signal was tonite explosive charges. Cooking was by a coal-fired range and an oil stove, and domestic lighting was by oil lamps.
In 1962 the Board asked their Engineer to report on the provision of domestic electric lighting and the use of bottled gas for cooking. The Engineer, A.D.H. Martin, reported that the combination of paraffin for the main light, explosives for the fog-signal, and bottled gas for cooking was too dangerous to contemplate. He recommended the installation of electric lighting, heating, and cooking but not to change the main light from paraffin vapour. This proposal was approved by the Board and the expenditure involved was sanctioned by the Ministry of Transport in the 1963-4 estimates.
The original plan was to install two diesel powered alternators in the tower. Heating would be by storage heaters which would be charged when a generator was running. When the detailed design commenced, however, it was decided that a more efficient method of heating would be to use the waste heat from the water-cooled diesel engines.
An engine, alternator, heat exchanger, pumps, and dummy load were purchased and a full scale experiment was conducted in Dun Laoghaire to assess how much heat could be extracted from the cooling water of a Lister RW3 engine. The manufacturer of the heat exchanger requested, and received, the Board's approval to include a photograph of Fastnet Lighthouse in its annual report and accounts, with a caption announcing the proposed use of its equipment at the station.
When the results of the experiment were assessed it was decided not to use that particular heat exchanger but to provide engine cooling water coils within the tank storing the cooling water. The new plan entailed constructing a water storage tank in halves and erecting it around the central weight trunk. The two engines would be on the first floor and the tank would be on the floor above. The two half-tanks would be connected together and each half of the water tank would contain the cooling coil from one of the engines. The hot water from the engines passing through the coil would heat the water in the tank which would be circulated by a thermo-siphon through radiators to heat the tower in winter. In summer, when the radiators were not required, the heat would be dispersed through a fan-assisted radiator on the balcony to provide cooling for the engines.
An electric cooker would be installed in the Keepers' quarters but could only be used when the generator was running. Electric lighting would be from a battery which would be charged when the engine was running, so lighting would always be available. This would be a big advantage as some of the stores on the rock were pitch dark, even in daylight.
It was necessary to provide additional diesel oil storage tanks. In addition it was decided to install a water and oil pumping system, with pipelines from the boat landing cemented into chases cut in the rock. This would eliminate the need for water barrels landed from the ship to be carried from the landing and hoisted to the tower where they were emptied by hand into the water tank, and also eliminate hand pumping of oil.
The Board approved the new scheme and on 22 February 1967 the Secretary wrote to the Board of Trade seeking sanction to the revised estimate. The Board of Trade queried the proposal saying they thought the heating system would not be efficient enough-as the generators would only be run at night, and the system could not store up enough hot water to heat the tower throughout the day, they were afraid the Keepers would run the generators during the daytime after the heating system cooled down. They asked the Commissioners to consider the original plan of using storage heaters.
The Secretary replied by return, saying that the Board of Trade's technical officers' suggestion was understandable as it was appreciated that it was difficult for them to understand the situation at Fastnet. The letter, which was drafted by the Electrical Engineer (later Engineer-in-Chief) N. D. Clotworthy, went on patiently to explain that it was necessary to cool the engines anyway, and the only way to do this was by radiators. Air cooled engines were ruled out as it would mean cutting large air-ducts through the magnificent stone work of the tower, which would also lead to the possibility of sea water entering and flooding the tower. Space in the accommod-ation at Fastnet was limited. Storage heaters were much more bulky than radiators and also the heat from them could not be controlled unless special fan-blown units were obtained. Storage heaters could produce too much heat and ventilating the tower in bad weather was always a problem.
Using the results of the experiment in Dun Laoghaire, the letter went on to demonstrate that producing electricity for the storage heaters would use an extra 4.8 gallons of diesel oil a day and additional oil storage tanks would be required.
A fortnight later the Board of Trade gave in and sanctioned the revised estimate.
The equipment was ordered from the various suppliers and the work of installing the electric heating, lighting, and cooking proceeded. On 7 August 1968 the Engineer, now re-graded Engineer-in-Chief, reported to the Board that the work was well advanced. However, to make use of the weight trunk running down the centre of the tower as an air inlet duct for the engines the clockwork optic drive had been replaced by a duplicate electric drive. The Engineer-in-Chief expressed concern about the proximity of the electric drive motors to the paraffin vapour light and the fire hazard present by the five 130 gallon paraffin tanks on the floor above the generators.
The Board accepted the Engineer-in-Chief's recommendation that the main navigation light be converted to electric, thus dispensing with paraffin oil. The Board also approved the fitting of a fireproof door between the 2nd and 3rd floors and the installation of a total flood fire extinguishing system to flood the three lower floors in the event of fire.
To cover the failure of one generator while the other was being overhauled, a third generator would be required, smaller than the others but of sufficient capacity to operate the main light in an emergency. Once again the Secretary wrote to the Board of Trade, which sanctioned the electrification of the light but asked the Commissioners to consider BCF instead of carbon dioxide for the fire extinguishing system. The Commissioners considered the Board of Trade's suggestion and approved the installation of BCF.
BCF is bromo-chloro-difluoro-methane, also known as halon. At that time it was considered safer than carbon dioxide but it is now recognised as a major cause of ozone depletion in the upper atmosphere, and more recently its use has been discontinued at all Irish Lights stations.
Electrification of the main light went ahead and the new light was put into operation on 10 May 1969. The electric light had the same character as the paraffin vapour light-one flash every 5 seconds-but the flash was of a shorter duration and greater intensity-2,500,000 candelas, having a luminous range of 28 nautical miles.
As part of the modernisation of the lighthouse some of the rooms were re-arranged, and new specially designed bunks and other furniture, made in the workshops in Dun Laoghaire, were installed. The total cost of the modernisation was £13,241, excluding the electrification of the main light which cost £4,264.
In 1971 it was found that more diesel oil than expected was being consumed, and two additional storage tank sections were installed bringing the total capacity to 9,300 gallons.
In the early 1970s the storage of explosive charges and detonators for fog-signals at lighthouses became a security issue and the Commissioners decided to discontinue explosive fog-signals. The explosive fog-signal on Fastnet was replaced by an electric horn in 1974.

Automation
Following the Commissioners' annual tour of inspection in 1978 it was proposed that the automation of Fastnet Lighthouse should be included in the development programme for the Service. At that time it was envisaged that a limited number of lighthouses at strategic locations would continue to be watched by Lightkeepers. As time went on the automation of all lighthouses around the coast became inevitable, however, and a plan was developed to achieve this objective within an agreed timescale.
The work of automating Fastnet Lighthouse began in mid-1988 and continued into the early part of 1989. The original biform optic was retained, rotated by a gearless optic drive instead of the rotation motors installed in 1969. The lamp was changed to a one kilowatt metal halide lamp with a lamp changer which automatically brings a spare lamp into service if the first lamp fails. In addition, two 300mm emergency lanterns with a range of 6 nautical miles were fitted on the upper balcony rail, designed to switch on automatically should the main light fail.
The generator plant was replaced by new equipment. Automatic control systems were installed for the light, and to control the fog-signal, generators, automatic water cooling, fuel management, fire protection, and security systems.
In addition, all the electrical services in the tower were renewed. A remote control and monitoring system linking Fastnet by uhf radio to a base station at Mizen Head, and from there by telephone line to the central monitoring room in Dun Laoghaire was also installed. Every six hours this system checks the status of the equipment at the station. In the event of any equipment failure the system immediately communicates an alarm signal through Mizen Head to the Telemetry and Security Officer at Dun Laoghaire. The system incorporates facilities for remotely commanding equipment on or off from either Mizen Head or Dun Laoghaire.
The limited living accommodation and cramped working conditions necessitated a high degree of organisation and planning during the installation of the new systems.
On completion of the installations the Keepers were withdrawn and the lighthouse became unwatched from 5 April 1989.
Following the visit to the station of the Commissioners' Inspecting Committee later that year Capt. A. C. Tupper, Inspecting Committee Chairman, reported-
'The Committee was particularly pleased to note the high standard of workmanship achieved in the automation of the Fastnet Lighthouse where space limitations and other restrictions made work of high quality extremely difficult.'