The beacons were lighted on 1st May 1913 using acetylene made in a water to carbide generator close to the lower front mark. Whilst they were unwatched the Keeper ashore from either Skelligs or Inishtearaght, living at the Knightstown dwellings cleaned and charged the generator periodically.
When the front light was converted to an electric direction light on 16th August 1967 the rear light mark was discontinued, however this was re-established on 9th March 1977.
The front light is on a white conical tower with a red stripe. Its character is Oc WRG 4s, the ranges as follows: White: 11 nm, Red: 8 nm, Green: 8 nm; and sectored as follows: Green 134° - 140° (6°), White 40° - 142° (2°), Red 142v - 148° (6°).
The rear light is a red stripe on a white wall, 122m from the front lead. Its character is Oc W 4 secs visible from 133° - 223° (90°) with a range of 5 nm, synchronised with the front lead.
On 26 February 2011 a new directional light was established in the same position as the old front lead with a character of Dir Oc. W R G 4s (3.0 + 1.0) and sectored as follows: Green 136° -140° (4° ), White 140° -142° (2° ), Red 142° -146° (4° ). The light is shown 24 hours a day. The night time range remains the same as the previous front light. The day time ranges are White 3 nm, Red 2nm, and Green 2nm.