Inisheer Lighthouse was completed in 1857 after it was argued that the Inishmore lighthouse was too high and it did not cover the entrances to the North or South Sounds of the Islands.
The lighthouse originally had a fixed optic lamp which was supplied by the Chance Brothers of Birmingham. In 1913, the light was then converted to an incandescent with a paraffin vapour burner with a sequence change from fixed to occulting i.e. 10 seconds of light, 10 seconds of darkness (now called isophase).
The light was once more converted to an automated unwatched electric light with three diesel generator sets and a backup battery in case of complete electric breakdown.