Hydro One says a failed lightning arrester caused a four-hour power failure on Saturday that affected Shelburne and three townships - Amaranth, Melancthon, and Southgate (including Dundalk and the former Proton Township).

The outage at about 4:40 p.m. affected about 4,660 homes and was described as a forced power interruption.

A spokesperson for Hydro One said a forced interruption occurs when a circuit fails unexpectedly and the problem on Saturday occurred because of a failed lightning arrester.

Power was restored to all customers by 8:15 p.m.