Montreal's landmark electric cross on Mount Royal will be turned off Friday to allow for renovations.

The 83-year-old cross will be repainted and outfitted with a new energy-efficient lighting system, which will include polychromatic bulbs to allow a greater variety of colours.

Makeover costs are expected to total $982,138, Plateau Mont Royal borough Mayor Helen Fotopoulos said.

The 31.4-metre cross was installed in 1924 and normally glows white, but turns purple as a sign of mourning when the pope dies.

The cross last glowed purple in April 2005 when Pope John Paul II died.