The distance from the wall for wallwashers should be at least one third of the room height. Alternatively, the wall offset is given by a 20 degree line extending from the base of the wall up to the ceiling. Whereas for normal room heights the luminaire spacing is the same as the wall offset, in high rooms this spacing must be reduced to compensate for the illuminance which is generally reduced. Wallwashers do not give optimum uniformity until at least three luminaires are used. A wallwasher in a room corner should be positioned on the 45° line.