High racking can reduce lighting levels by up to 50%. Therefore an empty space calculated for 300 lux will only achieve approximately 150 lux if high racks are installed with narrow aisles.

It is good practice to light narrow aisles with runs of narrow distribution fluorescent lighting arranged along the aisles to even out the vertical lighting levels from top to bottom of the racking, whilst giving enough light along the aisle. For mounting heights above 15m suitable discharge lamps may be used.