Cable trays are often used on external walls and roofs, before cables enter the building through a roof penetration or vertical wall penetration – and effective weatherproofing of cable trays is critical to prevent wind or rainwater ingress. Rooftop installations are often subjected to harsh environmental conditions, including extreme temperatures, high winds, and exposure to UV. Cable tray systems are often used for cable management in commercial projects to support insulated electric cables on flat roofs. Traditionally, cable trays were often supported on concrete paving slabs or attached to trimmed down struts as a simple, speedy, cheap, support solution. They may also be found within ceilings and internal.