They are especially useful in situations where changes to a wiring system are anticipated, since new cables can be installed by laying them in the tray, instead of pulling them through a pipe.
Ladder and ventilated trays may have solid covers to protect cables from falling objects, dust, and water.
Tray covers for use outdoors or in dusty locations may have a peaked shape to shed debris including dust, ice or snow.
[3] Large power cables laid in the tray may require support blocks to maintain spacing between conductors, to prevent overheating of the wires.
[7] Regular housecleaning is important for safety, as cable trays are often installed in hard to reach places.
This also applies to any silicone foam seals, but is easily remedied through the use of firestop mortars of sufficient compression strength and thickness, as shown above.
Also, some building codes mandate that penetrants such as cable trays are installed in such ways so as to avoid their contribution to the collapse of a firewall.