Cable trays are usually supported by all of the following means except?

Cable trays are designed to organize and support cables in various industrial and commercial environments. They are typically secured using components that can bear the weight and ensure stability over time. Metal brackets, wall mounts, and ceiling mounts are all standard methods used for supporting cable trays. They provide the necessary strength and stability to hold the trays securely in place, accommodating the weight of the cables they carry.

Utilizing #9 wire for supporting cable trays is not appropriate, as this type of wire is usually too flimsy to provide the necessary support. It is more suited for lighter-weight applications, such as securing smaller items or conducting electrical currents in low-load scenarios. Supporting heavy cable trays requires more robust materials and structures that can withstand not only the weight of the cables but also vibrations and potential impacts in an industrial environment. Therefore, cable trays should not be supported by #9 wire, making it the correct choice in this context.