Cable trays have become an integral part of the modern electrical systems. The trays have a distinct advantage over the pipes that were used earlier as a conduit for electrical wires. Trays are more conducive to carrying wires because of their structure, especially where we have multiple strands of wires. The structure also makes it easier for changes to be carried out when compared to taking our wires from a pipe.
Cable trays can be of different kinds of material, including steel and aluminium. However, the most popularly used material is fibre-reinforced plastic or FRP. As a material for carrying electrical wires, FRP offers multiple benefits, putting it far ahead of other materials. FRP trays are now widely used in industrial and commercial installations where we are dealing with multiple bunches of wires. FRP is also used in pipe conduit systems.
What is FRP?
Fibre-reinforced plastic, also known as fibre-reinforced polymer is a composite material made from a polymer and fibres. The polymer is typically a thermosetting plastic, epoxy orvinyl ester. The fibres are of carbon, glass, basalt or aramid. It is made by a process known as step-growth polymerisation.
Here the plastic has been created by bonding other materials that are homogeneous, but have different physical properties. The result is a polymer that gives us the desired properties of both the components. The idea here is to counter the drawbacks of one component by injecting the property of the other component so that the sum is much larger than the parts.
In this case the plastic on its own is fairly weak, but tough. The fibre filaments give it strength and stiffness. The strength of this combination depends on the quality of both components, their proportion and even the pattern of the combination.
Type of FRP Cable Trays:
Solid-bottom tray: Solid-bottom trays completely enclose the cables, giving them full protection. But the tray has to be cut for carrying out any inspection or change. The covered construction also means that it is used in minimal heat generating cables. These trays are also vulnerable to moisture accumulation.
Ventilated trough tray: The ventilated trays, on the other hand have openings at the bottom. This allows for air circulation and water drainage. Cables can be inserted or taken out from any given point in the tray through the holes. The tray may have a cover on top to protect from falling objects or dust.
Ladder cable tray: The cables here get support from a traverse bar. This gives it an appearance that is similar to a ladder (hence, the name)! Like a ladder, the traverse bars are placed at regular and fixed intervals, usually 9 inches. The rungs of the ladder have their own function, providing an anchor for cables. Usually used without a cover, the ladder tray is best when there is a danger of cables overheating. The open structure will dissipate any heat.
Single rail cable tray: These FRP cable trays are typically used in case of low voltage cables. This type of tray works when quick installation and access to cables at any point of the tray is of priority.
Wire mesh cable tray: Lighter in weight, the wire mesh cable tray is used in low voltage fibre optic applications and telecommunication cable networks
Trough cable tray: This type of tray has a somewhat deep trough for cables, forming an enclosure
Benefits of using FRP for cable trays
Steel and aluminium are also used for cable trays. However, FRP has a distinct advantage over them — its ability to resist corrosion. FRP shows far greater resistance, able to withstand extreme conditions while staying intact. In addition, FRP is non-magnetic. Together these two properties lower the risk of electric shock from FRP trays.
FRP is also much lighter. This makes a significant difference when we are dealing with already heavy cable networks. Installation becomes much easier with less effort involved. This also brings down installation changes.
Conclusion
A composite of plastic and fibres, fibre-reinforced plastic or FRP finds wide usage in industrial areas. It forms an excellent conduit for electrical cables. FRP cable trays and pipes are often seen across the commercial and industrial landscape.
