Among the many uses of GRP, its role in the electrical infrastructure is one of the most widespread. GRP cable trays are a common sight in any kind of electrical installation today. GRP has virtually replaced all other type of conduits, including metal and plastic pipes that were previously used to carry wires and cables.
Today GRP offers us a long-term, durable, cost-effective and efficient solution. It is a product that is uniquely suited for the purpose of carrying cables and wires. Not only has it replaced the older materials like aluminium and steel, it also uses a new form — trays. The earlier conduits were pipes through which the cables would be laid out. Trays have obvious advantages of a better layout. The structure of GRP trays also makes it possible for to check the cables.
Types of GRP cable trays:
GRP cable trays can take many shapes and forms. The different shapes have their own advantages and each shape is chosen for a particular reason. Some may work better in certain environments, while some may work better with a certain type of cables.
Solid bottom tray
As the name suggests, these trays have a solid bottom. In fact, the tray completely encloses the cables on all sides. This is obviously one of the best ways of protecting the cable for corrosives or bad weather conditions. Weather conditions could include strong sun, wind or rain. Environments like a chemical factory or marine structures are also highly corrosive. The close bottom tray will protect the cables from harsh weather conditions, saltwater, chemicals or other corrosives.
But there are also certain disadvantages that come with a closed trays. Easy inspection are impossible because one must cut the tray to get access to the cables. This means that you have to take apart the tray and put a new one post inspection. Closed trays also accumulate dirt, damp and water. Closed trays can also result in heat build up where cables are packed closed together and are prone to heating. This is why only cables that do not heat are used in this kind of arrangement.
Ventilated trough tray
This gives us slightly more access than the closed trays. It has an opening at the bottom, through which the cables can be inserted or taken out. The opening allows for air circulation and water to drain. The trays are closed at the top because the closure stops objects or dust from falling inside.
Ladder cable trays
This type of cable gets its name from its ladder like structure. It has traverse bars placed at regular intervals, typically at a distance of 9 inches from each other. The traverse bars are designed to support the cable. The rungs of the ladder provide an anchor for the cables. The ladder structure means that the tray is a very open structure. It allows for the maximum possible air circulation. This makes it perfect for cables that are prone to overheating.
However, the open structure also means that the cables inside are exposed to weather conditions. To mitigate the effects of any corrosion, ladder GRP cable trays can come with one variation — some of them come with a cover. The cover can be taken off, giving us an easy access but covering the cables at the same time. The cover could be on one side or on both sides.
Wire mesh cable trays
The wire mesh trays offer one of the most open structure in GRP cable trays. Structured like wire mesh, the trays allows for maximum air flow from all sides. This allows the cables to stay cool. This kind of tray is ideal for cables that are prone to overheating. Wire mesh cable trays are used for telecommunication cable networks and low voltage fiber optic applications.
Trough cable tray
This type of tray is used when there are many cables. The trough provides a deep basin for the cables where more than the usual number of cables can be bunched together. This arrangement works best with cables that are not prone to heating.
Single rail cable tray
This type of GRP cable tray is similar to a ladder tray, except that the vertical bar runs through the center of the rungs. The bar provides anchor to the cables, while the evenly placed horizontal trays offer an open structure. This type of cable trays are most suitable for cables prone to overheating or in situations where we want quick access to the cables. It’s obvious disadvantage is that the open structure also makes the cable vulnerable to environmental corrosion.