In the world of wire and cable (be it electrical, low voltage or else), conduits are used to conceal wires. More specifically, conduits are a tube or pipe, through which wires are routed. They come in a variety of shapes and forms, may be made of different materials, and are used for numerous applications.
While there are other ways to route wires, conduits make a good solution for concealing wires and protecting them from the elements, moisture, abrasion and chemicals for example. When properly sealed, conduits can keep fire out. When designed for it, they can be waterproofed, or encased in concrete. Metallic conduits shield wires from electromagnetic interference and allow for a fairly easy process of adding or removing wires as needed.
With all these benefits in mind, using conduits add a cost to the job; therefore it is advised to asses if these types of protections are needed. If cost is an issue and the protection of conduits is not needed, a more economical approach such as cable trays or support rings may be preferable. Something else to keep in mind is heat dissipation that may be an issue with fully enclosed conduits. This issue may arise when multiple cables are routed through the same tube, and may lead to a need to lower the current capacity of the conductors.
Non-Flexible Metal Conduit
There is a variety of non-flexible metal conduits. They are often made of steel, stainless steel or aluminum. As their name suggests, they are rigid and elbows are needed to allow for turning corners and making non straight paths.
RMC (Rigid Metal Conduit) and GRC (Galvanized Rigid Conduit) are thick walled and can be used indoors, outdoors, underground, concealed or exposed.
IMT (Intermediate Metal Conduit) is lighter than RMC, but heavier than EMT.
EMT (Electrical Metal Tubing) conduits are thin walled and therefore less costly than other thicker metal conduits.
Flexible Metallic Conduit
Flexible wire conduits are ribbed, to allow for bending and flexibility, which gives them a look of corrugated metal. It is important to note that they don’t stay bent permanently as PVC would. They are designed to eliminate the need for numerous fittings in a job where there are numerous turns.
Flexible Metallic Conduits (FMC) provide the protection of non-flexible metal conduits, with flexibility of a winding path. They also provide vibration isolation that is not available in a rigid conduit. If designed with a waterproof plastic coating, FMCs can provide waterproofing as well.
Non Metallic Flexible Conduit
Most non-metallic flexible conduits are made of PVC with a corrugated exterior. They are designed for a variety of applications, including communication cables, fiber optics, and more. They may be UV resistant for use outdoors, or rated for burial to use in soil. Non-metallic flexible conduits are typically water tights. Their resistance to corrosive and chemical depends on their design and rating.
PVC flexible conduits are used in riser applications, HVAC areas, water treatment systems and numerous other applications.
Before making a selection of the conduit type best suited for a job, first specify the types of wires being used, the environment and its elements and of course budget.