Electrical conduits refer to an electrical system used to protect and provide route of electrical wiring. Electrical conduits are made of metal, plastic, or fiber and could be rigid or flexible. Conduits must be installed by electricians following standard regulations, as those provided by the National Electrical Code (NEC). Here are the most common types of electrical conduits.
Conduits: Galvanized Rigid Conduit
A conduit made from galvanized steel tubing is commonly referred as a rigid conduit. The thickness of a galvanized rigid conduit protects the electrical wiring from being hit and allows it to be threaded. Galvanized rigid conduits are used by electricians in commercial and industrial applications.
Conduits: Electrical Metallic Tubing (EMT)
Another example of rigid electrical conduit is the EMT, also known as Electrical Metallic Tubing. An EMT conduit is made of steel; in some cases aluminum is also used, cheaper than a galvanized rigid conduit and lighter than a GR conduit. EMT is also a very popular material in commercial and industrial buildings because it can be bent to specific radius and directions. During the last couple of years EMT conduits have become popular in residential construction.
Electrical Nonmetallic Tubing
Electrical non-metallic tubing is another example of electrical conduit. A non-metallic conduit is thin-walled corrugated tubing, moisture-resistant and flame retardant. The non-metallic conduit can be bent by hand and can be easy installed due to its flexible properties. However, fitting used to connect non-metallic tubing are rigid and cannot be bent.
Flexible Metallic Conduit (MC)
A flexible metallic conduit forms a hollow tube in which electrical wires are passed. It is highly recommended in dry areas. The Flexible Metallic Conduit, also called Greenfield of flex, does not maintain permanent bend.
Liquid-tight Flexible Metal Conduit (LFMC)
A liquid-tight flexible metal conduit is covered by a plastic waterproof coating. Its interior is very similar with the flexible metallic conduit. It is recommended for use in general wiring, wet or damp locations. It can also be used to direct burial; concrete embedded, and site lighting jobs.
Rigid Metallic Conduit
The installation of Rigid Steel Conduit (RSC) is covered by Article 344 of the National Electrical Code® (NEC®). A rigid metallic conduit is made commonly from coated stainless steel or aluminum. The rigid metallic conduit can be treated to prevent corrosion by applying different coating to the conduit. Rigid steel conduit is the heaviest-weight and thickest wall conduit. Rigid metal conduit is available in trade sizes ½ through 6.
Liquid-tight Flexible Nonmetallic Conduit
Liquid-tight Flexible Nonmetallic Conduit (LNFC) is another term for a number of flame resistant types of non-metallic tubing. This type of tubing is recommended as a raceway for the installation of approved conductors with a nominal rating of 600 Volts or less for non-hazardous locations. The interiors of this conduit may be corrugated or smooth.
An aluminum conduit is a rigid conduit commonly used in commercial and industrial applications. Aluminum conduits are used to prevent corrosion and are the preferred conduit used in areas where large amounts of water and corrosion-prone areas. Aluminum cannot be directly embedded in concrete, since the metal reacts with the alkalis in cement. Aluminum conduits may be protected with additional coatings to prevent concrete is used in concrete slabs or walls.
PVC is the lightest conduit material and usually the lower cost conduit material. PVC conduits can vary in thickness depending on the uses and where the PVC will be installed. The PVC conduit resist moisture and corrosion but the tubing is non-conductive an extra grounding conductor must be passed into each conduit. PVC conduit has a higher thermal coefficient of expansion allowing the conduit to expand and contract. Be aware the installing PVC underground in multiple or parallel run configurations, mutual heating might cause problems on cable performance.