PVC Conduit

• Conduit made from PVC is light and inexpensive. Thinner grades are suitable for embedding in concrete, while electricians use conduit with thicker walls where the non-conductive and non-corroding properties of PVC are required. The conduit bends when heated, and electricians can use threaded fittings as well as glued slip-on fittings to avoid having to rotate the pipe. PVC conduit has a high coefficient of expansion and must be installed to allow for changes in length due to heating and cooling.
  
  

EMT Conduit

• Electric metallic tubing (EMT) conduit is a light, thin-walled steel conduit that can be bent onsite. Manufacturers usually apply a coating of zinc via electrogalvanizing to ensure a smooth surface that allows for easy cable pulling. EMT conduits are joined together and to equipment terminal boxes with clamped fittings. If installers have to use threaded fittings, converters with threads that clamp onto the EMT conduits are available.
  
  

Rigid Conduit

• Rigid conduit is hot-dipped galvanized steel and consists of thick-walled, heavy steel pipes that are threaded at either end. It is more expensive to purchase and more labor-intensive to install than other types of conduit but offers the highest mechanical protection in rugged environments. Fittings are threaded, and installers must use special fittings to allow them to rotate the pipes when necessary. Rigid conduit is required for certain applications by the National Electrical Code and other specifications.
  
  

Specialized Conduit

• Electricians use aluminum, stainless steel and polyethylene conduits for specific purposes where corrosion resistance is important or weight must be taken into consideration. Polyethylene conduit is less expensive than metal conduit, and its corrosion resistance makes it ideal for burial. Instead of conduit made from these materials, standard conduit coated with polyethylene is also available. Extremely corrosive and high-temperature environments require stainless steel installations. Nylon and polyester conduits offer superior flexibility but lower mechanical protection. Fiberglass conduits are used in environments where explosive material is present.