subject: Types Of Metallic Conduit [print this page] Metal conduit is a kind of piping used by construction professionals to carry cables. Electricians also use them to enclose electrical wiring when building structures like homes, offices and stores. Read this article to learn more about the types of these metallic conduit.
Metal Conduit is piping or tubing designed to enclose the wires that circulate power in your home. Conduit piping has been in use since the early 1990s. Conduit piping is made up of different metals and comes in rigid and flexible forms. It is mostly used in homes for protecting outdoor and indoor wires or electrical cables. All Electricians use them to enclose or carry electrical cables when building structures like homes, offices and stores.
The Electrical Construction & Maintenance (EC&M) magazine says that in 2004 many companies shipped more than $2.2 billion of electrical conduit and fittings.
Types of Metallic Conducts:
Rigid Metallic Conduit:
It is a heavy duty variety of pipe mostly used in commercial applications (carry electric cables). They are available in - to 6-inch interior diameters. A galvanized version of this steel is used in wet and damp areas for underground applications. This galvanizing treatment prevents pipes from rusting and weakening from moisture damage.
Rigid metallic conduit includes:
1. Electrical metallic tubing (EMT), which is light-gauge pipe and easy to install. It is used for applications where the thicker rigid steel conduit is not required. It is also known as thin-walled conduit. Standard length of EMT is 10 feet and interior diameters are between to 4 inches.
2. Intermediate metallic conduit (IMC), which has a thicker galvanized wall and weight less than RMC. Its thicker wall makes it suitable for outdoor applications. Its large inside diameter permits easier wire-pulling.
3. Galvanized rigid conduit (GRC), it is thickest among all rigid metallic conduit and offers highest protection for the wires inside. GRC is expensive and requires threaded fittings. Its interior diameters are between 1/2 to 6 inches.
Flexible Metallic Conduit
It is made up of coiled or wound, interlocking and ribbed strips of metal such as steel or aluminum. It can bend and twist easily. It is used in the places where rigid conduit is difficult to install or connect. FMC conduit is available in 10 foot sections. A special power tool is required to cut this pipe. According to NEC regulations, FMC can be used as an electrical grounding tool.
Tips for Using Metallic Conduit
1. It is recommended to file off the rough edges to prevent damage to wires.
2. Metal electrical boxes must be used with metallic conduit.
3. Running a green grounding wire is recommended.
4. Use a large, heavy pencil instead of dry ink black marker when making marks on the conduit.
5. Always bend the pipe on the same plane when bending.
The most common types of residential conduit and their applications:
1. Electrical Metallic Tubing (EMT )
Benefits and considerations:
Light weight steel conduit and easy to install, can be bent and cut with the appropriate tools, more affordable than IMC and GRC.
Uses: Used most often in dry interior spaces, used in damp locations with corrosion-resistant hardware and rain-tight fittings.
2. Intermediate metallic conduit
Benefits and considerations: Thick, galvanized walls make it a good choice for exposed outdoor use, can also be used indoors, weight less than GRC so it's easy to work with it.
Uses: Approved for all interior applications, can be used outside.
3. Galvanized rigid conduit (GRC):
Benefits and considerations: Height level of protection, available in galvanized aluminum, steel and stain less steel, good for straight runways, threaded ends require threading fitting.
Uses: Approved for all interior applications, can be used outside.
