Electrical Conduit
An electrical conduit is a tube in which electrical wires are housed for a variety of building or structural applications. Conduit protects wires as well as any individuals who may come into close proximity to the wires. The US National Electrical Code (NEC), and local building codes, determine whether or not a conduit should be used in a certain installation as well as which type of conduit should be used.
Failure to take proper precautions when working with electrical components can result in serious injury or death. Follow the manufacturer's instructions for all tools and wear appropriate safety gear. Check to see if you need a permit. Observe applicable building and electrical codes. Contact a licensed electrician if you have any doubts or questions about the connections or if your home's wiring doesn't appear compatible with the changes you're making.
Rigid Metal Conduit
Rigid metal conduit (RMC) has a thick wall and is constructed of either aluminum or galvanized steel. This variety is one of the most heavy-duty types of conduit used in many industrial applications. Rigid metal is one of the more costly options but offers additional strength.
Galvanized Rigid Conduit
Galvanized rigid conduit (GRC) has the thickest walls of all electrical conduit and is the heaviest. GRC is regarded by electricians for its superior corrosion resistance, and it protects wiring from electromagnetic interference (EMI). GRC can be used in outdoor or indoor applications and can be exposed, concealed and buried.
Intermediate Metal Conduit
Intermediate metal conduit (IMC) is a type of a rigid conduit rated for outdoor exposure and is intended for protecting insulated electrical cables and conductors. It offers much of the same protection of rigid metal conduit but is a more economical option for projects where cost is an issue.
PVC Conduit
Polyvinyl chloride (PVC) conduit is the most popular type of non-metallic conduit and has several advantages:
- Versatile and easy to install
- Typically less expensive that other options
- Lightweight
- Available in a variety of wall thicknesses
- Works well in concrete and underground
Despite its many advantages in other applications, PVC conduit isn't recommended for use in areas with direct sunlight exposure. Sunlight can break down the material over time.
Liquid-Tight Non-Metallic Conduit
Liquid-tight non-metallic conduit is designed for use in environments where moisture could become an issue. This type of conduit must be used in conjunction with liquid-tight fittings.
Electrical Metallic Tubing
Electrical metallic tubing (EMT) is made from coated steel or aluminum and is a more economical and thinner-walled option than other conduit. This conduit type doesn’t offer the same protection as rigid metal conduit but is lighter and can be paired with conduit fittings, eliminating the need for threading. EMT can also be bent to shape using a special tool to fit around obstructions or follow the shape of the installation.
How to Bend Conduit
Electrical metallic tubing can be bent with a special conduit bender tool to accommodate a variety of electrical applications. Measure the installation area to determine the angle and length of conduit you need. You’ll also need to calculate the necessary deduct length or takeup, which is the amount of extra length that'll be lost in the bend. This length will vary depending on the diameter of the conduit you’re using, but many conduit benders have guide marks to help you calculate. After you’ve determined the correct deduct length, mark where the bend should go and make any necessary cuts on the end. Use a conduit reamer or other tool to remove any burrs at the end of the conduit. When bending a piece of conduit, keep pressing firmly on the heel of the conduit bender with your foot and pull back on the handle with steady pressure to keep the tool from slipping.
Always follow the manufacturer’s safety instruction for any conduit tools.