Electrical Conduit and Fittings

Electrical conduits and fittings are lengths of solid tubing used to house, protect, and cover electrical wiring and cables in power distribution systems. There are many standard conduit types. Flexible metal conduits (FMC) have a helically wound, circular raceway and are often used at the ends of rigid runs. Liquid tight flexible metal conduits (LFMC) have a sealed plastic covering over a flexible metal core. By contrast, liquid tight flexible nonmetallic conduits (LFNC) feature a liquid tight jacket over a flexible, nonmetallic core. Intermediate metal conduits (IMC) have rigid, circular raceways with thinner walls than rigid metal conduits (RMC). Galvanized rigid conduits (GRC) are made of metal and coated with zinc for increased resistance to abrasion and corrosion. Rigid nonmetallic conduits (RNC) are made of plastic and used in areas that are wet or corrosive. Nonmetallic underground conduits with connectors (NUCC) are somewhat flexible, corrosion-resistant devices with internal, factory-installed electrical conductors. Electrical metal tubing (EMT) conduits are relatively easy to bend, cut and form. Electrical nonmetallic tubing (ENT) conduits are circular and usually corrugated.

Electrical conduits and fittings differ in terms of shape and function. Both straight and angled products are commonly available. Adapters are used to connect two different types of pipes. Bulkhead fittings mount in walls or bulkheads and allow pipe connections on either side of the barrier. Caps cover the outside ends of pipes to dead-end the flow. Couplings are fittings that join two types of conduits. Elbows, sweeps, and bends permit an angled change in direction and often include a curve or radius. Expansion joints connect sections of pipe and allow movement caused by service loads, shock, or thermal cycles. Flanges fit onto conduit ends to provide mounting geometry. Goosenecks are inverted, J-shaped conduits for wiring lamps or exterior lighting. Nipples are short segments for joining two pieces, typically with male-threaded ends. Reducers with different sized ends are also available. Offsets are parallel, but unaligned conduits. Outlet boxes contain and protect electrical outlets at the ends of a run of wire or cable. Plugs are inserted into conduits to dead-end the run. Pull boxes are used where two runs meet. Pull elbows are similar to pull boxes, but have a removable plate or lid. Tees are three-port fittings shaped like the letter “T”. Wyes are three-port fittings shaped like the letter “Y”. U-returns are angled electrical conduits and fittings that reverse flow direction at 180°. 

Selecting electrical conduits and fittings requires an analysis of sizes, schedules, fitting ends, and features. Standard U.S. sizes range from ½” to 6”. Products that are measured in metric units such as centimeters (cm) are also available. For angled devices such as elbows and sweeps, radius is an important consideration. Schedule sizes are standards that define the inner diameter (ID), outer diameter (OD) and wall thickness. Some fitting ends use male or female pipe threads. Others use plain, flanged, or flared ends. In terms of features, some products provide magnetic shielding or are part of an integral coupling. Others have an architectural finish or are liquid tight. 

Electrical conduits and fittings are made from many different materials. Aluminum is a metallic element that provides good electrical and thermal conductivity, high reflectivity, and resistance to oxidation. Stainless steel is chemical and corrosion resistant and can have relatively high pressure ratings. Some aluminum and steel conduits and fittings are coated with polyvinyl chloride (PVC), a flexible polymeric material. Other products are galvanized with zinc or coated with urethane, a class of materials that exhibits good elongation, recovery, and toughness. Electrical conduits and fittings that are made from nylon, PVC, polyester, and polyethylene are also available.

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Part Numbers for Electrical Conduit and Fittings