CONDUIT BODIES AND COVERS
Conduit bodies are tubular hardware units with openings at each end to admit EMC conduit and cavities that are large enough to give the installer access to the ends of wires or cables so they can be pulled out and easily be redirected if necessary. These bodies are available in different sizes and are made to perform such functions as joining two sections of conduit to form either straight lengths or 90° bends.
below Figure illustrates six different conduit body styles and two different gasketed cover styles for body cavities, all with tables giving the dimensions of those styles for mating with standard conduit. Conduit bodies have threaded ports or openings for conduit and tapped holes for the screws to fasten the covers over the cavities to form watertight seals when wire or cable arrangement is complete.
Conduit bodies are especially useful for making right-angle bends in stiff, heavy conductor bundles or cable such as service entrance (SE) cable. For this reason they are widely used in making service entrance connections. Conduit bodies are standard commercial hardware items made from malleable iron or copper-free aluminum. The iron bodies can be galvanized or painted with enamel to prevent rusting.
Sections 314.5, 314.16, and 314.17 of NEC 2002, Article 314, “Outlet, Device, Pull, and Junction Boxes; Conduit Bodies; Fittings; and Manholes,” cover the installation and use of conduit bodies. The maximum number of conductors permitted (fill) in the conduit or tubing to which the bodies are attached is given in Chapter 9, Table 1, of NEC 2002. Conduit bodies must be durably and legibly marked with their volumes by the manufacturer to be approved for containing splices, taps, or other devices
CONDUIT CONNECTORS, COUPLINGS, AND FITTINGS
Many different kinds of connectors, couplings, and fittings are made for coupling or connecting similar or dissimilar lengths of conduit and making connections between conduit and various types of electrical boxes. They are made from materials such as zinc-plated steel, malleable iron, aluminum, die-cast zinc, and nylon. Conduit connectors and couplings are made in accordance with Underwriter’s Laboratories, Inc. (UL) standards and are also certified by the Canadian Standards Association (CSA). Connections can be made by set screws, compression methods, or screw-down clamps.
below Figure is a gallery of a representative illustrations of conduit connectors, couplings, and related fittings accompanied by short tables giving their dimensional data. Most of the connectors illustrated are for EMT conduit, but illustrations and tables are given for liquidtight straight and angled connectors, connectors for type B conduit, and connectors for flexible metal conduit and armored cable.
The dimensions given in the tables are based on information provided by several manufacturers and should be used for reference only. A complete directory of commercial conduit fittings is beyond the scope of this handbook. The reader is advised to consult the latest manufacturers’ catalogs for styles and dimensions of conduit hardware now being manufactured, because the product offerings are subject to change.