Support of Steel Conduit / Tubing
Follow all Code requirements for spacing of supports and frequency of securing RMC, IMC and EMT. The requirement to securely fasten raceways within the specified distance from each “termination point” includes, but is not limited to, outlet and junction boxes, device boxes, cabinets, and conduit bodies. Each raceway shall be so secured. Do not omit any supports.
NOTE: Proper support and secure fastening protects the raceway joint during maintenance in the area of the raceway; this will help ensure a continuous ground path. Good workmanship in this area improves safety for the installer, other workers and the public.
Securing and fastening
Raceways are permitted to be mounted directly to the building structure. Ensure that supporting means and their associated fasteners are compatible with the mounting surface from which they are supported. Raceway supports shall be installed only on conduit of the trade size indicated on the fitting or its smallest unit shipping container.
The following supporting and fastening methods are recommended (also see 4.3.4 “Note”):
- Steel conduit / tubing exposed on masonry surfaces, plaster, drywall or wood framing members: One-hole straps, two-hole straps, conduit hangers, or similar products intended for the purpose, securely fastened with appropriate hardware. Conduit or tubing in trade sizes 1/2 through 1 are permitted to be supported by nail-straps in wood framing members.
- Steel conduit / tubing mounted on metal framing members: One-hole straps, two-hole straps, conduit hangers or similar products intended for the purpose, fastened with metal screws or rivets. When using clamp-on supports, add screws, rivets, beam clamps, or similar means for extra support, unless the clamp-on supports are the hammer-on or press-on type.
- Steel conduit / tubing run through openings in metal or wood studs: Such openings can be used for support where the openings are no more than 10 feet apart. Secure fastening at termination points is still required. Be sure to secure the conduit or tubing to the framing member where the raceway transitions to vertical and within three feet of the termination, as required by the NEC®.
- Steel conduit / tubing suspended below ceilings or structural members such as beams, columns, or purlins, or in ceiling cavities: These raceways are best supported by lay-in pipe hangers. The pipe hangers are to be supported by threaded rod, which is, in turn, fastened in place by beam clamps or similar devices. Strut-type channel can also provide secure support. Raceways are not permitted to lie on the suspended ceiling. In fire-rated ceiling cavities, support by the ceiling wires is not permitted unless tested as part of the fire-rated assembly. A separate support system must be installed for the conduit / tubing. Where this system is wire, it shall be identified as the raceway support. Conduit / tubing support wires must be secured at both ends. In non-fire-rated ceiling cavities, the ceiling wires can be used for support where installed in accordance with the manufacturer’s instructions.
- Groups of conduit / tubing: Mount on strut-type channels, and secure in place with strut-type channel straps identified for the particular channel and raceways. Channel shall be fastened in place by means suitable to the mounting surface.
- Support at new concrete pours: In these cases, place approved channel inserts into the concrete pour. Raceways will be mounted to the channels later in the construction process.
- Structural steel members: Where raceways are mounted inside the web of I-beams, column-mount supports are permitted to support the conduit.