EMT Support Spacing and Fastening: NEC 358.30, Straps, Hangers, and Strut Clamps
Sep 03, 2026
Support is the most-cited EMT violation because it is the easiest to see. The rule is short; the hardware choices are where people go wrong. Products: EMT Straps & Hangers.
The rule — NEC 358.30
- Within 3 ft (900 mm) of every outlet box, junction box, device box, cabinet, conduit body, or other termination.
- Every 10 ft (3 m) along the run.
- Exception 1: where structural members don't allow 3 ft, unbroken lengths may be fastened up to 5 ft from the termination.
- Exception 2: horizontal runs through framing members that are supported by the framing itself count as supported, provided the 3-ft rule at terminations is met.
- Concealed EMT in finished ceilings and walls still needs support — it cannot rest on ceiling tiles or grid wires (300.11).
- Rigid (RMC, Article 344.30) and IMC (342.30): also 3 ft from terminations, but interval scales with size — 10 ft for 1/2"–3/4", 12 ft for 1", 14 ft for 1-1/4"–1-1/2", 16 ft for 2"–2-1/2", 20 ft for 3" and larger.
Choosing the hardware
| Support | Use it when | Notes |
|---|---|---|
| One-hole strap (EMT) | Runs on walls, ceilings, and framing; the default | Sized to EMT OD — do not use a rigid strap on EMT, it will be loose. Electro-galvanized steel indoors; stainless or hot-dip in corrosive/outdoor. |
| One-hole strap (rigid) | RMC / IMC runs | Larger ID for pipe OD; malleable iron for heavy sizes and where straps get stepped on. |
| Two-hole strap | Where the strap is the only thing holding a heavy or vertical run, or on block/concrete | Two anchors resist rotation; required by many specs for 1-1/2" and up. |
| Conduit hanger with bolt | Suspended runs on all-thread from the deck or from strut | Hanger clamps the tube; bolt to 1/4"-20 or 3/8" rod. Keep the rod plumb. |
| Strut clamp (EMT/rigid) | Runs on channel strut, trapezes, and racks | Sized to tube OD; the bolt-and-nut clamp bites the strut lip. Multi-run racks go here. |
| Midget / small-diameter strap | 1/4"–3/8" flex, small tubing, low-voltage | Not for EMT. |
Fasteners
Wood: #8 or #10 wood screws, 1-1/4" minimum. Steel stud: self-drilling screws. Concrete/block: 1/4" sleeve or wedge anchors for one-hole straps, two anchors for two-hole. Never rely on drywall alone. Straps are not a listed bonding means — they don't replace grounding bushings or bonding jumpers.
Vertical runs
Support at the top and at intervals per 358.30; use two-hole straps or clamps that grip, since one-hole straps on a vertical run carry the load in shear. Long vertical risers in shafts use riser clamps at each floor (300.19 applies to conductor support, separately).
Fitting selection and NEC 358 basics: EMT Fittings Guide.
