Strut, What Fits

1. What is strut channel and why is it used?

Strut channel is a standardized metal framing system used to support conduit, cable tray, mechanical piping, and equipment. It allows modular assembly using slotted or solid steel profiles, with pre-engineered fittings that eliminate welding or drilling.

2. Where is strut channel typically used?

Strut is deployed in commercial, industrial, and institutional settings—supporting conduit, cable tray, HVAC piping, lighting, and equipment racks. It’s common in data centers, hospitals, schools, and utility plants. Outdoor use demands hot-dip galvanized or stainless finishes; food-grade zones require stainless with sealed fittings.

3. What are the standard strut sizes and profiles?

Common profiles include 1-5/8" x 1-5/8" (deep channel), 1-5/8" x 13/16" (shallow channel), and 1-1/2" x 3/4" (mini strut). Profiles may be solid, slotted, or punched. Depth and gauge affect load rating, compatibility, and fitting selection.

4. What finishes are available—and when do they fail?

Typical finishes include pre-galvanized, hot-dip galvanized, powder-coated, and stainless steel. Pre-galvanized fails in outdoor or corrosive environments. Hot-dip is preferred for exterior use. Stainless is required in food-grade or chemical zones. Powder coating adds color but not corrosion resistance.

5. What fittings work with strut channel?

Fittings include angle brackets, T-connectors, U-bolts, beam clamps, spring nuts, rod couplers, box brackets, tray supports, seismic braces, and grounding lugs. Compatibility depends on profile depth, slot pattern, gauge, and torque discipline. Always match fitting type to strut geometry and system load.

6. What causes misalignment in strut assemblies?

Misalignment stems from mixing incompatible profiles, mismatched slot patterns, gauge variation across brands, improper fitting orientation, and under-torqued fasteners. Field failures often trace back to skipped anchoring, asymmetrical brackets, or assuming interchangeability. Always verify profile, finish, and hardware spec before install.

7. How do you attach hardware and conduit to strut?

Strut supports a wide range of hardware—bridle rings, threaded rod, conduit, and boxes—using modular fittings and slot-compatible fasteners.

• Bridle rings: Use spring nuts, channel nuts, or adapter plates to seat bridle rings securely in the strut slot. Verify thread type and load rating. For cable separation, stagger rings by signal type and maintain vertical clearance.
• Threaded rod: Attach using rod couplers, beam clamps, or strut inserts. Match thread size and torque to load requirements. Brace vertical runs as needed.
• Conduit: Secure with strut clamps, U-bolts, or cushion clamps sized to conduit OD. NEC spacing rules apply—typically 10 feet for horizontal runs.
• Boxes: Mount using box brackets, offset plates, or custom strut assemblies. Ensure box depth matches strut profile and mounting hardware clears conduit entry.

8. What’s the rule on conduit and cable tray support?

Strut must be sized for load and span. NEC and NEMA standards dictate spacing—typically 10 feet for conduit, 5 feet for cable tray. Use spring nuts or channel brackets rated for the load. Never rely on friction or undersized fasteners.

9. What causes strut failure in the field?

Top failure modes include overloading, corrosion, improper anchoring, and thermal expansion stress. Field audits often reveal missing bracing, unsupported spans, or incompatible materials. Always verify finish, gauge, and torque specs.

10. What are common installation errors to avoid?

Top errors include mixing incompatible profiles, under-torquing fittings, skipping anchoring, and overloading spans. Misaligned slots or mismatched hardware lead to stress fractures and field failures. Never assume interchangeability across brands.

11. Can strut be used for seismic or wind bracing?

Yes—with proper engineering. Use heavy-gauge profiles, seismic-rated fittings, and anchoring systems that meet ASCE 7 and IBC requirements. Bracing must be calculated for lateral loads, drift limits, and anchorage pullout strength.

12. What hardware uses strut as its infrastructure?

Strut serves as the backbone for mounting electrical boxes, conduit, threaded rod, cable tray, bridle rings, lighting fixtures, HVAC components, equipment racks, signage, and enclosures. It provides alignment, spacing, and modular support across ceiling grids, walls, and mechanical zones.

13. How do you label and document strut assemblies?

Label by zone, load type, and system supported—e.g., “Zone 3: Cable Tray Support, 150 lb/ft.” Documentation should include profile, finish, fitting type, torque spec, and anchoring method. This supports inspection, maintenance, and MAC workflows.

14. What’s next for strut channel systems?

Expect tighter integration with BIM, pre-assembled kits, and smart labeling. Some systems now include QR-coded fittings, torque indicators, and modular seismic kits. The future is engineered, auditable, and field-ready.