Quick Hits

EPISODE 19 — Bonding Other Enclosures Loosely Jointed Raceways Hazardous Locations and Piping or Structural Metal (270.96–270.106)

Slide 1 — Hook "A dense episode — bonding continuity for non-service equipment, hazardous locations, and the big one: bonding water pipes and structural steel."

Slide 2 — 270.96–270.100

• 270.96: Metal raceways/cable trays/armor/enclosures serving as EGCs must be bonded for continuity and fault-current capacity — nonconductive coatings removed at contact points, or use fittings that don't require removal.

• 270.97: Non-service raceways/cable sheaths need the same bonding methods as services (minus the "bond to grounded conductor" option), with extra allowances for threadless couplings, double locknuts, shouldered fittings, or listed fittings when knockouts aren't oversized.

• 270.98: Expansion/deflection fittings and telescoping raceway sections need bonding jumpers or other means to stay electrically continuous.

• 270.100: In hazardous (classified) locations, bonding continuity is REQUIRED regardless of system voltage — using the same reliable methods as 270.92(B)(2)-(4), whether or not a wire-type EGC is also present.

Slide 3 — 270.104 & 270.106 — piping & structural metal

• Metal water piping systems must be bonded to the service enclosure, grounded conductor, GEC, or grounding electrode(s) — sized per Table 270.102(C)(1), capped at 3/0 copper / 350 kcmil aluminum. Multi-occupancy buildings with isolated piping can bond to their own panelboard's EGC terminal instead.

• Other metal piping likely to become energized (including gas piping) needs similar bonding — but NEVER to metal gas piping as the grounding electrode itself, and connection points must stay accessible.

• Exposed structural building steel that's interconnected and could become energized needs bonding too, same general sizing cap.

• Separately derived systems need their OWN bonding to nearby water piping and structural steel in their service area.

• 270.106: lightning protection system ground terminals must be bonded to the building's grounding electrode system.

Slide 4 — Quiz + CTA Q: "In a hazardous (classified) location, is bonding continuity required regardless of the electrical system's voltage?" A) No, only for systems over 1000V B) Yes — required regardless of voltage C) Only if a wire-type EGC is present D) Only in Class I locations

✅ Answer: B — 270.100: bonding continuity in hazardous locations is required "regardless of the voltage of the electrical system."

CTA: Follow for more daily quick-hit study notes 📚⚡ — Part V complete! Part VI (Equipment Grounding) is next.

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