Quick Hits

PART VI — EQUIPMENT GROUNDING AND EQUIPMENT GROUNDING CONDUCTORS

EPISODE 20 — Equipment Grounding When It's Required, Conductor Types & Sizing (270.109–270.124)

Slide 1 — Hook "Final stretch! Part VI covers WHEN equipment needs grounding, what conductor types count, and how they're sized — Parts VII, VIII, and IX wrap up the whole article after this."

Slide 2 — When fixed equipment needs an EGC (270.109–270.115)

• Fixed equipment needs a connection to an EGC if it's near ground/grounded metal (within 8 ft vertical / 5 ft horizontal and touchable), in a wet/damp location, in electrical contact with metal, in a hazardous location, or already fed by a wiring method that provides an EGC.

• SPECIFIC equipment that ALWAYS needs grounding regardless of voltage: switchgear frames, motor frames, motor controller enclosures, electric signs, skid-mounted equipment, motor-operated water pumps (including submersible), and metal well casings housing submersible pumps.

• Portable/mobile equipment systems: neutral grounded through an impedance, exposed metal parts connected to that grounding point, max 100V between the equipment frame and ground during a fault, continuous ground-fault detection that automatically de-energizes on fault OR loss of EGC continuity, and the grounding electrode must be isolated by 20+ ft from any other system's electrode.

Slide 3 — Types, ID & sizing (270.118–270.124)

• Permitted EGC types: wire-type copper/aluminum/copper-clad aluminum, RMC, IMC, EMT, qualifying Type MC cable, cable trays, cablebus framework, other listed continuous metal raceways/gutters.

• NOT permitted as EGCs: grounding electrode conductors (with a narrow dual-use exception), a building's structural metal frame, or tape/drain-wire cable shields on solidly grounded systems.

• Wire-type EGC identification: green, or green with yellow stripe(s) — 4 AWG+ needs identification at every accessible point if the insulation isn't already that color.

• Sizing: based on tables keyed to voltage class (1001-2000V, MV-90 2001-35000V, MV-105 2001-35000V) and circuit conductor size — never smaller than 6 AWG copper / 4 AWG aluminum if not part of a cable assembly.

• Separable connections (plugs/drawout gear) need first-make/last-break EGC continuity, and NO switch/cutout may ever be placed in the EGC path unless it disconnects all sources of energy.

Slide 4 — Quiz + CTA Q: "For portable/mobile equipment, the maximum voltage allowed between the equipment frame and ground during a ground fault is:" A) 50V B) 100V C) 150V D) 277V

✅ Answer: B — 270.115(C): 100 volts maximum.

CTA: 🎉 That's Part VI wrapped — and with it, the core technical heart of Article 270! Parts VII (connection methods), VIII (DC systems), and IX (instruments/meters/relays) are shorter, more specialized closing sections — follow for more daily quick-hit study notes as we finish out Article 270 next.

← View Chapter 2 Home

← Back To Article 270 Home

← Back To Quick Hits Home