Quick Hits
Quick Hits
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EPISODE 4 — Marking Requirements — Part I Finale (310.8)
EPISODE 4 — Marking Requirements — Part I Finale (310.8)
Slide 1 — Hook "Closing out Part I — every piece of information that has to be printed on a conductor or cable, and how it actually gets marked."
Slide 2 — 310.8(A) & (B) — what's required, and how
Required info on every conductor/cable: maximum rated voltage, the type letter(s), the manufacturer's identifying mark, the AWG size or circular mil area, and — if a cable's neutral is smaller than its ungrounded conductors — a marking noting that.
Surface marking (durable, on the conductor/cable surface): applies to single/multiconductor thermoset/thermoplastic wire, NM cable, SE cable, UF cable, tray cable, irrigation cable, power-limited tray cable, and instrumentation tray cable. Size markings repeat at least every 24"; other markings repeat at least every 40".
Marker tape: metal-covered multiconductor cables need an internal marker tape running the full length (MI and AC cable are exempt; MC/ITC/PLTC cable can instead mark the outer nonmetallic covering directly, at 40" intervals).
Tag marking: MI cable, switchboard wires, metal-covered single-conductor cables, and AC cable get a printed tag on the coil/reel/carton instead.
Slide 3 — 310.8(C) & (D)
Suffixes for conductor count: "D" = two insulated conductors laid parallel within an outer nonmetallic covering; "M" = two or more insulated conductors twisted spirally within an outer nonmetallic covering. A type letter alone always means a SINGLE insulated conductor.
Optional markings: any Chapter 3 conductor/cable can carry surface markings noting special characteristics — limited smoke, sunlight resistance, and similar properties.
Slide 4 — Quiz + CTA Q: "On a conductor/cable's surface, how often must the AWG size or circular mil area marking repeat?" A) Every 12 in. B) Every 24 in. C) Every 40 in. D) Every 60 in.
✅ Answer: B — 310.8(B)(1): the size marking repeats at intervals not exceeding 24" (610 mm).
CTA: Follow for more daily quick-hit study notes 📚⚡ — Part I complete! Part III (Installation) is next.
⚠️ Educational NoticeQuick Hits are educational explanations based on my understanding of the NEC. Always verify requirements in the current adopted NEC, applicable local amendments, manufacturer instructions, and with the AHJ.
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