NEC 2023 · Sections 408.4 & 408.36
NEC 408.4 — Circuit Directories & Panelboard Protection
The last item on the finish punch list and one of the easiest red tags to avoid. Here's what the directory has to say, and how the panel itself must be protected.
408.4(A) — What the Directory Must Do
| Requirement | What It Means |
|---|---|
| Legible and specific | Every circuit and circuit modification identified with a clear, evident, specific purpose or use |
| Enough detail to be unique | The description must distinguish each circuit from all others — "lights" three times doesn't pass |
| No transient descriptions | Not based on conditions that change — "Bob's bedroom" fails when Bob moves out; "NW bedroom" doesn't |
| Spares marked | Unused positions and spare devices get identified as spare |
| Located at the panel | Directory on the face or inside the door of a panelboard; at each switch/breaker on a switchboard |
408.4(B) — Where the Power Comes From
Panelboards and switchboards supplied from a source in another building, structure, or a remote part of the same building must be permanently marked with where that supply device is located — so nobody hunts for the feeder breaker during a fault. Field-applied label, durable, at the panel.
408.36 — Protecting the Panelboard Itself
- • Each panelboard is protected by an overcurrent device rated no higher than the panelboard — either a main breaker in the panel or the feeder device upstream.
- • Main-lug-only (MLO) subpanels are fine when the feeder breaker matches: a 100A MLO panel fed from a 100A breaker passes; fed from a 125A breaker it doesn't.
- • Service panelboards follow the service-disconnect rules in Article 230 for their protection arrangement.
- • Related marking: every disconnecting means must be legibly marked to indicate its purpose unless it's obvious (110.22(A)); available fault current marking applies to service equipment (110.24).
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