Panel circuit directory and labeling
Every circuit in a panel needs a clear, specific and permanent description of what it serves, including spare breakers. In buildings other than one- and two-family homes, feeder-supplied panels must also be marked with where their power comes from.
What the code requires
The code requires a legible, permanent description for every circuit and every circuit modification. On a panelboard, the descriptions go in a circuit directory on the face of the panel door, inside the door, or in an approved location next to the door. On a switchboard, the description goes at each breaker.
Each description must be clear and specific to the circuit's purpose, with enough detail and clarity that circuits are unlikely to be confused. Spare positions holding unused breakers must be described too. Descriptions cannot depend on who happens to occupy a space, such as naming a room after a family member, and any abbreviations or symbols must be explained.
Section 408.4(B) covers switchboards, switchgear and panelboards supplied by a feeder, except in one- and two-family dwellings. Each must be marked with where its power originates and the physical location of that source. The marking must be permanent, suited to the environment and not handwritten.
On the job
- Vague labels, or labels based on who uses a room, are a common inspection correction. The description should say what the circuit actually serves.
- Spare breakers left unlabeled are a correction.
- On commercial and multifamily subpanels, a handwritten source-of-supply label will not pass. It must be a permanent label suited to the location.
Exceptions that matter
- The 408.4(B) source-of-supply marking does not apply to one- and two-family dwellings.
What changed in 2023
The 2023 edition changed the wording from identification to description, reorganized 408.4(A) into a list that adds explaining any abbreviations and symbols used, and added a requirement in 408.4(B) to mark the physical location of the power source.
In California
On new California homes with gas appliances, the 2025 Energy Code also requires reserved breaker spaces that are permanently marked for future 240-volt use (see 408.2).
Related sections
- NEC 110.22
- NEC 408.2: California: reserved breaker spaces in new homes
- NEC 408.6
Where this comes from
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