Panel schedules are governed by a short article that most electricians have never actually read. It is worth ten minutes, because almost every correction written on a panel directory traces back to one of four sentences.
408.4(A): Circuit Directory or Circuit Identification
The requirement has four distinct parts, and inspectors check them separately.
Every circuit and circuit modification shall be legibly identified as to its clear, evident, and specific purpose or use. Note "circuit modification." If you added a circuit to an existing panel, updating the directory is part of the installation, not a courtesy.
The identification shall include an approved degree of detail that allows each circuit to be distinguished from all others. This is the sentence that kills one word labels. If three circuits say "lights," none of them is distinguished from the others.
Spare positions that contain unused overcurrent devices shall be described accordingly. A breaker sitting in the panel feeding nothing has to say so.
No circuit shall be described in a manner that depends on transient conditions of occupancy. This is the one people find surprising.
The transient occupancy rule, in practice
A circuit description has to stay true after the building changes hands. "Kids room" is wrong the day the kids move out. "Bob's office" is wrong when Bob retires. "Tenant 2" is wrong at the next lease.
Use whatever the structure itself is called: Bedroom 3, Office 102, Suite B, Unit 4. Those survive the people.
| Fails the rule | Passes |
|---|---|
| Grandma's room | Bedroom 1, first floor |
| Dad's shop | Detached garage, receptacles |
| Spare bedroom | Bedroom 4, recept and lighting |
| Tenant's freezer | Basement recept, dedicated, Unit 2 |
Where the directory has to live
For a panelboard, the circuit directory goes on the face of the panel door or inside it. For switchboards and switchgear, identification goes at each switch or circuit breaker rather than in a single directory.
A schedule taped to the wall beside the panel, filed in the building's O&M manual, or stored on somebody's phone does not satisfy this. It has to be on or in the door.
408.4(B): Source of Supply
This is the part that catches contractors moving from residential into commercial work.
All switchboards, switchgear, and panelboards supplied by a feeder, in other than one and two family dwellings, shall be permanently marked to indicate each device or equipment where the power supply originates.
Three things follow from that sentence:
It does not apply to one and two family dwellings. A house panel does not need it.
It applies to feeders, not service conductors. The service equipment itself is not what this is about. Every downstream panel is.
It has to be permanent. A label maker strip is generally accepted. A sharpie line on the dead front generally is not, and neither is a sticker that falls off.
The marking identifies where the power comes from, specifically enough to find it: "Fed from MDP, circuit 14" rather than "Fed from main panel."
What 408.4 does not require
Worth knowing, because people over-build to requirements that are not there.
- It does not require a load calculation on the schedule. Load calcs are required for design under Article 220, but 408.4 does not put them on the door.
- It does not require typed directories. Legible is the standard.
- It does not require listing wire size or breaker type, although both are good practice and the next electrician will thank you.
- It does not require the panel schedule to match a submitted drawing. It requires it to match the panel.
Local amendments can and do add requirements, particularly in commercial jurisdictions. Check your AHJ before assuming the bare NEC text is the whole standard.
Related requirements people conflate with 408.4
| Article | What it covers |
|---|---|
| 110.22(A) | Each disconnecting means marked to indicate its purpose, unless the purpose is evident |
| 210.4(D) | Grouping and identification of multiwire branch circuit conductors |
| 408.3(E) | Phase arrangement on the bus, A B C front to back, top to bottom, left to right |
| 408.4(A) | Circuit directory content and location |
| 408.4(B) | Source of supply marking, non dwelling feeders |
110.22 and 408.4(A) overlap in spirit and get cited interchangeably by inspectors. If the directory is specific and complete, both are satisfied.
For the practical side, including numbering, phase rotation, and multiwire branch circuits, see how to fill out a panel schedule. A blank Excel version with the header fields laid out is on the free panel schedule template page.