Up until the latest edition of the National Electrical Code (NEC) in the 2017, the requirements at 408.4 were as follows:

1. Every circuit must be legibly identified to its specific purpose or use.
2. The identification must be sufficient to distinguish it from all others. In other words, a cluster of 120-volt circuits all called “general purpose,” or “receptacles,” or something like that is not acceptable.
3. The circuit directory must be located on the face of panel or inside of the panel door
4. Unused (spare) breakers should also be identified. 

The 2017 NEC added these additional  requirements, but they do not apply to residential construction (one- or two-family dwellings):

1. Marking must be permanent, permanently affixed, and durable enough to withstand the environment where located.
2. Not handwritten.

    Anyone who has ever struggled to read a loose, yellowed and tattered paper circuit directory, written in a faded, hard-to-read scrawl, with things scratched-out and overwritten, hanging by a single piece of tape on the inside of a panel door, will appreciate the reason for this code citation. 

    Also, see our blog posts Can an unused (spare) circuit breaker remain in an electrical panel or does it have to be removed? and What is the maximum number of circuit breakers allowed in an electric panel? and What is the maximum allowed height of a circuit breaker (OCPD) above the floor?

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Here’s links to a collection of our other blog posts about ELECTRIC PANELS:

• What causes copper wires to turn green or black in an electric panel?  

• When should a corroded or damaged electric panel cabinet or disconnect box be replaced? 

• What is a tandem circuit breaker? 

• When did arc fault circuit interrupter (AFCI) breakers first become required?

• Can an electric panel be located in a closet? 

• Can an electric panel be located in a bathroom? 

• Can you add circuit breakers by different manufacturers to an electric panel if they fit?

• My circuit breaker won't reset. What's wrong?  

• What is a split bus electric panel?

• How do I identify a combination AFCI (CAFCI) circuit breaker? 

• What does a circuit breaker with a yellow or white test button indicate? 

• What is the maximum gap allowed between the front of a recessed electric panel box and the wall surface surrounding it? 

• What are the requirements for NM-cables entering an electric panel box?

• Why is a fuse box/panel an insurance problem for homebuyers? 

• Why is bundled wiring in an electric panel a defect?

• What is the difference between GFCI and AFCI circuit breakers? 

• Why are old electrical components not always "grandfathered" as acceptable by home inspectors?

• What happens when you press the "TEST" button on a circuit breaker in an electric panel?

• What is a Dual Function Circuit Interrupter (DFCI)? 

• What is the difference between a Combination Arc Fault Circuit Interrupter (CAFCI) and an Arc Fault Circuit Interrupter (AFCI) circuit breaker?  

• What is the difference between "grounded" and "grounding" electrical conductors? 

• What does it mean when a wire is "overstripped" at a circuit breaker?

• Why is an old fuse panel dangerous?  

• Who is the manufacturer of those "bad" electric panels?

• Why is the circuit breaker stuck in the middle? 

• What is a double tap at a circuit breaker?

• What is the right electric wire size for a circuit breaker in an electric panel?

• What is the life expectancy of a circuit breaker? 

• What is the maximum height you can mount an electric panel above the floor? 

• What is a "missing knockout" or "open knockout" in an electric panel box? Why is it a problem?

    Visit our ELECTRIC PANELS page for other related blog posts on this subject, or go to the INDEX for a complete listing of all our articles.