Electrical Safety, Codes, and Standards
The Electrical Safety, Codes, and Standards domain tests the administrative and worker-safety side of the trade: NEC scope and listing, NFPA 70E risk assessment, OSHA lockout/tagout and energized-work rules, arc-flash boundaries, and inspection and permit requirements. The exam distinguishes the installation code from the workplace safety standard.
Core rules
- NEC 90.2 defines scope. 110.3 requires listed and labeled equipment; 110.14 covers terminations; 110.16 requires an arc-flash label; 110.24 requires available fault current marking; 110.25 requires a lockable service disconnect.
- NFPA 70E requires an arc-flash risk assessment, identifies the arc-flash boundary and limited and restricted approach boundaries, and specifies PPE. PPE Category 2 is rated 8 cal/cm², Category 3 is 25 cal/cm², and Category 4 is 40 cal/cm².
- OSHA 1910.333 requires de-energizing, lockout/tagout, and verification of absence of voltage. 1910.334 covers test instruments, and 1910.335 covers PPE. Energized work requires justification and increased safety measures.
- Permits and inspections follow the adopted code edition and local amendments. Plans and load calculations may be required before rough-in.
Worked example
A 480 V panel has a calculated incident energy of 8 cal/cm² at the working distance and an arc-flash boundary of 4 ft. The minimum arc-rated clothing is 8 cal/cm², which corresponds to PPE Category 2. Unqualified persons must stay outside the arc-flash boundary unless escorted and protected. The label and the risk assessment, not the voltage alone, determine the PPE; a 480 V panel with a higher incident energy would require a higher category.
Traps
- Treating NFPA 70E as an installation code instead of a workplace safety standard.
- Selecting PPE by voltage only and ignoring the incident-energy calculation.
- Failing to verify absence of voltage after lockout.
- Using a test instrument without the correct CAT rating.
- Assuming a lockout tag alone satisfies the procedure without lockout and verification.