Electrical Safety and NFPA 70E Practices
The 70E framework
NFPA 70E is a work-practice standard, not an installation code. Article 110 requires an electrical safety program, training, and a risk assessment procedure. Article 120 defines establishing an electrically safe work condition: identify all sources, disconnect, verify, lock and tag, release stored energy, verify absence of voltage with a tested tester, and ground if needed. Article 130 covers job planning, approach boundaries, arc flash risk assessment (130.5), and PPE (130.7).
Boundaries and PPE
- Shock protection uses limited, restricted, and arc flash boundaries from Table 130.4(E)(a). At 480 V the restricted approach boundary is typically 1 ft for fixed circuit parts.
- The arc flash boundary comes from an incident energy calculation or Table 130.7(C)(15).
- Where incident energy is 1.2 cal/cm² or greater, arc-rated clothing is required, and its arc rating must meet or exceed the incident energy.
- Rubber insulating gloves require leather protectors and an air test before use.
Worked example
A task on a 480 V panel has a calculated incident energy of 4 cal/cm² at an 18 in. working distance. Reasoning: select arc-rated PPE with an arc rating of at least 4 cal/cm², respect the restricted approach boundary unless the equipment is placed in an electrically safe work condition and verified, and wear shock-protective gloves rated for 480 V. Voltage alone does not set PPE; the incident energy does.
Traps
- Treating a voltage glove as arc flash protection.
- Verifying absence of voltage with an untested meter.
- Skipping lockout because another worker is present.
- Using a PPE category table when a site-specific arc flash study exists.