CSLB C-10 Electrical ContractorSafety and TestingMedium
An electrical contractor is preparing to perform maintenance on a 277V lighting circuit. To ensure safety, a qualified person must conduct an arc flash risk assessment. What is the primary outcome of this assessment according to NFPA 70E?
- ATo determine the required working clearances around the equipment.
- BTo calculate the available fault current at the equipment's terminals.
- CTo determine the arc flash boundary and the appropriate arc-rated PPE.
- DTo identify if lockout/tagout procedures are necessary.
Show answer & explanationAnswer & explanation
Correct answer: C. To determine the arc flash boundary and the appropriate arc-rated PPE.
The primary outcome of an arc flash risk assessment, as per NFPA 70E, is to determine the arc flash boundary and the incident energy at the working distance. This information then dictates the necessary arc-rated personal protective equipment (PPE) required for personnel working within that boundary.
Why the other options are wrong
- A. Working clearances are determined by NEC/CEC, not solely by an arc flash assessment.
- B. Calculating available fault current is a step within the arc flash assessment, but not the primary outcome itself; it's used to determine incident energy.
- D. Lockout/tagout is a separate procedure for de-energizing, not the primary outcome of an arc flash assessment.
Arc Flash Risk Assessment Outcome
The main result of an arc flash risk assessment is the determination of the Arc Flash Boundary and the incident energy level, which guides the selection of appropriate arc-rated personal protective equipment (PPE).
- Identifies arc flash hazards.
- Determines incident energy and arc flash boundary.
- Specifies arc-rated PPE requirements.
- Required by NFPA 70E for safe work practices.
Memory trick: Assess the Flash, Find the Boundary, Get the Gear.