When working with electrical equipment, it's crucial to understand the different boundaries that define safe zones for workers. The National Fire Protection Association (NFPA) 70E (2018) outlines a systematic approach to reducing hazards and risk through its Hierarchy of Controls. One essential aspect of this hierarchy is the establishment of three distinct boundaries: limited approach boundary, restricted approach boundary, and arc flash boundary.

Understanding These Boundaries

The limited approach boundary refers to the 'stay back' distance for non-qualified workers, where they may be exposed to a shock hazard. On the other hand, the restricted approach boundary is an area closer to live equipment, where only qualified workers with proper training are allowed to enter. This zone requires specialized protection and the escort of a qualified person.

The arc flash boundary, specifically, refers to the distance at which a worker will receive second-degree burns in the event of an arc flash incident without appropriate arc-rated personal protective equipment (PPE). Depending on the potential arc flash hazard, this boundary is calculated separately based upon specific system information or determined through NFPA 70E Tables 130.4(C)(a) for AC systems and 130.4(C)(b) for DC systems.

The 2-Man Rule in Arc Flash Boundary

When working within the arc flash boundary, it's essential to have a qualified worker accompany another worker who may not be fully trained or equipped. This is commonly referred to as the '2-man rule.' The idea behind this rule is that having two workers together can help prevent accidents and ensure that one worker can provide assistance if needed.

Key Takeaways

1. NFPA 70E (2018) emphasizes the importance of understanding the Hierarchy of Controls in reducing hazards and risk.

2. The limited approach boundary refers to the 'stay back' distance for non-qualified workers, while the restricted approach boundary requires qualified workers with proper training.

3. The arc flash boundary is calculated separately based upon specific system information or determined through NFPA 70E Tables 130.4(C)(a) and (b).

4. The 2-man rule is essential when working within the arc flash boundary to ensure worker safety.

Establishing clear boundaries for workers in electrical environments is vital for reducing hazards and risk. By understanding the limited approach, restricted approach, and arc flash boundaries, as well as the importance of the 2-man rule, workers can take necessary steps to protect themselves and others from electrical-related incidents. As part of a comprehensive training program, these boundaries should be strictly adhered to in order to minimize risk through avoidance or the use of PPE.

2 man rule in arc flash boundary