What is in this article?:
- The Secret to Understanding Arc Flash Calculations
- Chapter 1, Safety-Related Work Practices (Art. 100 Definitions)
- Informative Annex C, Limits of Approach
- Informative Annex D, Incident Energy and Arc Flash Boundary Calculation Methods
- Informative Annex H, Guidance on Selection of Protective Clothing and Other Personal Protective Equipment
Applying notes from Annexes C, D, and H of 2012 NFPA 70E
Informative Annex C, Limits of Approach
Annex C introduces the following logical concept:
“As the distance between a person and the exposed energized conductors or circuit parts decreases, the potential for electrical accident increases.”
It also breaks down the discussion of safe approach distance for both unqualified and qualified persons.
The Annex also illustrates the limits of approach, the basic concept of which is illustrated in Figure 1:
Table 130.4(C)(a) of NFPA 70E introduces “Approach Boundaries to Energized Electrical Conductors or Circuit Parts for Shock Protection, Alternating-Current Voltage Systems.” The prohibited approach boundary, restricted approach boundary, and limited approach boundary are all dependent on system voltage.