Appendix N: Working Definitions for Approach Boundaries


SHOCK PROTECTION BOUNDARIES

NFPA 70E, Table 130.2

Limited Approach Boundary — Defines the closest approach to an exposed electrical hazard, (conductor, component, etc.), for non-qualified personnel, unless escorted by a qualified worker. Determines the minimum safe distance for the placement of barricades for shock protection. If the qualified electrical workers are unable or unwilling to provide escort for unqualified workers, the unqualified worker may not enter the limited approach boundary.

Restricted Approach Boundary — Qualified and Authorized electrical workers only. All required PPE appropriate to the shock hazard must be worn. The worker is now working near the exposed hazard. The worker must have an approved plan for the work they are to perform. They may cross the restricted boundary only to the extent that is necessary to perform their work.

Prohibited Approach Boundary — All of the requirements for limited and restricted boundaries apply. Any work inside the prohibited boundary is considered the same as being in contact with the exposed uninsulated conductor. No electrically uninsulated part of the body may cross the prohibited approach boundary.

Table 130.2(C) Approach Boundaries to Live Parts for Shock Protection. (All dimensions are distance from live part to employee.)

(1)
(2)
(3)
(4)
(5)
Limited Approach Boundary1
Nominal System Voltage Range, Phase to Phase2
Exposed Movable Conductor3
Exposed Fixed Circuit Part
Restricted Approach Boundary1; Includes Inadvertent Movement Adder
Prohibited Approach Boundary1
Less than 50
Not specified
Not specified
Not specified
Not specified
50 to 300
3.05 m (10 ft 0 in.)
1.07 m (3 ft 6 in.)
Avoid contact
Avoid contact
301 to 750
3.05 m (10 ft 0 in.)
1.07 m (3 ft 6 in.)
304.8 mm (1 ft 0 in.)
25.4 mm (0 ft 1 in.)
751 to 15 kV
3.05 m (10 ft 0 in.)
1.53 m (5 ft 0 in.)
660.4 mm (2 ft 2 in.)
177.8 mm (0 ft 7 in.)
15.1 kV to 36 kV
3.05 m (10 ft 0 in.)
1.83 m (6 ft 0 in.)
787.4 mm (2 ft 7 in.)
254 mm (0 ft 10 in.)
36.1 kV to 46 kV
3.05 m (10 ft 0 in. )
2.44 m (8 ft 0 in.)
838.2 mm (2 ft 9 in.)
431.8 mm (1 ft 5 in.)
46.1 kV to 72.5 kV
3.05 m (10 ft 0 in.)
2.44 m (8 ft 0 in.)
1.0 m (3 ft 3 in.)
660 mm (2 ft 2 in.)
72.6 kV to 121 kV
3.25 m (10 ft 8 in.)
2.44 m (8 ft 0 in.)
1.29 m (3 ft 4 in.)
838 mm (2 ft 9 in.)
138 kV to 145 kV
3.36 m (11 ft 0 in.)
3.05 m (10 ft 0 in.)
1.15 m (3 ft 10 in.)
1.02 m (3 ft 4 in.)
161 kV to 169 kV
3.56 m (11 ft 8 in.)
3.56 m (11 ft 8 in.)
1.29 m (4 ft 3 in.)
1.14 m (3 ft 9 in.)
230 kV to 242 kV
3.97 m (13 ft 0 in.)
3.97 m (13 ft 0 in.)
1.71 m (5 ft 8 in.)
1.57 m (5 ft 2 in.)
345 kV to 362 kV
4.68 m (15 ft 4 in.)
4.68 m (15 ft 4 in.)
2.77 m (9 ft 2 in.)
2.79 m (8 ft 8 in.)
500 kV to 550 kV
5.8 m (19 ft 0 in.)
5.8 m (19 ft 0 in.)
3.61 m (11 ft 10 in.)
3.54 m (11 ft 4 in.)
765 kV to 800 kV
7.24 m (23 ft 9 in.)
7.24 m (23 ft 9 in.)
4.84 m (15 ft 11 in.)
4.7 m (15 ft 5 in.)

ARC FLASH PROTECTION BOUNDARY

NFPA 70E, Article 130.3(A)

Flash Protection Boundary — Set at the distance from the arc source for a second degree burn.

May be placed outside the limited approach boundary. If so, then the flash protection boundary is the outer most defining boundary and will determine the placement of barricades. The requirements for working inside this boundary are identical to the requirements for working inside the restricted approach boundary, plus arc flash protection appropriate to the arc-flash hazard.

ARC FLASH PROTECTION BOUNDARY.

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