Outdoor Air Switches

Selection on Basis of Insulation Level

Table 3 - Ground Clearance

Clearance Between Overhead Conductors & Ground for Personnel Safety

Clearance Between Overhead Conductors & Roadways Inside Enclosure

Clearance to Ground for Rigid Parts

Ratings, kV

Recommended Inches

Minimum Inches

Recommended Feet

Minimum Feet

Recommended Feet

Minimum Feet

Nominal

BIL

Maximum Design

7 1/2

95

8.3

7.2

6 7

10 10 10 11 11 12 13 14 14 15 16 16 18

8 9

21 21 21 22 22 23 24 25 25 26 28 28 30

20 20 20 22 22 23 24 25 25 26 28 28 30

15.5

14.4

110 150 200 250 350 550 650 750 900

10 12 15 18 29 47

27 38

23

10 13 17 25 42 50 58 71 83 84

10 10 10 11 12 13 14 15 16 16 18

34.5

48.3 72.5 123 145 170 245 245 362 362

46 69

115 138 161 230 230 345 345

52 1/2 61 1/2 90 1/2 90 1/2 76

1050 1050 1300

106

104

Above 362 kV maximum design, electrical clearances are dictated by expected maximum switching surge voltage levels.

Table 4 - Phase Spacing

Recommended Φ to Φ Inches

Ratings, kV

Vertical Break Disc. Switch with GRD Switch

Double Side Break Disc. Switch & Bus Supports

Vertical Break Disc. Switch

Live Parts Minimum Metal-to- Metal

Single Side Break Disc. Switch

Center Side Break Disc. Switch

2500 & 3000 Amp 30° Rise

Horn Gap Switch

600 thru 3000 Amp

600 thru 2000 Amp 3" B.C.

Maximum Design

2500 & 3000 Amp 5" B.C.

Nominal

BIL

4000 Amp

8.3

7.2

95

7

18 24 30 36 48 60 84 96

36 36 39 42 48 60 84 96

36 38 42 46 50 60 84 96

40 40 44 48 52 60 84 96

18 24 30 36 48 60 84 96

30 30 36 48 60 72

30 30 36 48 60 72

36 36 48 60 72 84

d d

c c c c c c

c c c c c c

15.5

14.4

110 150 200 250 350 550 650 750 900

12 15 18 21 31 53 63 72 89

27 38

23

34.5

48.3 72.5 123 145 170 245 245 362 362

46 69

115 138 161 230 230 345 345

108 132 156 192 216 216 240

108 132 156 192 216 216 240

120 144 168 192 216 216 240

108 132 156 156 174

108 132 156 156 174

108 132 156 156 174

108 132 156 156 174

108 132 156 156 174

1050 1050 1300

105 105 119

Above 362 kV maximum design, electrical clearances are dictated by expected maximum switching surge voltage levels. Notes: c Minimum Dimension d Use Disc. Switch dimension if greater.

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