Informational Brochure
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.
3
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