UC Irvine – High Voltage Electrical Safety Program
Appendix D
Cal/OSHA Clearance and Access Distances
TABLE S-1 - WORKING CLEARANCES
Minimum clear distance
for condition(2) (ft)
Nominal voltage to
ground
0-150
151-600
(a)
(b)
(1)
(1)
3
(1)
3
(c)
3
3 1/2
3
4
(1) Minimum clear distances may be 2 feet 6 inches for
installations built prior to April 16, 1981.
(2) Conditions (a), (b), and (c), are as follows: (a) Exposed live
parts on one side and no live or grounded parts on the other
side of the working space, or exposed live parts on both
sides effectively guarded by suitable wood or other
insulating material. Insulated wire or insulated busbars
operating at not over 300 volts are not considered live parts.
(b) Exposed live parts on one side and grounded parts on
the other side. (c) Exposed live parts on both sides of the
workspace [not guarded as provided in Condition (a)] with
the operator between.
TABLE S-2 - MINIMUM DEPTH OF CLEAR WORKING SPACE IN
FRONT OF ELECTRIC EQUIPMENT
Conditions(2a)
(feet)
Nominal voltage to ground
601 to 2,500
2,501 to 9,000
9,001 to 25,000
25,001 to 75kV(1a)
Above 75kV(1a)
(b)
(a)
3
4
5
6
8
4
5
6
8
10
(c)
5
6
9
10
12
(1a) Minimum depth of clear working space in front of electric
equipment with a nominal voltage to ground above 25,000
volts may be the same as for 25,000 volts under Conditions
(a), (b), and (c) for installations built prior to April 16, 1981.
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UC Irvine – High Voltage Electrical Safety Program
TABLE S-3 - ELEVATION OF UNGUARDED ENERGIZED
PARTS ABOVE WORKING SPACE
Nominal voltage
Minimum elevation
between phases
601 to 7,500
*8 feet 6 inches.
7,501 to 35,000
9 feet.
Over 35kV
9 feet + 0.37 inches kV
above
35kV.
*Note. -- Minimum elevation may be 8 feet 0 inches for
installations built prior to April 16, 1981 if the nominal voltage
between phases is in the range of 601-6600 volts.
Minimum distances for qualified employees from exposed energized live parts (i.e.
the cover of a panel box is removed) are specified by Cal/OSHA regulations and are
shown in the table below.
TABLE S-5 MINIMUM APPROACH DISTANCES FOR
QUALIFIED EMPLOYEES-ALTERNATING CURRENT
Minimum Approach Distance
Nominal Voltage Range
– Phase to Ground
(Phase to Phase) in Kilovolts
Exposure
(kV)
Above 0.6 to 15
2 feet 1 inch
Above 15 to 36
2 feet 4 inches
Above 36 to 46
2 feet 7 inches
Above 46 to 72.5
3 feet 0 inches
Above 72.5 to 121
3 feet 4 inches
Above 121 to 145
3 feet 7 inches
Above 145 to 169
4 feet 0 inches
Above 169 to 242
5 feet 3 inches
Above 242 to 362
8 feet 6 inches
Above 363 to 552
11 feet 3 inches
Above 552 to 765
15 feet 0 inches
Note: Above 242 Kilovolts, the minimum working distance and the minimum approach
distance must be permitted to be reduced, provided that such distances are not less
than the shortest distance between the energized part and a grounded surface.
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