OHS Code Explanation Guide

Published Date: July 01, 2009
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Part 40 Utility Workers – Electrical

Explanation of Rules Referenced from the ECUC, Second Edition

Rule 4-134 Tree work distances

In paragraph (a), utility tree trimmers performing tree work near energized power lines follow the limit of approach distances listed in Table 4-5. The decreased approach distances shown in columns 5(2) and 6(3) of Table 4-5 reflect the fact that in some cases insulated tools are being used, while in others the work is done out of an insulated aerial device that is electrically rated and insulated.

Table 4-5 Limit of Approach Distances in Millimetres for Utility Tree Trimmers

Voltage Levels

Utility tree trimmers

Nominal
voltage to
ground
 
 
kV

Nominal
voltage
phase to
phase
 
kV

Maximum
operating
voltage phase
to phase
 
kV

Limit of
approach for
utility tree
trimmers and
conducting
objects to
exposed
energized
parts
 
mm

Limit of
approach for
rated
insulating
tools to
exposed
energized
parts
 
 
mm

Limit of
approach for
rated
insulating
booms
 
 
 
 
 
mm

Column 1

Column 2

Column 3

Column 4(1)

Column 5(2)

Column 6(3)

0.6 (DC only)

 

 

1050

40

500

2.4

4.16

4.58

1050

40

500

8

13.8

15.18

1100

120

550

14.4

25

27.5

1200

210

650

19.9

34.5

37.95

1300

290

750

 

69, 72

79.2

1600

610

1050

 

138, 144

158.4

1900

920

1350

 

230, 260

285

2400

1410

1850

 

500

550

3700

2710

3150

Note:
(1) Limit of approach distances in Column 4 have been calculated using IEEE minimum tool distances plus 1000 mm safety factor, rounded to the nearest 50 mm.
(2) Limit of approach distances in Column 5 have been calculated using IEEE minimum tool distances, rounded to the nearest 10 mm.
(3) This column does not apply to utility or qualified utility employees doing tree work near energized electrical equipment or lines.

Paragraph (b) requires utility tree workers and utility workers to follow the “regular” approach distances of Table 2-1 that apply to persons and equipment. Utility tree workers are not qualified to perform aerial trimming so different rules apply to them as compared to utility tree trimmers.

Table 2-1 Limits of Approach Distances from Overhead Power Lines for Persons and Equipment (See Rules 2-012 & 4-134)

Operating voltage of overhead power line
between phase conductors

Safe limit of approach distance for persons
and equipment

0 - 750 V insulated or polyethylene
covered conductors (1)

0.3 m

0 - 750 V bare, uninsulated

1.0 m

Above 750 V insulated conductors (1)(2)

1.0 m

.75 kV - 40 kV

3.0 m

69 kV, 72 kV

3.5 m

138 kV, 144 kV

4.0 m

230 kV, 260 kV

5.0 m

500 kV

7.0 m

Note:
(1) Conductors must be insulated or covered throughout their entire length to comply with these groups.
(2) Conductors must be manufactured to rated and tested insulation levels.