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 4-224 Trimmer approach limit

Utility tree trimmers must respect the limit of approach distances specified in Table 4-5.

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.

Subrule 4-224(2) allows for an air gap as a barrier from a grounded object to eliminate a possible 2nd point of contact and electrical path to ground. This provides the utility tree trimmer with additional protection.

This subrule only applies when tree-trimming work involves the use of insulated tools in an insulated aerial device. It does not apply when moving into position. It is good practice to prevent the insulated portion of the boom or bucket from contacting any grounded objects when moving or repositioning. Travel can be up to but not touching grounded objects when moving the bucket and not trimming.