ENA NENS 04-2006

1 -  ENA NENS 04-2006 NATIONAL GUIDELINES FOR SAFE APPROACH DISTANCES TO ELECTRICAL AND MECHANICAL APPARATUS
4 -  CONTENTS
5 -  1 PREFACE
6 -  2 OBJECTIVES
6 -  3 SCOPE
7 -  4 DEFINITIONS
8 -  5 METHODOLOGY
8 -  5.1 General
10 -  5.2 Authorised Persons, Instructed Persons and Ordinary Persons
10 -  5.3 Power frequency
10 -  5.4 Switching surge
11 -  5.5 Risks excluded
12 -  6 SAFE APPROACH DISTANCES
12 -  6.1 Safe Approach Distance for Ordinary Persons
13 -  6.2 Safe Approach Distances for Instructed or Authorised Persons
14 -  6.3 Safe Approach Distance-Special Limit of Approach for Authorised Persons Only
14 -  6.4 Safe Approach Distances for Mobile Plant Operated by Ordinary Persons
15 -  6.5 Safe Approach Distances for Mobile Plant Operated by Instructed or Authorised Persons
16 -  6.6 Safe Approach Distances for Vehicles Operated by Ordinary Persons
17 -  6.7 Safe Approach Distances for Vehicles Operated by Instructed or Authorised Persons
18 -  6.8 Scaffolding
18 -  7 FACTORS TO CONSIDER IN VARYING SAFE APPROACH DISTANCES
19 -  7.1 Increases to Safe Approach Distances
19 -  7.2 Decreases to Safe Approach Distances-Determination of Special Limits for Authorised Persons Only
20 -  7.2.2 Risk Assessments for Developing Safe Approach Distances-Special Limit for Authorised Persons Only
20 -  7.2.3 Safety Observers
21 -  7.2.4 Mobile plant
21 -  7.3 Variation of calculated electrical withstand distance
21 -  7.3.1 Maximum overvoltage
21 -  7.3.2 Weather conditions
22 -  ANNEX A - BASE ASSUMPTIONS FOR FLASHOVER DERIVATIONS
22 -  A1 GENERAL
22 -  A2 DERIVATION OF POWER FREQUENCY FLASHOVER
22 -  A3 DERIVATION OF SWITCHING SURGE WITHSTAND DISTANCE
23 -  A4 DERIVATION OF D.C. AIR GAP DISTANCES
24 -  ANNEX B - DERIVATION OF SAFE APPROACH DISTANCES FOR INSTRUCTED OR AUTHORISED PERSONS
24 -  B1 PERSONAL APPROACH
25 -  B2 MOBILE PLANT
27 -  ANNEX C - SAMPLE SAFE APPROACH DISTANCE CALCULATIONS
33 -  ANNEX D - TYPES OF PERSONS AND TYPICAL ATTRIBUTES FOR PERSONS TO WORK ON OR NEAR ELECTRICAL APPARATUS
35 -  ANNEX E - REFERENCED DOCUMENTS

These Guidelines are intended to—
(a) Support the Electricity Supply Industry in ensuring the safety of electrical and other
workers and the general public by the development of appropriate Safe Approach
Distances to electrical apparatus for various classes of persons, and mobile plant and
equipment.
(b) Provide the basic technical material necessary for Network Operators to develop
work practice, and related training and awareness programs.
(c) Provide recommendations for appropriate Safe Approach Distances for members of
the general public.
(d) Provide the Electricity Supply Industry with a sound basis for controlling activities,
where possible, of the general public near network assets.

These Guidelines apply to all work on or near electrical apparatus managed by Network Operators, but excluding:
high voltage live work;
work on electrical apparatus which is isolated and earthed and covered by a Network Operator’s Access Authority;
work on electrical installations complying with AS/NZS 3000; and
extra low voltage work.
These Guidelines should be applied in the context that-
(i) Appropriate workplace hazard and risk assessments are carried out as required.
(ii) The Safe Approach Distances used are appropriate for the type of person, training and work to be performed.
(iii) Other Guidelines applicable to particular work processes such as vegetation management are to be used.

First published as ESAA NENS 04-2003.
Redesignated as ENA NENS 04-2006.