M421-16
Use of electricity in mines
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M421-16
December 2016
Title: Use of electricity in mines
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Use of electricity in mines
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Use of electricity in mines
M421-16
Contents
Technical Committee on Use of Electricity in Mines
Preface
6
10
1 Scope 12
1.1
Purpose 12
1.2
Application 12
1.3
Application to non-mining structures
1.4
Structure of this Standard 12
1.5
Terminology 12
2 Reference publications
3 Definitions
12
13
15
4 General requirements 18
4.1
Application 18
4.2
Miscellaneous 19
4.2.1
Mine plans 19
4.2.2
Supervision and work 19
4.2.3
Temporary installations 19
4.2.4
Out-of-service wiring 20
4.2.5
Work on energized equipment 20
4.2.6
Fire-extinguishing device 20
4.2.7
Notices to workers 21
4.3
Wiring methods 21
4.3.1
Cables 21
4.3.2
Portable and mine power feeder cables 21
4.3.3
Portable power cables (usage) 22
4.3.4
Shielding for cables supplying mobile electrical equipment
4.3.5
Wiring of magazines for storing explosives and detonators
4.3.6
Overhead supply lines 24
4.4
Installation of equipment 25
4.4.1
Movable and mobile equipment 25
4.4.2
Quick-connect cable couplers 26
4.4.3
Conveyor systems 26
4.4.4
Overhead travelling cranes 27
4.4.5
Portable and movable generators 27
4.5
Protection and control 29
4.5.1
Isolating switches 29
4.5.2
Closing by gravity 29
4.5.3
Interlocking of isolating devices 29
4.5.4
Protection and control of transformers 29
4.5.5
Testing and calibration of protection devices 29
4.5.6
Ground-fault protection 29
4.5.7
Ground-conductor monitoring 30
December 2016
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23
23
1
Use of electricity in mines
M421-16
4.5.8
4.5.9
4.6
4.6.1
4.6.2
4.6.3
4.6.4
4.7
4.7.1
4.7.2
4.7.3
4.7.4
4.7.5
4.7.6
4.7.7
4.7.8
4.7.9
4.8
4.8.1
4.8.2
4.8.3
4.8.4
4.9
4.10
4.11
4.11.1
4.11.2
Hand-held equipment 30
Automatic reclosing of power circuits 30
Grounding 30
Circuit-opening devices in grounding conductors 30
Neutral-grounding devices 30
Ground-fault indication 30
Grounding in permafrost conditions 31
Electric blasting 31
General 31
Supply characteristics 31
Conductors 31
Stray current precautions 32
Control 32
Blasting switch 32
Multiple blasting 32
Maintenance 32
Programmable logic control (PLC) 33
Lightning protection 33
General 33
Overhead lines 33
Guard wires or structures 34
Headframes 34
Radio-controlled equipment 34
Safety-related maintenance 34
Outdoor electrical equipment — Fence enclosures 34
General 34
Maintenance 34
5 Surface mines and quarries 34
5.1
Application 34
5.2
Electrical equipment rooms 35
5.2.1
General 35
5.2.2
Illumination 35
5.3
Movable switch houses and substations 35
5.3.1
Primary connections to a movable switch house or substation from overhead supply lines
5.3.2
Movable switch houses 35
5.3.3
Movable substations 36
5.4
Mobile electrical equipment 36
5.4.1
Scope 36
5.4.2
Miscellaneous 37
5.4.3
Wiring methods 37
5.4.4
Installation of equipment 39
5.4.5
Grounding 39
5.4.6
Access control to high-voltage equipment 39
5.4.7
Protection and control devices 40
6 Underground mines 40
6.1
Application 40
6.2
Electrical equipment rooms
December 2016
35
40
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2
Use of electricity in mines
M421-16
6.3
6.3.1
6.3.2
6.3.3
6.3.4
6.4
6.4.1
6.4.2
6.4.3
6.4.4
6.4.5
6.4.6
6.5
6.5.1
6.5.2
6.5.3
6.6
6.6.1
6.6.2
6.7
6.7.1
6.7.2
6.7.3
6.8
6.8.1
6.8.2
6.8.3
6.9
6.9.1
6.9.2
6.9.3
6.10
6.10.1
6.10.2
6.10.3
6.10.4
6.10.5
6.10.6
6.10.7
6.10.8
6.10.9
6.10.10
6.10.11
6.10.12
6.10.13
6.10.14
6.10.15
6.10.16
6.11
Wiring methods 40
Conductors 41
Flame test rating 43
Splices 44
Junction boxes 44
Installation of transformers and capacitors 44
Surface transformers — Flash point less than 275 °C 44
Underground transformers — General 44
Underground transformers — Flash point less than 275 °C 45
Underground transformers — Flash point greater than 275 °C 45
Underground transformers — Gas filled or dry type 45
Capacitors 46
Switchboards and switchgear 46
General 46
Flash point less than 275 °C 47
SF6 Gas filled switchgear 47
Electromagnets 47
Flash point less than 275 °C 47
Flash point greater than 275 °C 47
Installation of storage batteries 47
Location 47
Installation 47
Disposal 48
Grounding 48
Grounding circuit 48
Inspection 48
Ground potential rise (GPR) 48
Communication systems 48
Voice communication 48
Cage call system 49
Shaft signal system 49
Mine hoists 49
General 49
Proving tests 49
Protective circuits 50
Backout device 51
Metering 51
Approach warning signal 51
Depth indicator 51
Personnel safety device 52
Emergency stop alarm 52
High-water-level probe 52
Operation of level-installed controls 52
Operation of cage-installed controls 53
Friction hoists 53
Hoist maintenance operations 53
Shaft sinking 53
Hoist maintenance and records 53
Transportation 54
December 2016
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3
Use of electricity in mines
M421-16
6.11.1
6.11.2
6.11.3
6.11.4
6.11.5
6.11.6
6.12
General 54
Warning equipment 54
Control 54
Trolley wires 55
Haulage rails 56
Conductors in passages 56
Non-rail bound mobile electrical equipment
56
7 Underground coal mines 57
7.1
Application 57
7.2
General 57
7.2.1
Electrical equipment 57
7.2.2
Use of electricity 58
7.2.3
Auxiliary ventilation 58
7.3
Work on energized equipment — Repairs and alterations 58
7.4
Voltage at coal face 58
7.5
Main fans 58
7.6
Distribution system integrity 58
7.7
Wiring methods for non-intrinsically-safe wiring 59
7.7.1
Cables 59
7.7.2
Portable power cables 59
7.7.3
Connectors or couplers 60
7.7.4
Feeder and branch circuits 60
7.7.5
AC supply to mobile electrical equipment 60
7.8
Installation of equipment 61
7.8.1
General 61
7.8.2
Transformers 61
7.8.3
Switchboards and switchgear 62
7.8.4
Storage battery rooms or other enclosures and battery-charging areas
7.8.5
Conveyor systems 63
7.9
Protection and control 63
7.9.1
General 63
7.9.2
Protection 64
7.9.3
Control 64
7.10
Grounding 64
7.10.1 General 64
7.10.2 DC systems 64
7.10.3 Grounding of ac systems 64
7.11
Intrinsically safe systems — Signal systems 65
7.12
Mine lighting 65
7.12.1 General 65
7.12.2 Operating voltage 65
7.12.3 Protection 65
7.12.4 High-intensity-discharge lighting 66
7.12.5 HID lamps containing elements of sodium 66
7.13
Shotfiring 66
7.13.1 General 66
7.13.2 Shotfiring apparatus 66
7.13.3 Shotfiring cable 67
December 2016
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62
4
Use of electricity in mines
M421-16
7.13.4
Installation and use
67
Annex A (informative) — Ground potential rise and ground-fault voltage 72
Annex B (informative) — Overhead supply line clearances 74
Annex C (informative) — Mine hoists 76
Annex D (informative) — Maintenance 81
Annex E (informative) — Electrical installations in ammonium nitrate fuel oil (ANFO) areas 82
Annex F (informative) — Options for equipment control power 88
Annex G (informative) — Equipment protection levels and methods of explosion protection for
underground coal mines 92
Annex H (informative) — Underground coal mine ac system grounding considerations 97
Annex I (informative) — Flame test ratings 98
December 2016
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5
Use of electricity in mines
M421-16
Technical Committee on Use of Electricity
in Mines
R.C. Banting
Workplace Safety North,
North Bay, Ontario
Category: General Interest
Chair
C. Leduc
Mining Electrical Safety Forum (Ontario),
Sudbury, Ontario
Category: General Interest
Vice-Chair
K. Ansari
Startco Engineering ULC,
Saskatoon, Saskatchewan
Associate
B.M. Baldwin
Baldwin Services Inc.,
Saskatoon, Saskatchewan
Category: Producer Interest
M. Beauregard
BBA Inc.,
Mont-St-Hilaire, Québec
Associate
E. Boulay
Unifor,
Dowling, Ontario
Associate
T. Brotherston
Cementation Canada Inc.,
North Bay, Ontario
Associate
K. Clement
United Wire & Cable Incorporated,
Richmond Hill, Ontario
Associate
A.G. Cooke
Regina, Saskatchewan
Category: General Interest
R.P. de Lhorbe
Schneider Electric Canada, Inc.,
Richmond, British Columbia
Category: Producer Interest
R. Desaulniers
Goldcorp Canada Musselwhite Mine,
Thunder Bay, Ontario
J. Donnelly
SaskPower Electrical Inspections,
Saskatoon, Saskatchewan
Category: Regulatory Authority
December 2016
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Associate
6
Use of electricity in mines
M421-16
G. Drewes
International Brotherhood of Electrical Workers
Local 402,
Thunder Bay, Ontario
Category: User Labour
M. Duncan
Nexans AmerCable,
Stettler, Alberta
M.A. Fuller
Nexans AmerCable Inc.,
Beaver, Pennsylvania, USA
Category: Producer Interest
F. Gauthier
CNESST,
Québec, Québec
Category: Regulatory Authority
R. Grant
Nova Scotia Department of Labour & Advanced
Education,
Sydney, Nova Scotia
Category: Regulatory Authority
R. Hakam
Manufacture Adria Inc.,
Kelowna, British Columbia
Associate
K. Hryniw
Teck Coal Ltd. Coal Mountain Operations,
Sparwood, British Columbia
Associate
L. Kaskiw
Government of Saskatchewan Ministry of Labour
Relations & Workplace Safety,
Saskatoon, Saskatchewan
Associate
R.F. King
RF King & Associates Inc.,
Brentwood Bay, British Columbia
Category: General Interest
M.R. Levitre
Southwire Company,
Carrollton, Georgia, USA
G. Lobay
CSA Consumer Network,
Ottawa, Ontario
Category: General Interest
K.J. Lueschow
Caterpillar Inc.,
Peoria, Illinois, USA
December 2016
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Associate
Associate
Associate
7
Use of electricity in mines
M421-16
G. Mallette
Syncrude Canada Ltd.,
Calgary, Alberta
Category: User Management
N. Moubed
Anixter Canada Inc.,
Mississauga, Ontario
Associate
S. Nair
WorkSafe BC,
Richmond, British Columbia
Associate
E. Padley
British Columbia Ministry of Energy,
Kamloops, British Columbia
Category: Regulatory Authority
R. Pawluk
United Wire & Cable Incorporated,
Richmond Hill, Ontario
Category: Producer Interest
A. Peart
Canadian Labour Congress,
Ottawa, Ontario
K. Peters
Alamos Gold,
Matachewan, Ontario
Category: User Labour
D. Richardson
Stantec Consulting,
North Bay, Ontario
Associate
J.W. Rogers
JW Rogers Consulting,
Big Bras D’or, Nova Scotia
Associate
T. Samson
BESTECH,
Sudbury, Ontario
Associate
J. Solberg
Shermco Industries Canada Inc.,
Regina, Saskatchewan
Category: User Management
C.J. Spackman
Imperial Oil,
Calgary, Alberta
Associate
C.T. Spackman
Spackman and Associates,
High River, Alberta
Associate
December 2016
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Associate
8
Use of electricity in mines
M421-16
A.B. Sprague
Muskego, Wisconsin, USA
Category: Producer Interest
T. Tremblay
Electrical Safety Authority,
Sudbury, Ontario
Associate
A. van Niekerk
Grande Cache Coal Corp.,
Grande Cache, Alberta
Associate
J. Wedzicha
Ontario Ministry of Labour,
Sudbury, Ontario
Category: Regulatory Authority
B. Wentzell
Vale,
Thompson, Manitoba
Category: User Management
N. Wight
Potash Corporation of Saskatchewan,
Saskatoon, Saskatchewan
Category: User Management
O. Simonetta
CSA Group,
Toronto, Ontario
December 2016
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Project Manager
9
Use of electricity in mines
M421-16
Preface
This is the fifth edition of CSA M421, Use of electricity in mines, one of a series of Standards on mine
safety. It supersedes the previous editions, published in 2011, 2000, 1993, and 1985.
The following significant revisions have been made to this edition:
a) Clauses 4.3.1.3 and 4.3.1.4 on vertical cable installations have been revised to clarify the criteria for
vertical cable installations.
b) New Clause 4.3.3.3 recognizes the use of portable power cable marked TC in cable tray, with
references to the Canadian Electrical Code, Part I.
c) New Clause 4.4.2.1 requires that cable couplers operating at voltages exceeding 750 V meet the
requirements of CSA C22.2 No. 298.
d) New Clause 4.5.9 requires the auto-reclosing functions of circuit breakers be turned off by default
and are only permitted to be activated after a safety study is performed.
e) Clause 5.3.1 c) has been revised to recognize connections to a movable switch house or substation
by way of an interlocked plug.
f) Existing Clauses 5.4.3.2.2 and 6.3.2 on flame test rating have been revised to reflect the current
CSA C22.2 specifications.
g) New Clause 5.4.3.2.3 on external portable power cables excludes the requirement of a flame test
rating for cables external to the mobile equipment.
h) New Clause 6.2 on electrical equipment rooms defines general requirements for electrical
equipment rooms located underground in mines. This addition resulted in incremental
renumbering for the remainder of Clause 6.
i) Clause 6.3.1 on conductors clarifies requirements for support, design, and cable pulling.
j) Clauses 6.4.2 and 6.5, dealing with underground transformers and switchgear, introduces the
CAN/BNQ 2910-510 requirements for the installation locations relative to explosives.
k) Clause 6.4.5 on underground transformers introduces new requirements specific to nitrogen and
SF6 gas filled transformers.
l) New Clause 6.8.3 on ground potential rise specifies a maximum value for GPR and transfer of
potential at movable or mobile equipment.
m) Clause 6.10.3.4 on mine hoist protective circuit introduces a “control reliable” requirement, as
detailed in CSA Z432, for the manually operable switch (E-stop).
n) Clause 6.11.5.2 on haulage rails has a new requirement for annual inspection of rail bonds.
o) Clause 7.2.1 on electrical equipment has been revised to align requirements with the Canadian
Electrical Code, Part I. As a result of this change, a number of clauses were deleted causing the
renumbering of subsequent clauses.
p) A new informative Annex F on options for equipment control power has been added to clarify
application aspects of different methods of control power as they relate to the power system,
particularly for fail-safe circuits (e.g., UPS sources, undervoltage vs. shunt tripping methods).
q) A new informative Annex G on equipment protection levels and methods of explosion protection
for underground coal mines has been added to provide guidance when using Group I electrical
equipment that is approved for use in underground coal mines under the IEC 60079 series of
standards and its associated system of equipment protection levels (EPL).
r) A new informative Annex H on underground coal mine ac system grounding considerations
provides recommendations for system grounding as they relate to Clause 7.10.3.
s) A new informative Annex I on flame test ratings provides an overview of various flame tests and
their relative severity.
December 2016
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10
Use of electricity in mines
M421-16
This Standard, used in conjunction with the Canadian Electrical Code, Part I, establishes minimum safety
standards for the installation and maintenance of electrical equipment in mines or other mining
applications requiring special consideration beyond the requirements of the Canadian Electrical Code,
Part I.
This Standard is not intended as a design specification nor as an instruction manual for untrained
persons.
In the preparation of this Standard, consideration has been given to the prevention of fire hazards and
injury to persons and property, and to proper maintenance and operation. Due regard has been given to
recognized codes and standards now in force.
This Standard was prepared by the Technical Committee on Use of Electricity in Mines, under the
jurisdiction of the Strategic Steering Committee on Occupational Health and Safety, and has been
formally approved by the Technical Committee.
Notes:
1) Use of the singular does not exclude the plural (and vice versa) when the sense allows.
2) Although the intended primary application of this Standard is stated in its Scope, it is important to note that it
remains the responsibility of the users of the Standard to judge its suitability for their particular purpose.
3) This Standard was developed by consensus, which is defined by CSA Policy governing standardization — Code
of good practice for standardization as “substantial agreement. Consensus implies much more than a simple
majority, but not necessarily unanimity”. It is consistent with this definition that a member may be included in
the Technical Committee list and yet not be in full agreement with all clauses of this publication.
4) To submit a request for interpretation of this Standard, please send the following information to
inquiries@csa.ca and include “Request for interpretation” in the subject line:
a) define the problem, making reference to the specific clause, and, where appropriate, include an
illustrative sketch;
b) provide an explanation of circumstances surrounding the actual field condition; and
c) where possible, phrase the request in such a way that a specific “yes” or “no” answer will address the
issue.
Committee interpretations are processed in accordance with the CSA Directives and guidelines governing
standardization and are available on the Current Standards Activities page at standardsactivities.csa.ca.
5) This Standard is subject to review within five years from the date of publication. Suggestions for its
improvement will be referred to the appropriate committee. To submit a proposal for change, please send the
following information to inquiries@csagroup.org and include “Proposal for change” in the subject line
a) Standard designation (number);
b) relevant clause, table, and/or figure number;
c) wording of the proposed change; and
d) rationale for the change.
December 2016
© 2016 CSA Group
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11
M421-16 11
Use of electricity in mines
1 Scope
1.1 Purpose
This Standard establishes minimum requirements for electrical work and electrical equipment
operating, or intended to operate, in mines at a mine.
Note: Users should be aware that federal, provincial, and territorial legislation can impose additional
requirements.
1.2 Application
This Standard is intended supplementary to be used with , or amendatory of, the requirements of
the Canadian Electrical Code, Part I, as adopted by the regulatory authority having jurisdiction or local
regulatory amendment thereto, unless such requirements are modified by this Standard.
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Note: Adherence to the Canadian Electrical Code, Part I, normally addresses the minimum electrical safety
requirements for mining-related fixed buildings, structures, and premises located on the surface, as these are
no different from other industrial facilities. Such facilities could include processing plants, camps, offices, and
drys. However, specific applications can exist within or on such buildings, structures, or premises that
warrant the application of this Standard, e.g., the following equipment operating at voltages exceeding 150 V
to ground:
a)
mobile equipment fed by portable power cables;
b)
movable equipment fed by portable power cables where the ground-fault voltage and ground potential
rise (GPR) relative to the surrounding earth or structures is required to cannot be limited to 100 V;
and
c)
quick-connect couplers that are not mechanically interlocked with a load-break-rated disconnect switch.
1.3 Application to non-mining structures
This Standard does not apply to tunnels, aqueducts, conduits, or excavations for civil construction
purposes. However, where mines incorporate such structures, this Standard applies.
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1.4 Structure of this Standard
Clauses 1 to 4 apply to all mines. The remaining clauses apply as follows:
a)
Clause 5 applies to surface mines and quarries;
b)
Clause 6 applies to underground mines; and
c)
Clause 7 applies to underground coal mines.
1.4 Clause numbering system
This Standard is divided into seven clauses, numbered from 1 to 7. Clauses are further divided into
subclauses (e.g., Clause 4.3). There can be up to five levels of subclauses (e.g., Clause 4.3.3.3.1).
Multiple items, designated by lowercase letters in parentheses (e.g., (a), (b), (c)) can be enumerated
in a list. If an item requires further listing, subsidiary items are identified by lowercase Roman
numerals in parentheses (e.g., (i), (ii), (iii)). Items in a further list under these subsidiary items are
identified by an Arabic numeral in parentheses (e.g., (1), (2), (3)).
Note: For further information see CSA-SDP-3.2.
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1.5 Inclusive lists and selective lists
The use of the conjunction “and” between two or more items in a sentence or list conveys an
inclusive relationship, i.e., all of the items or conditions in the list are included in the criteria (i.e., all
items present or conditions satisfied). The use of the conjunction “or” between two or more items in
a sentence or list conveys a selective relationship, i.e., at least one of the items or conditions in the list
is included in the criteria (i.e., a selective choice).
1.5 Terminology
In CSA Standards this Standard, “shall” is used to express a requirement, i.e., a provision that the
user is obliged to satisfy in order to comply with the Standard; “should” is used to express a
recommendation or that which is advised but not required; and “may” is used to express an option
or that which is permissible within the limits of the Standard.
Notes accompanying clauses do not include requirements or alternative requirements; the purpose
of a note accompanying a clause is to separate from the text explanatory or informative material.
Notes to tables and figures are considered part of the table or figure and may be written as
requirements.
Annexes are designated normative (mandatory) or informative (non-mandatory) to define their
application.
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2 Reference publications
This Standard refers to the following publications, and where such reference is made, it shall be to
the edition listed below, including all amendments published thereto.
CSA Group (Canadian Standards Association)
CAN/CSA-B72-M87 (R2008 R2013)
Installation code for lightning protection systems
B167-08 (R2015)
Overhead travelling cranes — Design, inspection, testing, maintenance, and safe operation
C22.1-09 15
Canadian Electrical Code, Part I
C22.2 No. 0.3-09 (R2014)
Test methods for electrical wires and cables
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CAN/CSA-C22.2 No. 0.17-00 (R2009 R2013)
Evaluation of properties of polymeric materials
C22.2 No. 25-1966 (R2009)
Enclosures for use in Class II Groups E, F and G hazardous locations
C22.2 No. 31-10 14
Switchgear assemblies
C22.2 No. 33-M1984 (R2009 R2014)
Construction and test of electric cranes and hoists
C22.2 No. 40-M1989 (R2014)
Cutout, junction, and pull boxes
CAN/CSA-C22.2 No. 94-M91 (R2006)
Special purpose enclosures
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CAN/CSA-C22.2 No. 94.1-07 15
Enclosures for electrical equipment, non-environmental considerations
CAN/CSA-C22.2 No. 94.2-07 15
Enclosures for electrical equipment, environmental considerations
C22.2 No. 96-09 13
Portable power cables
C22.2 No. 96.1-09 13
Mine power feeder cables
C22.2 No. 298-16
High voltage couplers
C22.2 No. 2556-15
Wire and cable test methods
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C22.3 No. 1-10 15
Overhead systems
C68.10-08 14
Shielded power cable for commercial and industrial applications, 5–46 kV
CSA-SDP-3.2-09
CSA Editorial requirements and guidelines
Z432-04 (R2009 R2014)
Safeguarding of machinery
CAN/CSA-Z460-05 13
Control of hazardous energy — Lockout and other methods
Z462-08 15
Workplace electrical safety
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Z463-13
Guideline on maintenance of electrical systems
BNQ (Bureau de normalisation du Québec)
CAN/BNQ 2910-500 (2015)
Explosives – Magazines for Industrial Explosives
CAN/BNQ 2910-510 (2015)
Explosives – Quantity Distances
IEC (International Electrotechnical Commission)
60079 Series
Explosive atmospheres
60079-0-11
Explosive atmospheres — Part 0: Equipment — General requirements
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IEEE (Institute of Electrical and Electronics Engineers)
Std 80-2000 2013
IEEE Guide for Safety in AC Substation Grounding
Std 400-2001 2012
IEEE Guide for Field Testing and Evaluation of the Insulation of Shielded Power Cable Systems
Std 450-2002 2010
IEEE Recommended Practice for Maintenance, Testing, and Replacement of Vented Lead-Acid Batteries for
Stationary Applications
Std C62.22-2009
IEEE Guide for the Application of Metal-Oxide Surge Arresters for Alternating-Current Systems
C62.22a-2013
IEEE Guide for the Application of Metal-Oxide Surge Arresters for Alternating-Current Systems —
Amendment 1: Supplement to Consider Energy Handling Capabilities
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Natural Resources Canada
G05-01:2014
Guidelines for Bulk Explosives Facilities — Minimum Requirements (2010)
Storage Standards for Industrial Explosives (2001)
G05-02:2011
Requirements for Mobile Bulk Processing Units
NETA (InterNational Electrical Testing Association)
ANSI/NETA MTS-2007 2011
Maintenance Testing Specifications for Electrical Power Distribution Equipment and Systems
NFPA (National Fire Protection Association)
70B (2010) 2016
Recommended Practice for Electrical Equipment Maintenance
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262 (2015)
Standard Method of Test for Flame Travel and Smoke of Wires and Cables for Use in Air-Handling Spaces
NRCC (National Research Council Canada)
National Building Code of Canada, 2005 2015
UL (Underwriters Laboratories Inc.)
94-1996 2013
Standard for Tests for Flammability of Plastic Materials for Parts in Devices and Appliances
Other publications
Beck, R.T., and L. Yu. 1988. Design considerations for Arctic grounding systems. IEEE transactions on
industry applications, 24: 1096–1100.
Gill, H.W. 1974. Design problems for an electric power system in an Arctic region. IEEE transactions on
industry applications, IA-10: 325–333.
Gill, P. 2009. Electrical power equipment maintenance and testing, 2nd ed. Boca Raton, FL: CRC Press.
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He, J., Gao, Y., Zeng, R., Sun, W., Zou, J., and Guanet, Z. et al. 2005. Optimal design of grounding
system considering the influence of seasonal frozen soil layer. IEEE transactions on power delivery, 20 (1):
107–115.
3 Definitions
The following definitions shall apply in this Standard:
Accredited certification organization — an organization that has been accredited by the Standards
Council of Canada in accordance with specific criteria, procedures, and requirements to operate, on
a continuing basis, a certification program for electrical equipment.
Approved (as applied to electrical equipment) —
a)
equipment that has been certified by a certification organization accredited by the Standards
Council of Canada in accordance with the requirements of a CSA Standard or another
recognized document (when an applicable CSA Standard does not exist); or
b)
equipment that meets the requirements of the authority having jurisdiction.
Authorized person — a qualified person who, in his or her duties or occupation, is obliged to
approach or handle electrical equipment, or a person who, having been warned of the hazards
involved, has been instructed or authorized to do so by someone having the authority to give the
instruction or authorization.
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Cable side-wall pressure — the force exerted on an electrical cable as it is pulled around a bend.
Electrically safe work condition — a state in which an electrical conductor or circuit part has been
disconnected from energized parts, locked out in accordance with established standards, tested to
ensure the absence of voltage, and grounded (if grounding is determined to be necessary).
Energized — electrically connected to or having a source of voltage.
Engineer — an engineer who has expertise in blasting and mine equipment and is licensed to
practice in a jurisdiction in Canada.
Equipment —
Fixed equipment — equipment that is not designed to be moved.
Hand-held equipment — equipment that has been designed to be held in the hand while
operating.
Mobile electrical equipment — equipment that is designed to be energized while moving.
Movable electrical equipment — electrical equipment that does not have its own grounding
network and is designed to be moved only when de-energized.
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Explosion-proof — enclosed in a case that is capable of withstanding, without damage, any
explosion of a specified gas or vapour that could occur within the case, and capable of preventing
the ignition of a specified gas or vapour surrounding the case by sparks, flashes, or an explosion of
the specified gas or vapour within the case.
Equipment protection level (EPL) — level of protection assigned to equipment based on its
likelihood of becoming a source of ignition and distinguishing the differences between explosive gas
atmospheres, explosive dust atmospheres, and the explosive atmospheres in mines susceptible to
firedamp.
Note: See the Canadian Electrical Code, Part I, Section 18 for additional definitions.
Fail-safe (when applied to an electrical-protection system) — the concept that the failure or
removal of any component, other than relay contacts, will not impede the function of the protection
system.
Note: Shunt-trip systems do not meet fail-safe requirements.
Flash point — the minimum temperature at which a liquid produces sufficient vapour to form an
ignitable mixture with air near the surface of the liquid or within the test vessel used.
Ground potential rise (GPR) — the maximum voltage that a station-grounding grid can attain
relative to a distant grounding point assumed to be at the potential of remote earth. The GPR is
equal to the maximum grid current times the grid resistance.
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Instantaneous — without intentional time delay.
Intake air — air that has not passed through any place of work and has not become contaminated
with mine gases.
Interlock — a device or system whereby the status of one control or mechanism allows or prevents
the operation of another.
Intrinsically safe — that any spark or thermal effect that can occur in normal use, or under any
conditions of fault likely to occur in practice, is incapable of igniting a specified flammable gas,
vapour, or dust.
Intumescent (paint) — a coating material (paint) that swells up when heated, protecting the
material underneath in the event of a fire.
Low voltage (as applied to equipment) — any voltage exceeding 30 V but not exceeding 750 V.
Mine — an excavation in the earth for the extraction of metal ore, minerals, coal, aggregates, or
other naturally occurring materials.
Surface mine (quarry) — a mine open to the surface of the earth (i.e., an open-air excavation).
Underground mine — a mine not open to the surface of the earth and having restricted
access from the surface through shafts, tunnels, or other relatively narrow passageways.
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Mine power feeder cable — an unarmoured, nonflexible cable that
a)
has a construction meeting the requirements of CSA C22.2 No. 96.1; and
b)
is suitable for use at a maximum conductor temperature of 90 °C under normal operating
conditions in wet or dry locations, outdoors or in underground mines, and in rugged
environments normally used for power distribution in stationary or semi-stationary
applications that are covered by this Standard and the Canadian Electrical Code, Part I.
Neutral-grounding device — an impedance device used to connect the neutral of an electrical
system to ground for the purpose of controlling ground current and voltage-to-ground.
Portable generator — electric generation equipment that is designed to be hand carried, is rated 240
V and less, and generally does not exceed 12 kW in output.
Portable power cable — a flexible cable that
a)
has a construction meeting the requirements of CSA C22.2 No. 96; and
b)
is suitable for use at a maximum conductor temperature of 90 °C under normal operating
conditions in wet or dry locations, outdoors or in underground mines, and in rugged
environments in applications where the cables are subject to frequent flexing and installation
is in accordance with this Standard or the Canadian Electrical Code, Part I.
Note: Portable power cable is sometimes referred to as “trailing cable”.
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Prospective ground-fault current of a system — the ground-fault current that flows from a phase to
a ground fault of zero impedance at rated system voltage under steady state conditions.
Protected by location (pertaining to equipment, including cables) — mounted in a location that
excludes the potential for damage.
Notes:
1)
“Damage” is usually used to mean mechanical damage, but a location can also provide protection from
excessive heat, water, etc.
2)
When physical protection of equipment is required, the alternative to protection by location is to
provide mechanical protection (e.g., in the case of cable, to use conduit, an enclosed wireway, etc.).
Qualified person (worker) — a person who has skills and knowledge related to the construction
and operation of electrical equipment and installations and has been trained to recognize and avoid
the applicable hazards.
Shunt tripping — a method in which the protection applies a voltage to the trip coil of the circuit
breaker. The voltage can be derived from the protected network or an independent source.
Tripping ratio — the ratio of prospective ground-fault current to the operating value of the groundfault protection.
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Undervoltage tripping — a method whereby a control device is tripped off-line using an
undervoltage release coil when the voltage of the main circuit is equal to or less than the release
setting.
Note: An undervoltage release coil can may also be used to trip a control device off-line if the control voltage is
equal to or less than the release setting.
Visible break (when applied to a disconnecting means) — a switch or device wherein the
separation between all members of the movable and the fixed current-carrying parts can be readily
determined by visual inspection.
Note: See Rule 2-304 of the Canadian Electrical Code, Part I.
Working on (energized electrical conductors or circuit parts) — coming in contact with energized
electrical conductors or circuit parts with the hands, feet, or other body parts, or with tools, probes,
or test equipment, regardless of the personal protective equipment a person is wearing.
Note: There are two categories of “working on”:
a)
diagnostic (testing): taking readings or measurements of electrical equipment with approved test
equipment that does not require making a physical change to the electrical equipment; and
b)
repair: physical alteration of electrical equipment, e.g., making or tightening connections or removing
or replacing components.
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4 General requirements
4.1 Application
4.1.1
Clause 4 applies to all types of mines unless otherwise specified in this Standard.
4.1.2
Electrical equipment used in mines shall be approved and of a type and rating approved for the
specific purpose for which it is to be employed. Approved electrical equipment shall comply with
the requirements of this Standard.
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4.2 Miscellaneous
4.2.1 Mine plans
4.2.1.1
Each mine in which electricity is used shall have a plan or single-line diagram showing the
a)
relative location of all fixed electrical distribution equipment;
b)
routes, properly noted and referenced, of all fixed power distribution feeders; and
c)
rating of all fixed electrical distribution equipment.
4.2.1.2
The plans and diagrams specified in Clause 4.2.1.1 shall be regularly reviewed and updated at a
frequency not less than that required by the authority having jurisdiction.
Note: Where the authority having jurisdiction does not specify a frequency for review and updating, plans
and diagrams should be reviewed and updated at least annually and after any significant change to the
electrical system.
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4.2.1.3
The plans and diagrams specified in Clause 4.2.1.1 shall be available to the authority having
jurisdiction at all times. Copies of the plans and diagrams shall be kept on site and furnished upon
request to the authority having jurisdiction.
4.2.2 Supervision and work
4.2.2.1
Only authorized persons shall work on or be in charge of electrical equipment or systems.
4.2.2.2
Only authorized persons shall undertake installations of and repairs, extensions, or changes to
electrical equipment or systems.
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4.2.3 Temporary installations
4.2.3.1
Switches or plug connectors shall be provided at the supply end of all temporary wiring.
4.2.3.2
Temporary wiring and equipment that is not in compliance with this Standard may be used only
during an emergency where
a)
danger to life or the safety of the mine is involved;
b)
authorized supervision is provided; and
c)
suitable barriers are installed and warning signs are effectively posted.
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4.2.4 Out-of-service wiring
4.2.4.1
Damaged or out-of-service wiring shall be disconnected from its source of power. Wiring left in
place shall be identified as out of service and shall have its bare conductors guarded.
Note: It is considered a best practice to include information that identifies the previous use of the cable, e.g.,
“Out of service — formerly fed from 69-abc circuit in xyz switch room”.
4.2.4.2
Overhead lines that are out of service shall be disconnected from the source of power, isolated, and
grounded.
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4.2.5 Work on energized equipment
4.2.5.1
Except in connection with work on overhead lines and the tasks specified in Clause 4.2.5.2,
energized conductors or circuit parts shall be put into an electrically safe work condition prior to
their repair or alteration.
Notes:
1)
In accordance with CAN/CSA Z460, work on overhead lines is required to be performed using
approved safe work methods that include other hazardous energy control methods approved by the
authority having jurisdiction.
2)
See Clause 7.3 for specific requirements related to electrical work in underground coal mines.
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4.2.5.2
Notwithstanding Clause 4.2.5.1, if adjustments, tests, calibrations, repairs, or alterations with respect
to electrical conductors or circuit parts cannot be performed in a de-energized state because of
equipment design or operational limitations, or de-energizing will introduce new hazards or
increase existing hazards, energized work may be performed. In these cases, all necessary
precautions consistent with the nature and extent of the hazards shall be taken to ensure that the
work can be performed safely.
Note: See Clauses 4.1.5 and 4.1.8 of CSA Z462 for guidance in establishing safety-related work practices
appropriate to the risk associated with electrical hazards. An example of a mining-related work practice that
could be developed is the safe manual handling of energized portable power cable.
4.2.5.3
Cable couplers for portable power cable operating at voltages exceeding 150 V to ground shall not
be coupled or uncoupled while energized.
4.2.6 Fire-extinguishing device
A fire-extinguishing device shall be provided for each electrical equipment room or vault. The
device shall be
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a)
approved for use on electrical fires (e.g., Class C);
b)
sized for the size and type of electrical equipment0;
c)
placed at an entrance to or exit from the area in a visible location;
d)
accessible without exposing the operator to undue risk; and
e)
maintained in a condition suitable for immediate use.
4.2.7 Notices to workers
Where a hazard exists from inadvertent access to or interference with electrical apparatus, durable
notice signs of sufficient size shall be effectively posted and
a)
prohibit unauthorized personnel from handling or interfering with electrical apparatus; (
b)
warn of danger and indicate the highest voltage in use;
c)
provide instructions for communication with the supervisor of the electrical equipment; (
d)
specify the procedure to be followed in case of electrical fire; and
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e)
contain directions for the procedures for rescuing persons in contact with energized electrical
conductors and resuscitating persons experiencing the effects of electrical shock.
The requirements specified in Items c) to e) shall not be obligatory where adequate mine emergency
procedures are in place.
4.3 Wiring methods
4.3.1 Cables
4.3.1.1 Cable jackets
Jackets on cables shall remain unpainted.
4.3.1.2 Identification
Notwithstanding Clause 4.3.1.1, and in association with Clause 4.3.3.5, an acceptable paint may be
used to apply a short length of colour for cable identification purposes on each end of a cable,
provided the paint is of a type that does not reduce the flammability characteristics of the cable
jacket (see Annex I) and each marking is applied not more than 150 mm wide along the length of the
cable. Intermediate markings along the cable length may also be applied provided the identification
marks are not closer than 10 m apart.
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Note: Users should contact the cable manufacturer to determine acceptable paints. An example of an
acceptable paint is an intumescent type.
4.3.1.3 Vertical versus horizontal
Cable installations shall be considered vertical if the cable is installed at an angle greater than 45°
from horizontal.
Note: Refer to the Canadian Electrical Code, Part I, Rule 12-120 for cable support requirements.
4.3.1.4 Vertical cables
Notwithstanding Clause 4.3.1.3, cables may be unsupported up to the manufacturer’s stated
maximum unsupported length where cable movement is necessary to facilitate normal operation of
the equipment (e.g., drills, cable excavators, draglines, etc.).
4.3.2 Portable and mine power feeder cables
4.3.2.1 Portable (trailing) power cables
Portable power cables shall
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a)
meet the requirements of CSA C22.2 No. 96;
b)
be type SHD, SHD-GC, or SHD-BGC if operating at voltages exceeding 750 V; and
c)
have a rated ampacity that meet the requirements of Clause 4.3.2.3.
4.3.2.2 Mine power feeder cables
Mine power feeder cables shall
a)
meet the requirements of CSA C22.2 No. 96.1;
b)
have a rated ampacity that meets the requirements of Table D.1 of CSA C22.2 No. 96.1;
Note: Table D.1 of CSA C22.2 No. 96.1 is based on Table 12A of the Canadian Electrical Code, Part
I.
c)
not be used with winding on a drum; and
d)
not be used as portable power cables.
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4.3.2.3 Ampacity
The ampacity of a single copper conductor or multiple conductors of a given size in a portable
power cable shall be
a)
a maximum current as specified in Table 1A;
b)
corrected by the applicable factor specified in Table 1B when the conductors are installed at
an ambient air temperature other than 30 °C;
c)
corrected by the applicable factor specified in Table 1C for conductor temperatures other than
90 °C; and
d)
corrected by the applicable factor specified in Table 1D when cables are used with one or
more layers wound on a drum.
Notes:
1)
The proper sizing of cable to feed a load should consider voltage drop down the length of the cable and
thermal heating of the cable, both of which are related to the demand factor of the load. See Rule 28-108
and particularly Subrules (2) and (3) of the Canadian Electrical Code, Part I, for additional
guidance on the application of demand factors.
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2)
In addition to considering the electrical properties required for an application, users also need to
consider the physical aspects of the installation and of the environment it will be used in, including but
not limited to cable deformation at supports and bends and the probability of impact from falling or
driven objects. For example, cables installed in vertical shafts where hoisting can take place are at a
higher risk of damage due to impacts from falling objects, and a choice of armoured cable in this
application will be expected to improve safety.
4.3.2.4 Equipment ground connection
In grounding the frame of equipment receiving power from a resistance-grounded system, separate
connections shall be used so that the ground-conductor-to-equipment-frame connection will be
included in the monitored ground-check loop.
4.3.3 Portable power cables (usage)
4.3.3.1 Cable fittings
Cables shall enter metal frames of motors, splice boxes, and electric compartments only through
acceptable termination fittings. Portable power cables shall be secured to machines to protect the
cables from damage and prevent strain on the electrical connections.
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4.3.3.2 Permanent splicing of cables
When permanent splices in portable power cables are made, they shall be
a)
mechanically strong, with adequate electrical conductivity;
b)
effectively insulated and sealed so as to prevent moisture penetration; and
c)
tested for continuity and insulation integrity by a qualified person before being placed into
service.
4.3.3.3 Use in cable tray
Portable power cable that carries the marking TC in addition to its basic type designation may be
used in cable tray. It shall be rated in accordance with Table 1A, applying any required correction
factors in accordance with Tables 1B to 1D. Where more than one multiple conductor cable is used
within a cable tray, they shall be spaced at least one cable diameter apart.
Notwithstanding the Canadian Electrical Code, Part I, Rule 12-2202, portable power cables shall be
allowed to transition from a cable tray to a normal mining use of such cable (e.g., onto the surface of
the ground, mounted along a wall), provided the cable is suitably supported in the transition area.
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Note: Canadian Electrical Code, Part I, Rule 12-2202 (2) allows cables marked TC to be used in cable tray
even though Table 19 (covering the conditions of use of various cable types) does not address the use of
portable power cable.
4.3.3.4 Protection of cables
4.3.3.4.1
Cables shall be routed to avoid damage. For surface applications, cables shall be kept visible by
being mounted on suitable markers at regular intervals throughout the cable route. In surface
applications or wet environments, cable couplers shall be suitably supported off the ground (or mine
floor) and at an elevation to prevent the ingress of moisture.
4.3.3.4.2
Wherever cables cross haulageways, or where equipment must pass the cables, cables shall be
isolated by elevation or be protected from crushing.
4.3.3.5 Identification of cables
Each cable assembly operating at a voltage exceeding 300 V shall be provided with a visible means
of identifying the equipment to which it is connected, or other means shall be established in
accordance with the mine’s safety procedures.
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Note: Cable identification by use of cable tags or by application of an acceptable paint (see Clause 4.3.1.2)
should not be used on portable power cables connected to movable or mobile equipment as damage to or loss of
the marking from movement of cables can lead to misidentification. Identification by colour can have
implications for personnel afflicted by colour blindness.
4.3.4 Shielding for cables supplying mobile electrical equipment
Notwithstanding Clause 4.3.2.1 b), portable power cables supplying mobile electrical equipment
operating at a voltage exceeding 150 V to ground shall be shielded.
4.3.5 Wiring of magazines and of areas for storing explosives and
detonators
4.3.5.1 General
All electrical equipment and wiring installed or used in magazines or in areas for storing explosives
or detonators that are not magazines shall comply with
a)
Zone 22 (formerly, the Class II, Division 2) hazardous location requirements of the Canadian
Electrical Code, Part I; and
b)
CAN/BNQ 2910-500.
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(b)
Natural Resources Canada’s Storage Standards for Industrial Explosives.
Note: See also Annex E.
4.3.5.2 Location of magazines
Explosives or detonator magazines on the surface shall be located
a)
at least 15 m from overhead lines and at least 100 m from electrical substations; and
b)
in accordance with CAN/BNQ 2910-510.
Note: Surface magazines are used for both surface and underground mines.
4.3.5.3 Lightning protection
Power lines supplying magazines shall be protected against lightning surges.
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4.3.6 Overhead supply lines
4.3.6.1
Electrical supply lines shall be installed in accordance with CSA C22.3 No. 1 or a standard specified
by the authority having jurisdiction.
4.3.6.2
The additional clearances specified in Clauses 5.3.1.1 and 5.3.1.2 of CSA C22.3 No. 1 shall apply to
overhead supply lines (see Clause B.2 of this Standard).
4.3.6.3
Notwithstanding Table 2 of this Standard and Clause 5.3.1.1 of CSA C22.3 No. 1, the minimum
vertical clearances specified in Table 2 shall, where haulage vehicles are frequently used, be
increased by the following (see Clause B.2 of this Standard):
a)
the amount by which the combined vehicle and load height exceeds 4.15 m;
b)
the amount of snow pack; and
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c)
the amount by which banked shoulders, crests, or road maintenance increase road elevation.
4.3.6.4
The vertical clearances specified in Clause 4.3.6.3 do not provide for the travelling of cranes, shovels,
drills, and other oversized equipment having unusual dimensions. The requirements of Clauses
4.3.6.5 and 4.3.6.6 relate to the movement of such special equipment underneath or alongside
energized supply lines, but shall not be used to establish clearances for working in the vicinity of
energized supply lines.
4.3.6.5
When special equipment (see Clause 4.3.6.4) is moved, and the equipment will encroach on the
minimum clearances specified in Table 3, the supply lines shall be isolated and grounded. When the
movement is under the supervision of qualified personnel, the clearances specified in Table 2 may
be used.
4.3.6.6
Personnel involved in the movement of special equipment (see Clause 4.3.6.4) in the vicinity of
energized overhead supply lines shall minimize the risk of electrical shock from accidental contact
by
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a)
operating the equipment from a position on the equipment that is not in direct contact with
earth;
b)
having all persons on the ground groundspeople and safety watchers maintain a safe standoff distance from the equipment;
c)
using only prearranged visual signals or radio communications. Hard-wired communication
systems shall not be used between the equipment and persons on the ground; and
d)
ensuring that only persons required for the move are directly involved.
4.3.6.7
Disconnecting means shall be installed as near as practicable to the point at the beginning of each
branch power line circuit. The disconnecting means shall be equipped or designed so that visual
observation can be used to determine that the disconnecting means is open.
4.3.6.8
Except where specially trained and equipped live-line crews are employed, overhead supply lines
shall be isolated and grounded before work is performed on them.
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4.3.6.9
An overhead power line shall not be regarded as de-energized for the purpose of working on it until
a qualified person has determined that the power line has been isolated and grounded.
4.4 Installation of equipment
4.4.1 Movable and mobile equipment
4.4.1.1
A circuit supplying mobile electrical equipment operating at a voltage exceeding 150 V to ground
shall have ground-fault protection and ground-conductor monitoring at the source of supply (see
Annex A).
4.4.1.2
A circuit supplying movable electrical equipment operating at a voltage exceeding 150 V to ground
shall have
a)
ground-fault protection; and
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b)
ground-conductor monitoring, if supplied by cable using quick-connect couplers.
4.4.1.3
Notwithstanding Clause 4.4.1.2, ground-fault protection and ground-conductor monitoring shall not
be required for low-voltage movable equipment if
a)
an external bonding conductor of equivalent ampacity to that of the supply cable ground
conductors is used to bond the equipment to the supply ground network; and
b)
no quick-connect cable couplers are used, except where mechanical interlocks are employed
with a disconnect switch to ensure that a cable plug cannot be pulled from an energized
receptacle (see Clause 4.4.2.3).
4.4.1.4
Submersible pumps operating at voltages exceeding 150 V to ground shall be supplied by shielded
portable power cable and have ground-fault protection and ground-conductor monitoring.
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Notes:
1)
Submersible pumps that are connected to fixed wiring systems in and around buildings and structures
and do not use cable couplers are not covered by this Clause (refer to the Canadian Electrical Code,
Part I, for such equipment).
2)
Down-hole pumps that are connected to fixed wiring systems, that are not moved while energized and
do not use cable couplers, are covered by the Canadian Electrical Code, Part I.
4.4.1.5
Shaft-sinking equipment operating at voltages exceeding 150 V to ground shall be supplied by
shielded portable power cable and have ground-fault protection and ground-conductor monitoring.
Note: Shielded portable power cable is now required for this application to enhance worker safety.
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4.4.2 Quick-connect cable couplers
4.4.2.1
Cable couplers with manufacturing date codes of Jan. 1, 2018 or later and operating at voltages
exceeding 750 V shall meet the requirements of CSA C22.2 No. 298.
4.4.2.2
A quick-connect coupler used to join portable power cables or a cable and a flange-mount receptacle,
operating at a voltage exceeding 150 V to ground, shall have
a)
a mechanical fastening arrangement to join the coupler, with a tensile strength greater than
that of the portable power cable;
b)
strain-relief devices suitable for the intended portable power cable; (
c)
a means to prevent the ingress of moisture;
d)
a means to mechanically lock the coupler where the circuit voltage exceeds 750 V; (
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e)
f)
a pin arrangement such that the
i)
ground conductor makes before and breaks after the phase conductors; and
ii)
ground-check circuit makes after and breaks before the phase conductors; and
ground-fault protection and ground-conductor monitoring at the source of supply.
4.4.2.3
Notwithstanding Clause 4.4.2.2, if a disconnect switch is mechanically or electrically interlocked
with a receptacle for a portable power cable plug, and if quick-connect couplers are not used
downstream, ground-fault protection and ground-conductor monitoring shall not be required.
4.4.3 Conveyor systems
4.4.3.1
An electrically driven conveyor shall have the following:
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a)
pull-cords (see Clause 4.4.3.2) for stopping the conveyor at accessible locations along the
conveyor. The pull-cords shall be within easy reach of persons at such locations;
b)
when the conveyor is started automatically by remote control, or when a portion or portions
of the conveyor are not visible from the operator’s position, a start-up warning device; and
c)
head, tail, drive, deflection, and tension pulleys guarded at any pinch point that is or can
become accessible.
Note: More than one start-up warning device might be required depending on the design and total length of
the conveyor.
4.4.3.2
A pull-cord required by Clause 4.4.3.1 shall
a)
operate a manual-reset-type switch that stops the conveyor;
b)
be designed and arranged so that it operates the associated switching device and generates
the emergency stop signal when
i)
the pull-cord is pulled in any direction;
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c)
ii)
a perpendicular pulling force of less than 200 N is applied to the pull-cord; and
iii)
a perpendicular deflection of the pull-cord of less than 400 mm occurs;
be able to withstand, without breaking, a tension force ten times greater than is necessary to
generate the emergency stop signal; and
d)
incorporate a visual indicator to show which device has been operated where more than one
switching device is necessary.
4.4.3.3
Circuits critical to personnel safety shall directly control their appropriate functions through an
electro-mechanical device independent of the solid state logic or by using a safety-related softwareand firmware-based controller.
4.4.3.4
Circuits controlled through electro-mechanical devices shall initiate the stop function through deenergization rather than energization of the control device (i.e., fail-safe).
Note: This provides a means of circuit control that is independent of system failure.
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4.4.3.5
Software- and firmware-based controllers used in place of electro-mechanical (hardware-based)
components with safety-related devices shall
a)
be designed so that any safety-related component or firmware failure shall
i)
lead to the shutdown of the system in a safe state; and
ii)
prevent subsequent automatic operation until the component failure has been
corrected;
b)
supply the same degree of safety achieved by using hardwired or hardware components in
accordance with Clause 8.2.5 of CSA Z432; and
Note: This degree of safety can be achieved using microprocessor redundancy, microprocessor
diversity, and self-checking.
c)
be approved for use as safety devices.
Note: Firmware is executive control program code provided by the manufacturer of a component in a
nonvolatile internal storage mode and is not changeable by the user.
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4.4.3.6
A belt conveyor that is either used underground or more than 15 m long and is installed in a
building or other closed-in structure shall be provided with a belt-slip detection device to stop the
drive motor in the event of belt blockage or slippage.
4.4.4 Overhead travelling cranes
Electric overhead travelling cranes shall meet the requirements of CSA B167 and CSA C22.2 No. 33.
4.4.5 Portable and movable generators
4.4.5.1 Portable generators
4.4.5.1.1
The frame of a portable generator shall not be required to be connected to a grounding electrode as
defined in Rule 10-700 of the Canadian Electrical Code, Part I, for a system supplied by the generator
under the following conditions:
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a)
the generator supplies only equipment mounted on the generator, or cord-and-plugconnected equipment through receptacles mounted on the generator, or both; and
b)
the non-current-carrying metal parts of equipment and the equipment grounding conductor
terminals of the receptacles are bonded to the generator frame.
4.4.5.1.2
Portable electrical tools and equipment connected to an ungrounded portable generator shall be
a)
of the double-insulated type and clearly marked as such; or
b)
supplied from a Class A ground-fault circuit interrupter.
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4.4.5.2 Movable generators
4.4.5.2.1
For a vehicle-mounted movable generator, the frame of the vehicle shall not be required to be
connected to a grounding electrode as defined in Rule 10-700 of the Canadian Electrical Code, Part I,
for a system supplied by a generator located on the vehicle under the following conditions:
a)
the frame of the generator is bonded to the vehicle frame;
b)
the normally non-current-carrying metal parts of equipment and the equipment grounding
conductor terminals of the receptacles are bonded to the generator frame; and
c)
the generator supplies
i)
only equipment located on the vehicle;
ii)
cord-and-plug-connected equipment through receptacles mounted on the vehicle; or
iii)
both equipment located on the vehicle and cord-and-plug-connected equipment
through receptacles mounted on the vehicle or on the generator.
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Note: Movable generators mounted on vehicles that provide a neutral conductor and are installed as different
systems supplying equipment and receptacles on the vehicle need the neutral conductor bonded to the
generator frame and to the vehicle frame. The non-current-carrying parts of the equipment need to be bonded
to the generator frame.
4.4.5.2.2
A movable generator that is not vehicle-mounted and operates at voltages exceeding 150 V to
ground or is rated in excess of 12 kW shall be connected to ground in accordance with Section 10 of
the Canadian Electrical Code, Part I.
Note: See the Canadian Electrical Code, Part I, for installation and grounding requirements for fixed
mounted generators.
4.4.5.3 Grounded conductor bonding
4.4.5.3.1
A system conductor that is required to be grounded by Rule 10-210 of the Canadian Electrical Code,
Part I, shall be bonded to the generator frame when the generator is a component of a different
system.
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Note: For grounding portable generators supplying fixed wiring systems, see Rule 10-206 of the Canadian
Electrical Code, Part I.
4.4.5.3.2
Portable and movable generators that are installed as different systems and provide a neutral
conductor (e.g., three-phase, four-wire delta connected or three-phase, four-wire wye connected,
single-phase 240/120 V) shall have the neutral conductor bonded to the generator frame.
4.5 Protection and control
4.5.1 Isolating switches
Identifying barriers shall be provided between circuits where two or more sets of open blade-type
isolating switches are installed adjacent to each other.
Note: The intent of this requirement is to clearly identify each set of isolating switches.
4.5.2 Closing by gravity
Devices shall be provided with stops or installed so that they will not close by gravity.
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4.5.3 Interlocking of isolating devices
4.5.3.1
A switch not capable of operating under load shall be interlocked with a switch or circuit breaker
that is capable of operating under load.
4.5.3.2
Where it is not practicable to comply with Clause 4.5.3.1, the isolating device shall be clearly and
permanently marked to warn of the danger and to minimize the chance that it will be operated
under load.
4.5.4 Protection and control of transformers
Suitable disconnecting means shall be installed in the primary circuit of each power and distribution
transformer or each bank of such transformers operating as a unit. Where transformers are operating
in parallel to feed a single circuit, disconnecting means shall also be installed in the secondary circuit
of each transformer.
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4.5.5 Testing and calibration of protection devices
Except for fuses, each protective device for an installation operating at a voltage exceeding 750 V
shall be tested to confirm that the device prevents the equipment from being operated in excess of its
rating. These tests shall be performed before initial use and after every three years of use, and the
results shall be documented.
4.5.6 Ground-fault protection
When ground-fault protection is required by this Standard, the supply shall be
a)
grounded through a neutral-grounding device that limits ground-fault voltage to 100 V or
less; and
b)
de-energized in less than 1 s if ground-fault current exceeds 20% of the prospective groundfault current (see Annex A).
Notes:
1)
If ground-fault protection and grounding are not required by this Standard, consult the Canadian
Electrical Code, Part I.
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2)
Ground-fault detection parameters other than ground-fault current may be used to meet this
requirement provided that they can be directly correlated (e.g., using Ohm’s law) to the equivalent
value specified for ground-fault current.
4.5.7 Ground-conductor monitoring
When ground-conductor monitoring is required by this Standard, the supply shall be de-energized
by a fail-safe circuit in less than 0.5 s, and a de-energized supply shall not become energized if the
a)
ground-check conductor opens;
b)
ground-return conductor opens; or
c)
ground-check conductor shorts to ground.
A ground-conductor monitoring system shall have an open-circuit voltage of less than 100 V and
shall continuously indicate ground-circuit continuity.
Note: Shunt-trip systems do not meet fail-safe requirements. Undervoltage release systems might meet failsafe requirements. Refer to Annex F.
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4.5.8 Hand-held equipment
All portable hand-held equipment that is supplied by a power cord shall be protected by a groundfault circuit interrupter of the Class A type, unless such equipment is double-insulated and so
marked.
4.5.9 Automatic reclosing of power circuits
Power circuits protected by automatic circuit breakers shall by default not have an automatic
reclosing function activated. Automatic reclosing functions may be activated only after a study of
the particular circuit demonstrates there will be no hazard to personnel or equipment if such a
function is activated.
4.6 Grounding
4.6.1 Circuit-opening devices in grounding conductors
A circuit-opening device may be used in the neutral-to-ground connection on a star-connected
generator when two or more generators are required to be operated in parallel. Procedures for
opening and closing the device shall be instituted to ensure operator safety.
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4.6.2 Neutral-grounding devices
A neutral-grounding device shall be
a)
continuously rated, except when ground-fault tripping is provided;
b)
connected as close as practicable to the supply neutral; and
c)
where the neutral grounding device is a resistor, monitored so as to de-energize the supply in
less than 60 s if the neutral-grounding device resistor opens.
4.6.3 Ground-fault indication
4.6.3.1
A device required by Rule 10-106(2) of the Canadian Electrical Code, Part I, shall be provided with
a)
short-circuit protection; and
b)
a disconnecting means such as a general-use switch.
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A ground fault shall be investigated and removed without delay.
4.6.3.2
When an audible or visible alarm is used to indicate a ground fault, it shall continue signalling to
indicate the fault until the fault is cleared.
4.6.4 Grounding in permafrost conditions
When system grounds are being installed in permafrost situations, careful study and soil resistivity
testing of the area shall be undertaken to ensure that the lowest ground resistance can be obtained.
The exceptions specified in Rule 36-306 of the Canadian Electrical Code, Part I, shall not apply to
permafrost conditions.
Notes:
1)
The use of chemical ground rods can assist in reducing ground resistance.
2)
Backfill materials such as bentonite (a conductive clay) can assist a regular drilled-in ground rod to
maintain conductivity along the entire length of the embedded rod to ground.
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3)
Extra-long (deep) drilled-in ground rods can be necessary to reduce ground resistance to an acceptable
value.
4)
Oversized ground cable connecting the ground rods to the equipment or structures being protected can
be necessary. All joints should be engineered for lowest resistance (e.g., welded).
5)
See also Gill (1994 1974), Beck and Yu (1988), and He, et al. (2005).
4.7 Electric blasting
4.7.1 General
4.7.1.1
Clause 4.7 applies to the use of electricity for blasting supplied from the power distribution system.
4.7.1.2
The mine shall have procedures to prevent inadvertent detonation of electric blasting caps in the
presence of radio transmitters or other radio-frequency fields (e.g., from cellular phones, GPS
devices, and portable hand-held radios).
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4.7.1.3
Electric blasting circuits shall be tested for continuity before a blast is set off.
4.7.2 Supply characteristics
An isolated, ungrounded power source shall be used for electric blasting. It shall have adequate
capacity for the number of caps involved and be used for blasting only.
4.7.3 Conductors
4.7.3.1
Blasting-circuit conductors shall be
a)
made of not less than No. 12 AWG copper wire;
b)
without splices, as far as practicable; and
c)
readily identifiable as being for blasting use (and should be coloured red).
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4.7.3.2
Where expendable connecting wires are used from the lead wires to the leg wires of the blasting
caps, they shall be not less than No. 20 AWG.
4.7.4 Stray current precautions
4.7.4.1
Blasting-circuit conductors shall be kept at least 150 mm away from power or lighting cables and,
where possible, shall be run on the side of the working opposite power and lighting circuits.
4.7.4.2
Where blasting lines are installed for a short time only, they may be fastened to sprags or sticks for
adequate support.
4.7.4.3
Blasting-circuit conductors shall not come into contact with pipes, rails, or other electrically
conductive materials that might be accidentally energized or vulnerable to static charges.
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4.7.5 Control
4.7.5.1
A fused service switch with provision for locking shall be installed between the source of power and
the blasting switch.
4.7.5.2
When a blasting switch is used, a lightning gap of not less than 1.5 m shall be provided between the
service switch and the blasting switch, and the gap shall be closed only at the time of blasting by a
means such as a twist-type locking device.
4.7.6 Blasting switch
4.7.6.1
The blasting switch shall be constructed so that gravity tends to open the circuit and short the
blasting leads. When the power source exceeds 300 V, the blasting switch shall be electromagnetically operated.
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4.7.6.2
The blasting switch shall be placed within a fixed and locked box and accessible only to the
authorized blaster.
4.7.7 Multiple blasting
When a single blasting switch is used for several blasting circuits, a three-way isolating switch that
can be locked in either the shorted or closed position shall be installed in each circuit to provide for
shorting, energizing, and testing the circuit. Isolating switches shall be located in a safe place.
4.7.8 Maintenance
Permanent blasting lines, blasting switches, and service switches shall be maintained by a qualified
person.
4.7.9 Programmable logic control (PLC)
When a PLC or computer is used to control or initiate the blast, the system shall be approved by an
engineer in addition to meeting the requirements of Clauses 4.7.3.1 and 4.7.4.1.
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4.8 Lightning protection
4.8.1 General
Lightning protection should be provided in accordance with the requirements of IEEE Std C62.22, as
amended by IEEE C62.22a, except as otherwise specified in Clauses 4.8.2 to 4.8.4.
Note: Provisions for lightning protection includes lightning arresters, surge capacitors, high-speed protective
gaps, guard wires, guard structures, and air terminals.
4.8.2 Overhead lines
4.8.2.1
Where power feeders serving underground workings are connected to overhead lines longer than 90
m, lightning arresters or surge capacitors shall be installed at the point of connection to the
underground feeders.
4.8.2.2
Where overhead lines supply equipment on the surface, lightning arresters or surge capacitors shall
be installed at the interconnection.
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Notes:
1)
Lightning arresters should be located as close as practicable to the equipment being protected. This
helps to keep the arrester grounding conductors as short as possible in order to limit the voltage rise
during a lightning event.
2)
For arresters protecting equipment such as transformers, dead-tank circuit breakers, or cables, the
ground side of the arrester should be directly connected to the transformer or circuit breaker tank or
cable sheath to reduce as much as possible the voltage rise along the arrester ground. If it is connected
only to a ground rod or mat, the resulting voltage rise can be unacceptably high.
3)
The location where an overhead lightning-protection wire is connected to ground can affect the level of
transferred potential to movable and mobile equipment on the surface.
4.8.2.3
If ungrounded, the overhead lines specified in Clause 4.8.2.2 shall be provided with
a)
an overhead lightning-protection wire connected to ground electrodes at suitable intervals
along the line; or
b)
lightning arresters and/or surge capacitors connected at suitable intervals, including high
points, sharp bends, and dead ends.
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Note: “Suitable” in this context is determined by system design calculations.
4.8.2.4
Where ungrounded overhead lines traverse an area higher in elevation than the sites on any mine
property that they interconnect, and where natural conditions require such measures,
a)
an overhead lightning-protection wire with supplementary ground electrodes at the high
points shall be provided; or
b)
supplementary lightning arresters and/or surge capacitors shall be connected at suitable
intervals at the high points.
Note: “Suitable” in this context is determined by system design calculations.
4.8.3 Guard wires or structures
Where mine headframes, pipe services, tracks, cables, or other such nonsystem conductors that enter
the mine are in danger of being struck or charged by lightning, such services shall be protected at
the surface by lightning-protection wires or structures grounded by low-resistance grounds.
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4.8.4 Headframes
Mine headframes shall be protected in accordance with CAN/CSA-B72.
Note: Even though CAN/CSA-B72 is intended to be used for buildings and structures, it is appropriate for
use with mine headframes.
4.9 Radio-controlled equipment
Where radio-frequency equipment is used to remotely control machines, cranes, or other devices,
a)
the transmitter and receiver shall be designed as a matched set, such that the receiver
responds to a unique signal from its matched transmitter;
b)
procedures shall be implemented to ensure that the transmitter and receiver are correctly
matched as a unique set; and
c)
one transmitter shall control only one receiver.
Note: See also Clause 4.7.1.2.
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4.10 Safety-related maintenance
Electrical equipment shall be maintained to ensure that worker safety is not compromised.
Notes Note:
1)
Clause 5 of CSA Z462 provides practical safety-related maintenance requirements for electrical
equipment and installations in the workplace. These are available for use by organizations that do not
have a safety-related maintenance program.
2)
CSA Z463 provides direction for organizations seeking to design and implement an effective electrical
maintenance program. Refer to Annex D.
4.11 Outdoor electrical equipment — Fence enclosures
4.11.1 General
Fencework for guarding electrical equipment shall be constructed and installed in accordance with
Section 26 of the Canadian Electrical Code, Part I.
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4.11.2 Maintenance
Material shall not be stored against fencework and enclosures shall be maintained in a condition free
from run-off water, sloughing of debris, and vegetation growth.
5 Surface mines and quarries
5.1 Application
Clause 5 covers requirements for surface mines and quarries. These requirements are in addition to
those specified in Clause 4.
5.2 Electrical equipment rooms
5.2.1 General
The location, construction, and installation of a room containing electrical equipment shall ensure
the best practical protection against fire propagation, water and dust ingression, and corrosive
atmospheres. Electrical rooms shall be sufficiently ventilated to maintain equipment at safe
temperatures.
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5.2.2 Illumination
Lighting levels shall be sufficient to enable all equipment to be clearly distinguished and all
instruments and labels to be easily read. Where a personnel hazard would be caused by a failure of
the lighting system, an emergency lighting system shall be provided.
5.3 Movable switch houses and substations
5.3.1 Primary connections to a movable switch house or substation from
overhead supply lines
The following requirements shall apply to primary connections to a movable switch house or
substation from overhead supply lines:
a)
Cable connections to overhead supply lines shall terminate at a disconnecting means located
on a pole.
b)
The interconnecting cable length shall not exceed 25 m unless
i)
the ampacity of the cable is at least one-third of the overcurrent protection setting of
the supply; or
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ii)
properly sized overcurrent protective devices are installed at the point of cable
termination to the overhead line.
c)
The conductors of the cable shall be continuous and shall either
i)
be directly connected to the supply terminals of the switch house or substation.; or
ii)
terminate at a clearly labelled quick-connect cable coupler that shall only be energized
when properly and fully connected to an appropriate quick-connect coupler power
inlet integral to a switch house or substation and that is mechanically secured to that
power inlet with an interlock to the overhead supply lines feeding the switch house or
substation to ensure that the cable coupler and power inlet cannot be connected or
disconnected while the cable supply is energized.
d)
Intermediate cable couplers or junction boxes shall not be used in the supply line to a
movable switch house or substation.
5.3.2 Movable switch houses
Substructure construction shall be suitable for moving the switch house over rough terrain, or the
switch house shall be fitted with adequate lifting attachments to allow lifting onto other transport.
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Switch house enclosures shall meet the Type 3 requirements of CAN/CSA C22.2 No. 94.2. Each
switch house enclosure shall be grounded by a station-ground electrode that meets the requirements
of Rule 36-302 of the Canadian Electrical Code, Part I. Where Rule 36-302(3)(a) of the Canadian Electrical
Code, Part I, applies, only one grounding conductor shall be required to connect the station-ground
electrode to the movable switch house.
Switch houses shall also meet the following requirements:
a)
Except where drawout switchgear is used, the disconnecting means shall be of the manually
operated, three-phase, ganged, visible-blade type. It shall be suitably rated, installed at the
point of power entry, and key-interlocked with the circuit breaker or interrupter.
b)
The circuit breaker shall be complete and include all devices necessary to provide overcurrent
and ground-fault protection.
c)
Control devices requiring adjustment or resetting shall not be located inside the high-voltage
section of the switch house enclosure.
Note: Existing enclosures may be certified to CAN/CSA-C22.2 No. 94 rather than CAN/CSA-C22.2 No.
94.2.
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5.3.3 Movable substations
5.3.3.1 General
A substation consisting of an assembly of electrical equipment mounted on a self-supporting
movable structure or structures shall meet the following requirements:
a)
The self-supporting structure or structures shall be suitable for moving over rough terrain or
shall be fitted with adequate lifting attachments to allow lifting onto other transport.
b)
The power transformer shall be of the totally enclosed type or enclosed within a chain-link
fence that meets the requirements of the Canadian Electrical Code, Part I. A sign that reads
”DANGER: HIGH VOLTAGE” and “DANGER : HAUTE TENSION” and states the voltage
shall be posted at the entrance to the transformer enclosure.
c)
A substation assembly consisting of two or more movable structures interconnected by cable
shall be provided with a circuit breaker that trips the supply in the event of a ground fault on
the interconnecting cable. The length of the interconnecting cable shall not exceed 5 m.
d)
A neutral-grounding device shall be mounted as close as practicable to the transformer
neutral. Insulated cable more than 2 m long that connects the transformer neutral and
grounding device shall be protected by elevation or enclosure.
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5.3.3.2 Station-ground electrode
Each movable substation shall be grounded to a station-ground electrode that meets the
requirements of Subrules (1), (2), and (3) of Rule 36-302 of the Canadian Electrical Code, Part I. Where
Rule 36-302(3) (a) of the Canadian Electrical Code, Part I, applies, only one grounding conductor shall
be required to connect the station-ground electrode to the movable substation.
5.3.3.3 Station-ground resistance
The station-grounding system shall be designed and installed in a way that prevents the transfer of
potentials exceeding 100 V from the station-ground electrode to any connected movable or mobile
electrical equipment. The resistance of the station-ground electrode shall be measured and the
ground-fault protection shall be tested after installation or relocation of the substation. Changes shall
be made, if necessary, to ensure that the ground potential rise GPR will not exceed 100 V (see Annex
A).
5.4 Mobile electrical equipment
5.4.1 Scope
The requirements of Clause 5.4 apply to electrical installations on board mobile electrical equipment
using externally supplied power at voltages exceeding 100 V. Trolley systems are excluded.
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5.4.2 Miscellaneous
5.4.2.1 Fire-protection equipment
Fire alarm and fire-extinguishing equipment shall meet the requirements of Clause 4.2.6, except for
locations where fighting a fire is an unacceptable hazard, in which case
a)
an automatic fire-suppression system shall be provided; and
b)
signs instructing employees how to proceed in the event of a fire shall be posted at all points
of access to the area.
5.4.2.2 Locking and tagging of switches
Each circuit operating at a voltage exceeding 300 V, or each motor circuit fed from a service panel at
a voltage exceeding 100 V, shall provide for locking and tagging of the disconnecting means.
5.4.2.3 Illumination
The level of lighting in all areas of mobile electrical equipment shall be sufficient for the safe and
efficient performance of all required operation and maintenance functions.
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Emergency lighting shall be supplied for all areas of the equipment to ensure that all egress
walkways, stairways, and emergency exits are adequately illuminated for at least 30 min after loss of
main lighting power.
5.4.3 Wiring methods
5.4.3.1 Primary supply system
5.4.3.1.1 Grounding slip ring
The system-grounding conductor supplied to revolving-frame equipment through the trailing
portable power cable shall be connected to the revolving frame through a grounding slip ring.
5.4.3.1.2 Ground-check slip ring
To monitor continuity of the ground circuit to the upper frame of revolving-frame equipment, an
insulated ground-check conductor shall be wired through an insulated ground-check slip ring.
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5.4.3.2 Conductors
5.4.3.2.1 General
Cables should be sufficiently flexible to prevent damage during installation in confined spaces and
to withstand the shocks, vibrations, and temperature changes typical on mobile mining equipment.
Where power cables will be exposed to oils and chemicals, the cables shall be protected with
insulation or durable jacket material that is resistant to oils and chemicals. Where unjacketed metal
armour is used for mechanical protection, oil and chemical resistance may be provided by the
conductor insulation or jacket material under the armour.
5.4.3.2.2 Flame test rating Fire retardance
At a minimum, cables shall meet the FT1 rating requirements (see Annex I) specified in CSA C22.2
No. 0.3 96 when tested in accordance with the FT1 flame test in CSA C22.2 No. 2556. The jacket of a
nonmetallic covered cable shall not be surface-coloured or painted with any material that impairs
the flame-retardant properties of the jacket.
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5.4.3.2.3 External portable power cables
Notwithstanding Clause 5.4.3.2.2, portable power cables that terminates at mobile equipment but on
the outside (e.g., cable coupler, machine mounted junction box, cable reel) shall not need to have a
flame test rating.
5.4.3.3 Motor circuit wiring
There shall be separate disconnecting means, overload protection, and ground-fault protection for
each motor or group of motors. Specialized drives shall be exempt from this requirement.
5.4.3.4 On-board ac supply circuits
5.4.3.4.1 Resistance grounding
Where on-board three-phase power transformers larger than 20 kV•A and operating at voltages
exceeding 150 V to ground are used, the following requirements shall apply:
a)
Except as permitted by Item g), either a direct or derived neutral shall be grounded through a
resistor at the power source to limit the prospective ground-fault current to 25 A or less.
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b)
A grounding circuit shall originate at the grounded side of the resistor and extend along with
the power conductors to ground the frames of all electrical apparatus supplied from the
circuit, except where the steel structure provides the ground-return path as permitted by
Clause 5.4.5 b).
c)
The size of the grounding conductors may be reduced, provided that the ampacity exceeds
the prospective ground-fault current.
d)
Neutral-grounding resistors shall be isolated by elevation or guarded in accordance with
Clause 5.4.4.1.
e)
Neutral-grounding resistors shall be rated and protected in accordance with Clause 4.6.2.
f)
Ground-fault protection with a minimum tripping ratio of five shall be provided, except as
permitted by Items g) and h).
g)
Ungrounded systems with ground-fault detection may be used for specialized drive circuits.
h)
Ground-fault detection that alerts the operator to the ground fault may be used instead of
ground-fault protection where de-energizing a circuit can create a machine operation hazard.
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5.4.3.4.2 Primary-circuit isolation
Isolation of on-board incoming circuits shall be provided by
a)
a load-break disconnecting means supplied directly from the slip rings or incoming
connection chamber of the machine;
b)
an interlocked, no-load disconnecting means supplied directly from the slip rings or
incoming connection chamber. The interlock shall be arranged to ensure that the isolator
cannot be operated under load; or
c)
a load-break disconnecting means or suitably interlocked no-load disconnecting means for
each primary-voltage circuit on board the machine.
5.4.3.5 120 V Receptacles
Each receptacle rated less than 150 V to ground 120 V outlet or its supply circuit shall be equipped
with an approved protected by a ground fault circuit interrupter of the class A type.
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5.4.4 Installation of equipment
5.4.4.1 Guarding of energized parts
5.4.4.1.1
Except in electrical equipment rooms accessible only to authorized persons, energized parts of
electrical apparatus operating at voltages exceeding 30 V ac or 42 V dc shall
a)
be guarded to prevent contact with any person standing at floor level. Guards shall not have
openings that permit contact with energized parts by any person standing at floor level using
a hand-held probe, as specified in CSA C22.2 No. 31; and
b)
have signs posted to warn workers of an electrical hazard if energized parts can be accessed
from ladders or elevated platforms.
5.4.4.1.2
In electrical equipment rooms accessible only to authorized persons, energized parts of electrical
apparatus operating at voltages exceeding 30 V ac or 42 V dc, or control relays operating at voltages
exceeding 150 V, shall be
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a)
guarded to prevent accidental body contact; or
b)
isolated by a minimum elevation of 2.5 m, and for voltages above 2.5 kV, by elevations in
accordance with Table 32 of the Canadian Electrical Code, Part I.
5.4.4.2 Switchgear
Switchgear containing more than 23 L of liquid that has a flash point less than 275 °C shall be
installed in enclosed, separate compartments.
5.4.4.3 Transformer rooms
Fire spread from liquid-filled transformers shall be controlled by providing
a)
an enclosed, separate compartment to contain any liquid that could be released and any fire
that could occur;
b)
a drainage system to ensure that any fire that could occur can be safely controlled; or
c)
an approved automatic fire-suppression system.
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5.4.4.4 Fuse identification
A durable sign clearly indicating the correct fuse type and rating shall be posted at each fuse
location.
5.4.5 Grounding
The following grounding requirements shall apply:
a)
General grounding and bonding of electrical apparatus on board mobile electrical equipment
shall be in accordance with the Canadian Electrical Code, Part I.
b)
The metal structure of mobile electrical equipment may be used in lieu of a groundingconductor connection to electrical apparatus. Bonding straps shall be used if structural
bonding is inadequate.
c)
Where any revolving machine section is supplied with power through slip rings, a systemgrounding conductor shall also be connected to the section through a grounding slip ring.
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5.4.6 Access control to high-voltage equipment
Access to the portable power cable connection compartment, slip-ring compartment, and
compartments or enclosures of other primary high-voltage equipment in which energized parts are
not isolated by elevation or guarded in accordance with Clause 5.4.4.1 shall be controlled by
a)
a mechanical or key interlock to ensure that access is available only after the power supply
has been isolated from the machine;
b)
substantial steel cover plates affixed by a multi-bolt system requiring the use of hand-held
tools to release. Each cover plate shall carry the warning, “DANGER: ISOLATE ELSEWHERE
ALL ENERGY SOURCES BEFORE REMOVING THIS COVER” and “DANGER : ISOLER
TOUTES LES SOURCES D'ÉNERGIE AVANT DE RETIRER CE COUVERCLE”, and shall be
interlocked in such a manner that its removal will cause the power supply to the machine to
be de-energized and will not allow the power to be restored until the cover plate is replaced;
or
c)
a padlock configuration that ensures access only to authorized personnel.
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5.4.7 Protection and control devices
5.4.7.1 Control of power source
A control push button or switch that trips the remote-source circuit breaker shall be readily
accessible to the operator.
5.4.7.2 Emergency stop
An emergency stop control device shall be provided on the operator’s console to ensure that the
machine can be safely and quickly stopped in an emergency.
5.4.7.3 Mechanical brakes
All main motions of mobile electrical equipment shall have mechanical brakes that apply
automatically in the event of a power failure.
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5.4.7.4 Regenerative feedback
Where applicable, an instantaneous device shall be incorporated into the circuitry to prevent
regenerative feedback into the portable power cable following main power supply interruption.
Undervoltage tripping devices shall not be used for this purpose.
6 Underground mines
6.1 Application
Clause 6 covers requirements for underground mines. These requirements are in addition to those
specified in Clause 4.
6.2 Electrical equipment rooms
The location, construction, and installation of a room containing electrical equipment shall ensure
the best practical protection against fire propagation, water and dust ingression, and corrosive
atmospheres. Electrical rooms shall be sufficiently ventilated to maintain equipment at safe
temperatures.
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6.3 Wiring methods
Note: Given the numerous types of cables available, the user should consult the manufacturer for cablespecific installation criteria. This Clause specifies minimum safety factors and installation criteria.
6.3.1 Conductors
6.3.1.1 General
Conductors, cables, or portable power cables supplying power to fixed equipment at voltages-toground exceeding 150 V shall be protected by armour, conduit, or a similar mechanical means, or
protected by location.
6.3.1.2 Support for horizontal cables
Where installation is predominantly horizontal, conductors or cables shall be supported at intervals
of not more than 1.5 m throughout the run. Strain relief shall be provided within 300 mm or as close
as practicable at each box, coupler, or fitting.
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6.3.1.3 Support for vertical cables
6.3.1.3.1
The portion of conductors or cables whose installation is predominantly vertical shall be supported
at intervals as specified in Table 21 of the Canadian Electrical Code, Part I. Strain relief shall be
provided within 300mm or as close as practicable at each box, coupler, or fitting.
6.3.1.3.2
Notwithstanding Clause 6.3.1.3.1, for the purpose of moving the work platform away from the
working or blast face at the bottom of the shaft, portable power cables being installed while shaft
sinking may hang unsupported for a distance not exceeding the lesser of
a)
the maximum unsupported length as calculated by Clause 6.3.1.11; or
b)
the manufacturer’s stated maximum unsupported length.
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6.3.1.4 Support for mine-shaft cables
The portion of conductors or cables installed in a mine shaft shall be supported at intervals in
accordance with the manufacturer’s instructions and in no case at intervals of not more than 10 m.
Portable power cables used for shaft sinking may be supported in accordance with Clause 6.3.1.3.2.
6.3.1.5 Support for borehole cables
Notwithstanding Clause 6.3.1.4, borehole cables may be supported by a single-point suspension
with a minimum safety factor of 5. Intermediate vertical cable supports shall have a safety factor of
5.
Note: Intermediate cable support loads should be calculated based on per unit weight of the cable (total
suspended load) and standard working load capacity of the cable supports.
6.3.1.6 Mine-shaft cable design
Mine-shaft cables shall be of a mechanical design that
a)
provides armour or equivalent mechanical protection to protect the insulated phase
conductors;
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b)
is suitable for vertical suspension for the distance of the intended rise;
c)
does not permit slippage of any internal component relative to another; and
d)
does not result in the cable weight being supported by the electrical conductors within the
cable after installation.
6.3.1.7 Mine-shaft cable installation pulling procedure
Mine-shaft cables should may be installed by being pulled up from below and without exceeding
cable , or lowered from the top. Cable manufacturer’s side-wall pressure limits developed as a result
of deviation from vertical while pulling shall not be exceeded.
Note: Hazards associated with vertical cable installation within mines, such as loss of control if unreeling
from the top, should be controlled using risk management practices and development of safe work plans prior
to installation.
6.3.1.8 Mine-shaft cable pulling tension safety factors
Unless otherwise required in cable manufacturer's installation instructions that exceed the following,
mine-shaft cable pulling safety factors for shaft and borehole installations shall be not less than
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a)
5 when Mineshaft cable being pulled solely by round steel armour wires armouring or
dedicated tensile pulling members; and shall have a safety factor of not less than 5 for shaft
and borehole installations.
b)
7 when being cable is pulled solely by electrical conductors serving as tensile pulling
members, the safety factor shall not be less than 7.
Cable installations shall not be performed by simultaneously pulling a combination of tensile
members composed of dissimilar materials.
When cables are clamped as the reel descends, the safety factor shall be not less than 5 between
clamps.
6.3.1.9 Use of galvanized steel round or flat wire armour wires as tensile
pulling members
Unless otherwise required in cable manufacturer's installation instructions that exceed the following,
the maximum vertical pulling length for mineshaft cable using round galvanized steel round or flat
wire armour wires as tensile pulling members shall be determined in accordance with the following
equation:
Lmax = (A × Ts) / (F × W)
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where
Lmax =
maximum vertical pulling length, ft
A
=
total cross-sectional area of the round steel armour wires, in2
Ts
=
tensile strength of the round steel armour round or flat wires, lb/in2
F
=
safety factor (5 minimum)
W
=
weight of the cable, lb/ft
Note: This equation is taken from Annex D of CSA C68.10.
6.3.1.10 Use of built-in or similar dedicated tensile pulling members
Unless otherwise required in cable manufacturer's installation instructions that exceed the following,
the maximum vertical pulling length for steel interlocked metal tape armour or continuously
corrugated sheath mineshaft cables using built-in or similar tensile pulling members (e.g., steel
messenger wire) shall be determined in accordance with the following equation:
Lmax = (N × Ts) / (F × W)
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where
Lmax =
maximum vertical pulling length, ft
N
=
total number of dedicated tensile members
Ts
=
tensile strength of one dedicated tensile member, lb/in2
F
=
safety factor (5 minimum)
W
=
weight of the cable, lb/ft
Note: This equation is taken from Annex D of CSA C68.10.
6.3.1.11 Use of electrical conductors as tensile pulling members
Unless otherwise required in cable manufacturer’s installation instructions that exceed the
following, the maximum vertical pulling length for mineshaft cable using electrical phase
conductors as tensile pulling members shall be determined in accordance with the following
equation:
Lmax = (N × Ts × A) / (F × W)
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where
Lmax =
maximum vertical pulling length, ft
N
=
total number of electrical phase conductors
Ts
=
tensile strength of one phase conductor, lb/in2 (24 000 lb/in2 standard annealed copper)
A
=
area of one conductor, in2
F
=
safety factor (7 minimum)
W
=
weight of the cable, lb/ft
Note: This equation is taken from Annex D of CSA C68.10.
6.3.1.12 Use of cables subject to core slippage in vertical pulls
When cable designs subject to core slippage for vertical pulls are used, the vertical height shall not
exceed 22 m installation shall comply with the Canadian Electrical Code, Part I, Rule 12-120 (4).
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6.3.2 Flame testing test rating
6.3.2.1
Power cables installed in a mine shaft or escapeway shall meet the FT4 rating requirements (see
Annex I of this Standard) specified in CSA C22.2 No. 2556 0.3. The maximum permitted char shall be
1500 mm.
6.3.2.2
Notwithstanding Clause 6.3.2.1, portable power cables used in shaft sinking operations at voltages
exceeding 150 V to ground shall not be required to have an FT4 rating.
6.3.2.3
Portable power cables shall meet the FT5 rating requirements specified in CSA C22.2 No. 0.3 96
when tested in accordance with CSA C22.2 No. 2556.
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6.3.2.4
Mine power cables without armour jackets shall meet the FT5 rating requirements specified in CSA
C22.2 No. 0.3 96.1 when tested in accordance with CSA C22.2 No. 2556.
6.3.2.5
Mine power cables with armour jackets shall meet the FT4 rating requirements specified in CSA
C22.2 No. 0.3 2556.
6.3.2.6
Cables other than those specified in Clauses 6.3.2.1 to 6.3.2. 5 shall meet the FT1 rating requirements
specified in CSA C22.2 No. 0.3 2556.
6.3.3 Splices
When a an in-line splice is made in a cable or conductor used in a shaft or winze at a voltage
exceeding 750 V,
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a)
the splice shall have electrical and mechanical characteristics equivalent to that of the cable
and shall not result in tension on the connections due to core slippage;
b)
the cables shall be secured to the shaft walls at no more than 1 m above and below the splice;
c)
the splice shall be made by an authorized person; and
d)
the splice and cable shall be subjected to a high-potential test or other recognized dielectric
test methods as recommended by the cable manufacturer.
6.3.4 Junction boxes
Note: The junction boxes referred to in this Clause are not the types of junction boxes covered by CSA C22.2
No. 40.
6.3.4.1
A junction box used where the circuit voltage exceeds 750 V shall be at least 3 m from the shaft.
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6.3.4.2
A junction box used in a shaft where the circuit voltage is 750 V or less shall meet the Type 4
requirements of CAN/CSA C22.2 No. 94.1 and the type 4 requirements of CAN/CSA C22.2 No. 94.2.
6.3.4.3
A Nonmetallic enclosure may enclosures installed underground shall not be installed underground,
except in a mine shaft or escapeway. if the enclosure material meets Nonmetallic enclosures installed
underground shall meet classification 0.6 V-0 of CAN/CSA-C22.2 No. 0.17 or classification 94-5V of
UL 94.
6.4 Installation of transformers and capacitors
6.3.1 Surface transformers — Flash point less than 275 °C
A transformer that contains a liquid with a flash point less than 275 °C and is installed on the surface
in the vicinity of the escapeway or entrance to an underground mine
a)
shall be located at least 15 m from a headframe, shaft house, portal house, adit, or
combustible building attached to such a structure;
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b)
shall be mounted on a noncombustible pad designed to contain the liquid from the largest
transformer and prevent spill from seeping into and entering the mine, headframe, shaft
house, portal house, adit, or other building; and
c)
may be located beside a fireproof building that is attached to the headframe, shaft house,
portal house, or adit if there are no openings in the part of the building adjacent to the
transformer through which smoke or heat can enter the building.
6.4.2 Underground transformers — General
A transformer installed in an underground mine shall
a)
be protected against physical damage;
b)
be guarded in such a manner that access by unauthorized persons can be prevented if there
are energized exposed parts;
c)
be separated from an explosives storage area as follows:
i)
when the transformer is over 5 kV•A, by a distance of at least 15 m of undisturbed
rock or a distance of at least 60 m of open space; or
ii)
when the transformer is 5 kV•A or less, by a distance of at least 15 m of open space; (
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d)
be separated from an explosives storage area in accordance with CAN/BNQ 2910-510 or
separation distances as specified by the regulatory authority having jurisdiction;
e)
be rated for the ambient temperature;
f)
have clearances around it to permit safe access for inspection, maintenance, and repairs;
g)
be mounted on a fireproof foundation and in a location that will minimize the spread of fire;
h)
not be used where flooding is likely to occur; and
i)
be provided with an enclosure that meets the requirements of Rule 2-400 of the Canadian
Electrical Code, Part I.
6.4.3 Underground transformers — Flash point less than 275 °C
A transformer that contains a liquid with a flash point less than 275 °C and is shall not be installed in
an underground mine shall.
(a)
be in an electrical equipment vault;
(b)
have pressure-relief vents that exhaust into the exhaust-air system of the mine; and
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(c)
provide for containing any inadvertent spill or leak.
Note: Many jurisdictions specify regulations for special approval of these transformer installations.
6.4.4 Underground transformers — Flash point greater than 275 °C
A transformer that contains a liquid with a flash point greater than 275 °C and is installed in an
underground mine shall
a)
comply with Clause 6.4.2; and
b)
provide for the safe removal of hazardous gases and products of combustion that can be
produced in the transformer or the room containing the transformer.
Note: Many jurisdictions specify regulations for special approval of these transformer installations.
6.4.5 Underground transformers — Nitrogen Gas filled or dry type
6.4.5.1 Dry type
A nitrogen-filled or dry-type transformer, when installed in an underground mine, shall
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a)
comply with Clause 6.4.2;
b)
have insulating materials equal to or better than Class 150; and
c)
be at least 3 m from the shaft if the transformer is over 5 kV•A.
6.4.5.2 Nitrogen or SF6 Gas filled transformers
Note: Specific health and safety policies and procedures should be developed for responding to potential
hazards associated with gas filled transformers. For example, a procedure requiring the use of breathing
apparatus might be required for entering an equipment room if an SF6 or oxygen monitoring alarm is
activated.
6.4.5.2.1 General
In addition to the requirements of Clause 6.4.5.1, a gas filled transformer, when installed in an
underground mine, shall be
a)
installed in accordance with the manufacturer’s instructions, b) be guarded against open
flames and heat sources;
c)
have a clearly visible warning sign which identifies potential hazards associated with oxygen
displacement. The sign shall be visible from a minimum distance of 2 m; and
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d)
have a minimum of two oxygen monitoring sensors placed at a distance of not more than 1 m
from opposite ends of the transformer. One oxygen monitoring sensor shall be mounted at a
height of not more than 0.3 m from the floor and another at a height of not less than 1.5 m
from the floor and not more than 2 m from the floor. The oxygen monitoring sensors shall
initiate a local audible and visual alarm outside the room or immediate location of the
transformer and signage shall be installed at the alarm location to identify the cause of the
alarm.
Note: Oxygen levels below 19.5% are generally considered dangerous to human health.
6.4.5.2.2 SF6 Gas filled transformers
In addition to the requirements of Clause 6.4.5.1, an SF6 gas filled transformer shall be equipped
with
a)
a minimum of one SF6 monitor; and
b)
a clearly visible sign warning of potentially hazardous by-products caused by arcing within
SF6. The sign shall be visible from a minimum distance of 2 m.
Note: An arc fault in an SF6 environment produces SF6 by-products that can be harmful to human health in
very small quantities.
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6.4.5.2.3 Nitrogen or SF6 Gas filled transformers in a room
For nitrogen or SF6 gas filled transformers installed in a room, the following requirements shall
apply:
a)
The ventilation system shall deliver adequate air exchange to limit the gas accumulation to
levels that are not hazardous to humans during normal operation.
b)
For an SF6 filled transformer, the ventilation system shall draw exhaust air from the bottom
of the side walls and ingress fresh air from the top.
c)
Room access doors shall have clear warning signs identifying the presence of gas filled
equipment and the type of gas.
6.4.6 Capacitors
6.4.6.1 General
A capacitor containing dielectric liquid shall
a)
have a means to contain any spill or leak; and
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b)
be protected in accordance with Rule 26-210 of the Canadian Electrical Code, Part I.
6.4.6.2 Capacitor banks
A capacitor bank containing more than 23 L in one tank or a group of capacitors containing more
than 69 L of dielectric liquid shall have
a)
a fire-resisting barrier with a means to relieve excess pressure away from personnel; (
b)
an automatic fire-suppression system; and
c)
an over-temperature interlock to de-energize the source of supply through a fail-safe means.
Notes:
1)
The fire-resisting barrier is intended to supersede the requirement of Rule 26-012(2)(a) of the
Canadian Electrical Code, Part I, for installation in a service room meeting the requirements of the
National Building Code of Canada where it is not practicable to implement that requirement in an
underground operation.
2)
The over-temperature interlock is intended to protect the capacitor(s) from high ambient temperature.
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6.5 Switchboards and switchgear
6.5.1 General
Switchboards and switchgear shall
a)
be protected against physical damage;
b)
be guarded in such a manner that access by unauthorized persons can be prevented if there
are exposed energized parts;
c)
be separated from an explosives storage area by at least 15 m when a separation distance
measured along mine workings as specified by the regulatory authority having jurisdiction or
be at least 15 m and in accordance with CAN/BNQ 2910-510;
d)
have clearances around them to permit safe access for inspection, maintenance, and repairs;
e)
be installed on a fire-resistant foundation; and
f)
be in a location that will minimize the spread of fire.
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6.5.2 Flash point less than 275 °C
Switchgear containing a liquid with a flash point less than 275 °C shall not be installed in an
underground mine.
Note: A few jurisdictions specify regulations for approval of switchgear installations containing low-flashpoint liquids.
6.5.3 SF6 Gas filled switchgear
In addition to the requirements in Clause 6.5.1, SF6 gas filled switchgear, when installed in an
underground mine, shall comply with the monitoring, warning, and ventilation requirements of
Clause 6.4.5.2.
6.6 Electromagnets
6.6.1 Flash point less than 275 °C
Electromagnets containing a liquid with a flash point less than 275 °C shall not be installed in an
underground mine.
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Note: A few jurisdictions specify regulations for approval of electromagnet installations containing low-flashpoint liquids.
6.6.2 Flash point greater than 275 °C
An electromagnet containing a liquid with a flash point greater than 275 °C shall have
a)
pressure-relief vents to relieve exhaust gases and fluid;
b)
an adequate means of spill containment and collection; and
c)
an over-temperature interlock to de-energize the source of supply through a fail-safe means.
6.7 Installation of storage batteries
6.7.1 Location
Stationary-type storage batteries whose aggregate capacity is 5 kW or more at the 8 h discharge rate
shall be located in storage battery rooms or in areas with equivalent enclosures.
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6.7.2 Installation
Storage battery and battery-charging areas shall meet the following requirements:
a)
storage battery and battery-charging areas shall be located so as to prevent damage by mobile
equipment;
b)
storage battery and battery-charging areas or other enclosures shall be provided with
ventilation sufficient to prevent the accumulation of an explosive mixture of battery gases
shall be ventilated by an adequate amount of fresh air to ensure the diffusion of hazardous
gases that are produced;
Note: The Appendix B note to Rule 26-546 of the Canadian Electrical Code, Part I provides an
example and guidance for removal of hazardous gases from storage battery areas.
c)
battery-charging stations shall be equipped with apparatus suitable for fighting Class C fires;
d)
there shall be no open flames, except as permitted by Item h);
e)
smoking shall be prohibited;
f)
heating, if required, shall not be directed towards station batteries and shall not cause the
ambient temperature of the area to exceed the normal operating temperature range of the
station batteries;
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g)
electrical apparatus shall be enclosed in an approved enclosure or otherwise located to ensure
that no possibility for ignition exists and, where a station battery installation results in a
hazardous location classification, the installation shall follow the requirements of Section 18
of the Canadian Electrical Code, Part I; and
h)
battery repairs may be undertaken after all due precautions to ensure the dissipation of
flammable gases have been taken. Battery charging shall be discontinued while repairs are
being effected.
6.7.3 Disposal
Storage batteries that are permanently removed from service shall be removed from the
underground mine.
The electrolyte of storage batteries shall be removed and neutralized before the batteries are
scrapped or stored for salvage.
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6.8 Grounding
6.8.1 Grounding circuit
The grounding circuit from surface to underground shall consist of at least one external copper
conductor interconnected and bonded with the underground substations, unless equally effective
means of grounding are provided.
6.8.2 Inspection
Where the grounding circuits consists of a conductor external to a cable core, the integrity of the
grounding network shall be verified for continuity and assessed for adequate capacity at intervals
not greater than one year.
6.8.3 Ground potential rise (GPR)
The GPR and transfer of potential at moveable or mobile equipment shall not exceed 100 V.
Note: Refer to Annex A for an explanation of GPR.
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6.9 Communication systems
Note: This Clause deals with communication systems in general within a mine. In addition to the
requirements of these clauses users should consider the reliability of communication systems through mine
emergencies to ensure an effective means of communication with surface is always maintained.
6.9.1 Voice communication
6.9.1.1
Voice communication system voltage shall be 100 V or less, with the exception of the integral ringing
circuit of a telephone.
6.9.1.2
Each circuit of a communication system that extends to the surface from underground shall be
provided with suitable surge-arresting equipment that is properly grounded at the place where the
circuit leaves the underground workings.
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6.9.1.3
Adequate precautions shall be taken to prevent electrical signal or telephone conductors, whether
insulated or not, from being energized by other electrical conductors.
6.9.2 Cage call system
Where a call system is installed for a cage, the system shall be operated at a voltage of 150 V or less.
6.9.3 Shaft signal system
6.9.3.1
Each underground mine shall have a signalling system by which signals can be exchanged between
the tender of a shaft conveyance and the hoist operator for the purpose of controlling the hoist.
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6.9.3.2
The system specified in Clause 6.9.3.1 shall meet the following requirements:
a)
the system shall be operated at a voltage of 150 V or less;
b)
the system shall be supplied with power from a transformer that supplies no other load;
c)
where the primary voltage of the transformer exceeds 750 V,
i)
one conductor of the power supply shall be grounded; or
ii)
the conductors shall be ungrounded if a shielded isolating transformer with a 1:1 ratio
supplies the power for the signal and the circuit has a device to indicate a ground
fault;
d)
the non-current-carrying metal parts of the signalling unit shall be grounded unless the unit
is mounted at least 2.4 m above the floor;
e)
except as specified in Clause 6.9.3.3, the system shall be capable of providing signals for each
shaft compartment that
i)
are audible and clear; and
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ii)
f)
have a distinctive sound for each compartment;
the system shall be arranged so that the hoist operator can return a signal to the worker
signalling; and
g)
the system shall be installed at every working level, landing deck, and any other necessary
shaft location.
6.9.3.3
The system shall be capable of providing a signal that is both audible and visible when installed on a
multi-deck sinking stage.
6.10 Mine hoists
6.10.1 General
Clauses 6.10.2 to 6.10.16 shall apply to all electric hoists, regardless of hoist operation or use.
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6.10.2 Proving tests
Each mine hoist shall be commissioned by a person competent in hoist design or operation.
6.10.3 Protective circuits
6.10.3.1
Each hoist brake shall
a)
have a means for indicating when hoist brake adjustment is required; and
b)
prevent the hoist from moving if braking has occurred outside of the design specification.
6.10.3.2
Each hoist shall have a protective circuit that, when activated, removes power from the hoist motor
or motors and initiates automatic application of the brakes to bring the hoist and any load safely to
rest.
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6.10.3.3
The protective circuit specified in Clause 6.10.3.2 shall
a)
be designed, installed, and maintained in a manner intended to minimize the effect of any
device failure; and
b)
not be altered or adjusted except by authorized persons.
6.10.3.4
Each hoist shall have a manually operable switch that, when activated, initiates the protective circuit
specified in Clause 6.10.3.2. This switch shall be
a)
located within easy reach of the hoist operator;
b)
readily recognizable;
c)
readily operable; and
d)
control reliable as defined in Clause 8.2.5 of CSA Z432.
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(d)
unaffected by computer logic decisions.
6.10.3.5
For each hoist, the protective circuit specified in Clause 6.10.3.2 shall be activated by
a)
any obstruction at an intermediate-loading horizon that prevents free passage of the shaft
conveyance;
b)
undervoltage;
c)
delayed overcurrent in the power circuit; and
d)
instantaneous overcurrent in the power circuit.
6.10.3.6
For each hoist drum, the protective circuit specified in Clause 6.10.3.2 shall be activated by
a)
overwind and underwind within the limits of regular travel;
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b)
overwind and underwind within the intermediate limits of travel;
c)
overspeed outside of the retardation zones;
d)
overspeed inside of the retardation zones;
e)
the upper limit of travel; and
f)
on slope hoists, the upper and lower limit of travel.
Devices used for detection of the upper and lower limits of travel shall be directly operated by the
conveyance.
6.10.3.7
If the hoist has an overwind bypass switch, it shall
a)
be manually operable only;
b)
restrict operation to slow speed when in use; and
c)
allow hoist travel only beyond the first overwind device.
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6.10.3.8
If the hoist has an underwind bypass switch, it shall
a)
be manually operable only; and
b)
restrict operation to slow speed when in use.
6.10.3.9
Devices required to provide the protection specified in Clause 6.10.3.6 shall meet the following
requirements:
a)
if they are mechanically driven by the drum, they shall be protected against loss of motion;
and
b)
if they are solid state, they shall be designed by a competent manufacturer or an engineer, of
a fail-safe design, and provided with a means to detect a loss of protection between the
conveyance and the solid state circuit that detects the position of the conveyance in the
retardation zones (see Annex C).
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6.10.3.10
An indication shall be provided to the hoist operator’s console identifying the position of any
obstruction at an intermediate-loading horizon that prevents free passage of the shaft conveyance.
6.10.4 Backout device
A backout device shall be provided to permit backing out of overwind and underwind positions.
The backout device shall prevent operation of the hoist in the wrong direction and prevent the brake
from being released until sufficient torque has been developed to ensure movement in the correct
direction.
6.10.5 Metering
A device An ammeter that indicates the mechanical load on the hoist motor or motors shall be
plainly visible.
6.10.6 Approach warning signal
In manual operation, the hoist operator shall receive an audible warning of the arrival of the shaft
conveyance at points in the shaft far enough from the top and bottom landing places to permit the
hoist to be stopped safely.
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6.10.7 Depth indicator
Each hoist shall have a depth indicator that
a)
remains functional in the event of an electrical power outage; and
b)
continuously, accurately, and clearly shows to the hoist operator the position
i)
of the shaft conveyance and counterweight, if any;
ii)
in an inclined shaft, of a change in gradient that requires a reduction in hoist speed; (
iii)
at which the overwind, underwind, and track-limit devices are set to operate;
iv)
of any intermediate shaft obstruction;
v)
of the limits of normal travel for the shaft conveyance and counterweight, if any; and
vi)
of any collar doors, dump doors, and crosshead landing chairs.
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6.10.8 Personnel safety device
Where a hoist is used for transporting persons in a skip or skip cage, a device designed and
maintained to minimize the effect of failure shall be installed to
a)
prevent the skip from being hoisted to the dumping position;
b)
automatically signal that persons are permitted to enter the conveyance; and
c)
automatically limit hoist speed to a rate that is safe for the transportation of persons.
6.10.9 Emergency stop alarm
A system shall be installed to notify designated personnel if an emergency stop occurs during
automatic hoisting operations.
6.10.10 High-water-level probe
A probe indicating high-water level that can be read at the hoist console shall be installed below the
working level in any shaft in which natural drainage is not provided or in which flooding can occur
due to equipment failure.
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6.10.11 Operation of level-installed controls
6.10.11.1
Devices installed on levels for the purpose of selecting the conveyance destination and for initiating
hoist motion shall be operable only at the level at which the conveyance is stopped, except where the
system is acceptable for call system operation.
6.10.11.2
Devices installed at levels for initiating hoist motion shall be operable only when the shaft gate is
closed.
6.10.11.3
There shall be a minimum delay of 5 s between the operation of the level-installed control device
used to initiate hoist motion and the actual hoist motion.
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6.10.11.4
The level-installed control device used to initiate hoist motion shall be located so that it can be
operated from inside the conveyance.
6.10.11.5
A level-installed jogging control device shall be located so that it cannot be operated from inside the
conveyance.
6.10.11.6
Where jogging movements are required,
a)
the shaft gate shall be allowed to be open; and
b)
hoist jogging without the delay specified in Clause 6.10.11.3 shall be allowed.
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6.10.12 Operation of cage-installed controls
Devices installed in a conveyance for the purpose of controlling the hoist motion shall be
a)
shall, except for jogging movements, be operable only when the shaft doors and cage doors
are in the closed position; and
b)
shall be capable of initiating an emergency stop.
6.10.13 Friction hoists
6.10.13.1
The requirements of Clauses 6.10.13.2 and 6.10.13.3 are in addition to the other electric hoist
requirements of this Standard.
6.10.13.2
Systems affected by creep or slippage shall be adjusted only when the hoist is at rest and the brakes
are applied. With a solid state hoist control system, this adjustment may be made when the hoist is
in motion.
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6.10.13.3
A friction hoist shall initiate the protective circuit specified in Clause 6.10.3.2, or initiate an
electronically controlled stop, if
a)
rope slippage exceeds established specifications;
b)
there is abnormal movement of the tail-rope loop;
c)
there is abnormal wear of the rope treads or the tread wear limit has been reached; or
d)
the shaft conveyance and the counterweight approach the collar at an excessive speed.
6.10.14 Hoist maintenance operations
Following a trip of the protective circuit specified in Clause 6.10.3.2, hoist operation for maintenance
or testing purposes under the direction of an authorized person may be performed. The hoist shall
be placed back in service only after maintenance or testing is completed.
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6.10.15 Shaft sinking
During shaft sinking,
a)
an underwind limit shall not be required, but the system shall prevent the playing out of
excessive rope;
b)
the protective circuit specified in Clause 6.10.3.2 shall be initiated if the crosshead and the
bucket do not descend together from the bucket-dumping position; and
c)
dual lights shall indicate to the hoist operator that the
i)
the crosshead and the bucket are descending together from the bucket-dumping
position;
ii)
the service doors are in or out of the shaft compartment; and
iii)
the dump doors are in or out of the shaft compartment.
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6.10.16 Hoist maintenance and records
6.10.16.1
The design specifications of a hoist and a record of its commissioning tests shall be kept on file at the
mine.
6.10.16.2
At least once each week, an authorized person shall examine the
a)
hoist motors;
b)
hoist controls;
c)
electrical safety devices; and
d)
signalling devices.
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6.10.16.3
If for any reason the examination specified in Clause 6.10.16.2 has not been performed in the
previous week, the examination shall be performed immediately before a hoist is used.
6.10.16.4
The following shall be documented:
Documentation shall be kept to record
a)
all examinations, servicing, and repairs;
b)
the date and signature of any person performing an examination, service, or repair; and
c)
any failure or accident involving an electrical component of the hoist motor, hoist controls,
electrical safety device, or signalling device.
6.10.16.5
The supervisor shall
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a)
review each entry made in the record file/book specified in Clause 6.10.16.4 within one week
of the creation of the entry;
b)
ascertain that all examinations and all necessary work are done; and
c)
certify in the record book that Clause 6.10.16 has been complied with.
6.11 Transportation
6.11.1 General
Clauses 6.11.2 to 6.11.6 shall apply to electrically powered haulage vehicles, both track and trackless.
6.11.2 Warning equipment
6.11.2.1
Every locomotive, trolley, or motor vehicle shall be equipped with headlights that remain energized
as long as the locomotive or trolley circuit breaker, or the vehicle ignition switch, is in the ON
position. Locomotives equipped with fuses only shall have headlights that are energized upon
contact between the pantograph and trolley wires.
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6.11.2.2
The headlights required by Clause 6.11.2.1 may be controlled by a spring-return dimmer to provide
for signalling and to prevent blinding of oncoming traffic.
6.11.3 Control
The control levers of storage battery and trolley locomotives shall be arranged so that the lever can
be removed only when in the neutral position and cannot be accidentally moved from the neutral
position.
6.11.4 Trolley wires
6.11.4.1
Bare-conductor trolley wires shall be at least
a)
2.4 m above grade if the operating voltage is 300 V or less;
b)
2.7 m above grade if the operating voltage exceeds 300 V but is less than 750 V; or
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c)
4 m above grade if the operating voltage exceeds 750 V.
6.11.4.2
The trolley wire wires in bare-conductor-type trolley systems that use dc power shall be protected
by guards that
a)
are made of insulating material;
b)
extend at least 75 mm below the lowest point of the trolley wire; and
c)
are separated by a distance not less than 225 mm.
6.11.4.3
The trolley lines in bare-conductor-type trolley systems that use ac power shall be guarded to
prevent inadvertent contact.
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6.11.4.4
The supports shall be spaced so that a clearance of not less than 75 mm is maintained between the
trolley wire and the roof of the passageway when the trolley passes under it.
6.11.4.5
The Trolley wires wire used in trolley traction systems shall have a tensile strength not less than that
of No. 1/0 AWG solid hard-drawn copper.
6.11.4.6
The ends of trolley line conductors or feeders shall be dead-ended with strain insulators and with
devices to maintain tension in the trolley lines or feeders.
6.11.4.7
All branch trolley lines shall be provided with
a)
trolley frogs or acceptable jumpers at the points where they leave the main line; and
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b)
insulated trolley sections and switches installed close to the frogs to enable the trolley
branches to be disconnected from the main trolley line.
6.11.4.8
Trolley lines operating at voltages exceeding 300 V shall have
a)
sufficient lighting or reflectors to clearly indicate line locations; and
b)
warning signs posted at points giving access to the lines.
6.11.4.9
Busway-conductor-type (three-phase ac collector type) trolley systems using ac power shall
a)
have ground-fault protection that meets the requirements of Clause 4.5.6;
b)
have ground-conductor monitoring that meets the requirements of Clause 4.5.7; and
c)
meet the requirements of for trolley wire clearance specified in Clause 6.11.4.1.
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6.11.5 Haulage rails
6.11.5.1
Both rails of a rail-return trolley traction system shall be bonded with additional bonding around
switches, frogs, or other openings in the track system and be crossbonded at intervals less than 60 m
apart to ensure a continuous return conductor.
6.11.5.2
All rail bonds of a mine trolley traction system shall be inspected on not less than an annual basis for
damaged bonds or other defects in the rail-return circuit.
6.11.6 Conductors in passages
All conductors, other than trolley wires, in haulage passages or in haulage roads shall be 300 mm
clear of mine cars or locomotives and shall be protected and guarded as necessary.
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6.12 Non-rail bound AC supply to trackless mobile electrical equipment
6.12.1
Clauses 6.12.2 to 6.12.4 shall apply to the source of power, isolation, ground-fault protection,
ground-wire monitoring, portable power cable, multi-phase bus system, slip rings, and take-up reel,
and on-board electrical equipment for trackless non-rail-bound mobile electrical equipment
receiving ac power at voltages exceeding 150 V to ground.
6.12.2
Portable power cables used to supply ac power to mobile electrical equipment shall
a)
meet the requirements of CSA C22.2 No. 96;
b)
meet the requirements of Clause 4.3.2.3 for the rated load current of the mobile electrical
equipment. The voltage drop shall not exceed the design criteria for the system;
c)
meet the system voltage drop design criteria;
d)
have cable entry connectors and conductor terminations that will not be adversely affected by
normal operation of the mobile electrical equipment;
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e)
be suspended or made secure when installed outside the radius of operation of the mobile
equipment;
f)
when spliced, have electrical and mechanical characteristics equivalent to that of the cable;
and
g)
when spliced, be subjected to an insulation voltage test equal to the rating of the cable.
6.12.3
Cable reels installed on mobile electrical equipment shall
a)
be designed to meet the bending ratio requirements of Table 15 of the Canadian Electrical Code,
Part I;
b)
be provided with a limit switch that prevents the removal of all of the electrical cable during
normal operation;
c)
be provided with
i)
a grounding slip ring;
ii)
a ground-check slip ring suitable for control and signal circuits; and
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iii)
d)
power conductor slip rings; and
have access to slip rings posted with a warning indicating the maximum voltage present and
controlled by
i)
a mechanical interlock to ensure that access is available only after the power supply
has been isolated from the supply portable power cable; or
ii)
substantial steel cover plate affixed by a multi-bolt system requiring the use of handheld tools to release. Each cover plate shall carry the warning, “DANGER: ISOLATE
AT SUPPLY SOURCE ALL ENERGY SOURCES BEFORE REMOVING THIS COVER”
and “DANGER : ISOLER TOUTES LES SOURCES D'ÉNERGIE AVANT DE RETIRER
CE COUVERCLE”.
6.12.4
Electrical equipment installed on the mobile electrical equipment shall meet the following
requirements:
a)
all enclosures shall meet the requirements of CAN/CSA C22.2 No. 94.2 for the existing
environmental conditions;
b)
each motor or group of motors shall have separate disconnecting means, overload protection,
and ground-fault protection;
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c)
all motors shall be of the totally enclosed type;
d)
all high-voltage and low-voltage ac wiring and terminations shall be clearly identified,
separated by suitable barriers from automotive circuits and terminals, and have a flame test
rating of FT2 as specified in CSA C22.2 No. 0.3; and
e)
the high-voltage or low-voltage ac supply shall not be used to power or drive any automotive
electrical devices such as lights, battery-charging circuits, gauges, horns, warning devices,
solenoids, and radio control equipment.
7 Underground coal mines
7.1 Application
Clause 7 establishes requirements for underground coal mines. These requirements supplement or
amend the requirements of Clauses 4 and 6.
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7.2 General
7.2.1 Electrical equipment
7.2.1.1 General
Electrical equipment shall comply with Clauses 7.2.1.2 or 7.2.1.3.
Note: See Annex G for more information.
Only approved explosion-protected electrical equipment shall be used in a coal mine. Permission
may be granted by the authority having jurisdiction for the installation and operation of other
electrical equipment in
(a)
the ventilation system intake or a place ventilated by a split of fresh intake air, if interlocks or
other means ensure a positive air flow in the proper direction; or
(b)
an area that is zoned inherently free of gas, as defined by the regulations or the authority
having jurisdiction.
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7.2.1.2 Combustible gas and dust hazards
Where required to be explosion protected for combustible gas and dust hazards, electrical
equipment shall be
a)
b)
approved for Group I applications and shall have an equipment protection level (EPL) of
i)
Ma where a very high level of explosion protection is required; or
ii)
Mb where a high level of explosion protection is required; or
approved with an equivalent level of explosion protection for the degree of explosion risk
involved.
7.2.1.3 Combustible coal dust hazards
Where only combustible coal dust hazards exist, electrical equipment and installations shall comply
with the requirements of Section 18 of the Canadian Electrical Code, Part I for Class II hazardous
locations and shall provide explosion protection methods that are acceptable for the hazardous
location involved.
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7.2.2 Use of electricity
Electricity shall not be used where the methane combustible gas content of the air around the
electrical apparatus or equipment exceeds 1.25%, as determined by an approved methane detector.
Approved portable electric miners’ lamps, signalling or telephone systems, portable methane
detectors, and intrinsically safe systems shall be exempt from this restriction except that equipment
having a degree of protection, EPL “Ma”, or equivalent, shall be permitted to remain energized.
7.2.3 Auxiliary ventilation
If an area is maintained in a safe condition by auxiliary fans, the power source to the area shall be
positively interlocked in such a manner that failure of the auxiliary ventilation system shall interrupt
power to the area, except that the equipment referred to in Clause 7.2.2 may remain energized.
Approved portable electric miners’ lamps, methane detectors, and intrinsically safe systems shall be
exempt from this restriction.
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7.3 Work on energized equipment — Repairs and alterations
Except with special permission With the exception of intrinsically safe systems that can be repaired
while energized, repairs, maintenance, or alterations shall not be carried out on energized
equipment. Such equipment shall be placed in an electrically safe condition prior to the
commencement of work.
The action of relamping luminaires shall be subject to this requirement.
7.3.2 Precautions
If adjustments or repairs are made on energized intrinsically safe equipment in accordance with
Clause 7.3.1, all necessary precautions shall be taken to ensure that the work is done safely.
7.4 Electrical equipment in dusty locations
Where other than approved electrical equipment is permitted to be used in a location that is subject
to an atmosphere containing coal dust, or where coal dust is liable to collect on the equipment, such
apparatus shall be provided with enclosures that are acceptable for use in Class II, Group F
hazardous locations (see CSA C22.2 No. 25). General-purpose enclosures may be installed in dustfree rooms (see Appendix E of the Canadian Electrical Code, Part I).
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7.4 Voltage at coal face
Except by approval of the authority having jurisdiction special permission, mobile electrical
equipment supplied by portable power cable used at the coal face shall not be operated at a voltage
exceeding 3300 V. Where approval is given by the authority having jurisdiction, safe work
procedures shall be developed to cover the preconditions to usage, environmental monitoring, and
use of high-voltage insulation testing.
A voltage exceeding 150 V shall not be used for operating portable hand-held equipment.
7.5 Main fans
Main fans installed on the surface that supply ventilation to the underground workings shall be, as
far as practicable, supplied from an electrical power source separate from that supplying equipment
in the underground workings.
For each mine in which electricity is used, there shall be a plan or diagram showing the direction of
ventilation in underground workings.
7.7 Opening of enclosures of explosion-proof equipment
The enclosures of explosion-proof equipment shall not be opened if energized parts will be exposed
to a surrounding hazardous atmosphere.
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7.6 Distribution system integrity
7.6.1
At least once a year, the high-voltage distribution system shall be visually inspected and tested to
verify integrity through nondestructive testing means, which shall and may include methods such
as dissipation factor (loss angle) and time domain reflectrometry (TDR). The results of the inspection
and testing shall be recorded in the electrical report book kept at the mine and compared with the
discard criteria.
Note: Time domain reflectometry is often referred to as TDR.
7.6.2
The inspection and testing shall be completed by a qualified person or persons. The testing of cable
assemblies shall be completed in accordance with IEEE Std 400.
7.6.3
Discard criteria shall be determined and recorded in the electrical report book for the mine in
consultation with the manufacturer for specific equipment types, including transformers, cable
assemblies, and circuit breakers.
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7.6.4
Safe work procedures shall be developed and used for testing.
7.6.5
The GPR and transfer of potential at mobile equipment shall not exceed 50 V.
7.8.5
Ground network resistance from remote points shall be measured to ensure that the ground
potential rise (GPR) is less than 50 V at the mobile equipment.
7.7 Wiring methods for non-intrinsically-safe wiring
7.9.1 Conductors
Conductors supplying fixed equipment shall be armoured or enclosed in acceptable conduit.
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7.7.1 Cables
7.9.2.1
Portable power cables shall be shielded and comply with the applicable requirements of CSA C22.2
No. 96.
7.7.1.1
Interconnecting power cable on mobile electrical equipment, e.g., cable interconnecting a contactor
enclosure and a disconnect switch or a motor, shall
a)
have each power core shielded;
b)
have the shield grounded; and
c)
be mechanically protected. and
(d)
comply with the applicable requirements of CSA C22.2 No. 96.
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7.9.2.3
Suitable terminating facilities shall be provided to protect cables from harm due to moisture or
mechanical damage.
7.7.2 Portable power Trailing cables
7.7.2.1
Portable power Trailing cables supplying mobile electrical equipment operating at voltages
exceeding 150 V shall be shielded and meet the applicable requirements of CSA C22.2 No. 96 and
each power conductor shall be individually shielded.
7.7.2.2
The minimum size of the power conductors shall be No. 10 AWG.
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7.7.2.3
Portable power Trailing cables shall be attached to machines and to the switchgear that controls the
machines either by direct entry through approved cable glands or by approved plug-and-socket
couplings of a restrained or bolted type.
7.7.2.4
Every trailing portable power cable in use shall be
a)
tested for insulation resistance and continuity by a qualified person at regular intervals
acceptable to the authority having jurisdiction; and
b)
examined externally at the commencement of each shift by the machine operator to ensure
that it is mechanically sound and free from visible damage.
7.7.2.5
When a cable-handling system is employed, it shall be examined inspected prior to the
commencement of each shift. Defects or abnormalities found during the inspection shall be recorded
and the system shall not be used if found to be in unsafe condition.
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7.7.2.6
Portable power Trailing cables that are defective or damaged, or that have caused protective devices
to operate, shall be isolated from the supply.
7.7.2.7
When a cable jacket has been mechanically damaged but there has been no damage to the power,
ground-check, ground conductors, or metallic shield, a temporary repair may be made to the cable
after it has been tested.
7.7.2.8
A cable that has been mechanically damaged shall, as soon as possible, but at most within 12
working hours, be given a permanent repair or replaced.
7.7.2.9
Temporary repairs shall not be made to the power, ground-check, ground conductors, or metallic
shields.
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7.7.2.10
Portable power Trailing cables shall be repaired in such a manner that
a)
the conductivity and mechanical strength of the conductors are not reduced;
b)
the conductors have a dielectric strength equivalent to that at any other section of the cable;
and
c)
equivalent protection is provided as a substitute for the original jacketing.
A final test to verify the integrity of the cable shall be performed and include a visual inspection, an
insulation resistance test, and a ground continuity test.
7.9.3.11
Trailing cables supplying hand-held equipment or equipment operating at voltages exceeding 150 V
shall be provided with ground-fault protection.
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7.7.2.11
Where a continuous ground-monitoring system is used, the number of uninsulated grounding
conductors may be reduced to one, but the total conductance of the uninsulated grounding
conductor(s) shall be more than
a)
60% of the conductance of the largest power conductor; or
b)
50% of the conductance of the largest power conductor, where the prospective ground-fault
current is less than 1 A.
7.7.3 Connectors or couplers
Connectors or couplers used with trailing portable power cables shall be provided with a means to
ensure that the grounding circuit is the first-to-make and the last-to-break.
7.7.4 Feeder and branch circuits
Terminals of main, feeder, or branch circuits shall not be located nearer to the working face than the
last ventilating crosscut.
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7.7.5 AC supply to mobile electrical equipment
Mobile electrical equipment operating at voltages exceeding 150 V shall be supplied by a system in
which
a)
the neutral system is grounded through a neutral-grounding device that limits ground-fault
voltage at the mobile equipment to 50 V or less;
Note: This does not refer to transferred voltage from a utility fault (see Annex A).
b)
ground-fault protection is provided;
c)
continuous ground-conductor monitoring is employed; and
d)
de-energized conductors are continuously monitored and do not permit re-energization if a
ground-fault exists.
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7.8 Installation of equipment
7.8.1 General
7.8.1.1
Adequate ventilation shall be provided to prevent the development of an ambient air temperature
exceeding the rated ambient temperature for the electrical equipment.
7.8.1.2
Disconnecting means shall be installed on all circuits and shall be as near as practicable to the point
of supply.
7.8.1.3
On circuits operating at voltages exceeding 300 V, the disconnecting means shall be of the visiblebreak type unless the requirement for explosion-proof housing (see Clause 7.2.1) makes this
impracticable.
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7.8.1.4
Due to possible safety-related incompatibilities, equipment that conforms to this Standard but is
approved by different authorities shall not be intermixed except by permission of the authority
having jurisdiction.
7.8.2 Transformers
7.8.2.1
Transformers shall
a)
be protected from mechanical damage by location or guarding;
b)
be protected from falling or splashing moisture;
c)
not be located within 60 m of stored explosives; and
d)
have an air space between the transformer casing and adjacent surfaces, except floors, of not
less than
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i)
300 mm if the adjacent surface is of combustible material;
ii)
6 mm if the adjacent surface is of
1)
noncombustible material;
2)
combustible material adequately protected by noncombustible heat-insulating
material other than metal; or
3)
combustible material shielded by grounded sheet metal with an air space of not
less than 50 mm between the sheet metal and the combustible material; or
iii)
the manufacturer’s recommended clearances from the adjacent surfaces, if they exceed
the minimum clearances specified in Items i) and ii).
7.8.2.2
Permanent transformers shall be provided with
a)
adequate through-ventilation for the purpose of equipment cooling; and
b)
fire-extinguishing devices in close proximity on the intake-air side.
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7.8.3 Switchboards and switchgear
Switchboards and switchgear shall
a)
be installed in accordance with Clause 6.5.1; and
b)
not be located closer than 3.5 m to any shaft or winze timber, if operated at voltages
exceeding 300 V.
7.8.4 Storage battery rooms or other enclosures and battery-charging
areas
7.8.4.1
Storage batteries that are stationary when in use shall be located in storage battery rooms or
equivalent enclosures if the aggregate capacity at the 8 h discharge rate exceeds 5 kW and the
batteries are in unsealed jars or tanks.
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7.8.4.2
Storage battery rooms or other enclosures and battery-charging areas shall be provided with
ventilation sufficient to prevent the accumulation of an explosive mixture of battery gases.
7.8.4.3
Storage battery rooms or other enclosures and battery-charging areas shall be ventilated by an
intake-air split sufficient to ensure the diffusion of gases discharged into the return airway.
7.8.4.4
The location for battery-charging stations shall be
a)
designated as such and shall be used for no other purpose;
b)
shown on a mine plan that is available to the authority having jurisdiction and indicates the
direction of the airflow; and
c)
in an area that has stable strata.
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7.8.4.5
The construction of battery-charging stations shall be rendered fireproof.
7.8.4.6
An air vent shall be installed at the highest part of the storage battery room or other enclosure to
allow any gases generated to escape into the atmosphere.
7.8.4.7
All stations shall be equipped with an adequate automatic fire-suppression system. Upon operation
of the fire-suppression system, an alarm shall alert persons responsible for knowing the status of the
system.
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7.8.4.8
Heating, if required, shall be of the forced-air type, with the heating element located outside the
charging station and arranged so that fresh air shall flow over the heating element when the element
is operating.
7.8.4.9
Material other than standby batteries and material required for routine battery maintenance shall
not be stored in the battery-charging station.
7.8.4.10
Electrical equipment shall either be approved or located so as to ensure that no possibility for the
ignition of hydrogen exists.
7.8.4.11
Battery-charging equipment shall be located at or near floor level and permanently connected to the
main power supply. The source of supply shall be interlocked to de-energize at 1% concentration of
hydrogen gas.
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7.8.4.12
Battery-charging cables shall be contained within a protective jacket having an FT5 rating as
specified when tested in accordance with CSA C22.2 No. 0.3 2556.
7.8.4.13
Battery repairs shall be performed only after precautions have been taken to ensure the dissipation
of flammable gases. Battery charging shall be discontinued during repairs.
7.8.5 Conveyor systems
7.8.5.1
Conveyors that start automatically shall have warning signs posted at each access point indicating
that the conveyor is subject to automatic start. The conveyor-control system shall incorporate a
prestart warning circuit that sounds an audible alarm throughout the length of the conveyor(s).
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7.8.5.2
Armoured-face conveyors shall be exempt from the requirements of Clauses 4.4.3.1 and 4.4.3.2
provided that stop switches are installed along the conveyor at intervals not exceeding 10 m and a
prestart warning is incorporated into the control system.
7.9 Protection and control
7.9.1 General
7.9.1.1
Protective control devices shall be equipped with test facilities so that the operation of the groundfault and ground-monitoring circuitry can be checked at regular intervals.
7.9.1.2
The protection and control cables of different circuits or systems, when installed in the same
conduit, shall be individually shielded, and the circuits shall be designed to be fail-safe.
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7.9.2 Protection
Electrical equipment shall be provided with
a)
manually operable devices that disconnect all ungrounded conductors at the point of supply;
and
b)
devices that automatically open the circuit and will not automatically reset if overcurrent,
overload, undervoltage, or a ground fault occurs on any of the power conductors.
7.9.3 Control
The covers of explosion-proof equipment shall be mechanically or electrically interlocked to prevent
access to energized parts. Such interlocking shall not be required on enclosures that are suitably
marked: “DANGER: ISOLATE ALL ENERGY SOURCES BEFORE REMOVING THIS COVER” and
“DANGER: ISOLER TOUTES LES SOURCES D'ÉNERGIE AVANT DE RETIRER CE COUVERCLE”,
or the equivalent (e.g., ”ISOLATE ELSEWHERE BEFORE OPENING”).
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7.10 Grounding
7.10.1 General
7.10.1.1
The metallic covering of a cable shall not be used as the sole grounding conductor.
7.10.1.2
Electric motors, component parts, or chambers associated with the assembly of machines or
equipment shall be grounded with copper conductors to the power supply ground system. The
conductance of the ground conductor shall be more than 50% of the conductance of the largest
power conductor and have a minimum size of No. 10 AWG.
7.10.2 DC systems
7.10.2.1
Clauses 7.10.2.2 and 7.10.2.3 shall apply to dc systems other than
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a)
trolley systems; and
b)
equipment using dc motors and generators in the Ward-Leonard connection or similar types
of control.
7.10.2.2
Two-wire dc systems operating at voltages of 250 V or less, but exceeding 50 V, shall be grounded
and equipped with ground-fault monitoring equipment.
7.10.2.3
Two-wire dc systems operating at voltages exceeding 250 V shall be
a)
provided with a neutral point so that the maximum voltage between the neutral point and
other points on the system is 250 V or less; or
b)
equipped with ground-fault monitoring equipment.
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7.10.3 Grounding of ac systems
Systems operating at voltages-to-ground exceeding 150 V shall be
a)
grounded through a neutral resistance impedance; and
b)
provided with ground-fault protection.
Note: See Annex H for additional information.
7.11 Intrinsically safe systems — Signal systems
Note: See Appendix F of the Canadian Electrical Code, Part I.
7.11.1
Acceptable electric or electronic signal systems may be installed in mines having an entrance by
shaft or slope, and may replace mechanical signal systems, provided that voice communication has
been installed at regular stations. Signal systems installed in the shaft or slope shall be powered by
an uninterruptible source.
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7.11.2
Signal system equipment shall not be mounted on shaft timbers, with the exception of mine hoisting
signal switches.
7.11.3
Apparatus used for signal purposes in an underground mine shall be protected against moisture
and mechanical damage.
7.11.4
Cables to be used only for intrinsically safe circuits shall have an FT1 flame test rating as specified in
CSA C22.2 No. 0.3, using the criteria of CSA C22.2 No. 96.
7.11.5
Where practicable, conductors and cables shall be installed on the side of roadways or haulage roads
opposite to that on which power conductors, apparatus, or cables are installed, so as to minimize
induction from, and prevent contact with, the power conductors.
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7.12 Mine lighting
7.12.1 General
The lighting system shall be installed, commissioned, and maintained in accordance with the
manufacturer’s instructions designed to prevent the creation of circumstances that can lead to
electrical shock, fire, or ignition of methane or coal dust.
7.12.2 Operating voltage
Lighting systems shall not be operated at voltages-to-ground exceeding 150 V without the approval
of the authority having jurisdiction. This restriction shall not apply to the primary voltage levels of
transformers used to provide lighting power.
7.12.3 Protection
Lighting circuits shall be limited to 20 A per circuit and have overload protection at less than 125%
of normal circuit current.
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7.12.4 High-intensity-discharge lighting
In locations where high-intensity-discharge (HID) lighting is provided and supplemented with
emergency lights, the lighting system shall contain a sufficient mix of instant-start lamps to ensure
an adequate level of illumination during the changeover from emergency to normal power circuits.
7.12.5 HID High-intensity-discharge lamps containing elements of
sodium
HID lamps containing elements of sodium shall not be allowed underground.
7.13 Shotfiring
7.13.1 General
7.13.1.1
Energy derived from the mine power system shall not be used for shotfiring.
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7.13.1.2
In the vicinity of the shotfiring zone, all mine power cables and conductors of other systems shall be
isolated from their source of energy and protected prior to and during the shotfiring operations.
7.13.1.3
After shotfiring, power shall not be restored to the cables or systems specified in Clause 7.15 13.1.2
until they have been examined and found free of physical damage.
7.13.2 Shotfiring apparatus
7.13.2.1
Only approved shotfiring apparatus, compatible electric detonators, and test instruments shall be
used for shotfiring operations.
7.13.2.2
Shotfiring apparatus shall be stored at the mine surface in a cool, dry place when not in use.
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7.13.2.3
Shotfiring apparatus shall be examined, cleaned, and tested with approved test equipment in
accordance with the manufacturer’s instructions at least once every three months.
7.13.2.4
Prior to initial issue or reissue, shotfiring apparatus shall be tested with approved test equipment.
7.13.2.5
Capacitive-discharge-type shotfiring apparatus shall be tested to ensure that any residual charge
decays within the time limit specified by the manufacturer.
7.13.2.6
Maintenance and testing of shotfiring apparatus shall be performed only by qualified persons. The
dates of maintenance and each test carried out shall be entered in a book provided for that purpose.
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7.13.2.7
Defective shot firing equipment shall be tagged as defective and removed from the mine.
7.15.2.7
Defective shotfiring apparatus shall not be used.
7.13.2.8
Shotfiring apparatus shall not be opened underground.
7.13.2.9
Shotfiring apparatus shall be used only for the purpose for which it was designed, in accordance
with the manufacturer’s instructions.
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7.13.3 Shotfiring cable
Shotfiring cable shall meet the following requirements:
a)
the construction shall be two-conductor stranded copper, with each conductor separately
insulated, and served overall with a weatherproof sheath to form a flexible cable;
b)
the size of the conductors shall exceed No. 16 AWG and the conductors shall have a loop
resistance of 2 Ω or less;
c)
the conductors shall extend continuously from the firing station to the shotfiring zone; and
d)
the shotfiring cable shall be clearly identified as such by colour or marking.
7.13.4 Installation and use
7.13.4.1
Shotfiring cables shall not be installed within 150 mm of energized power, lighting, signalling, or
communications conductors.
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7.13.4.2
Shotfiring cable leading to a shotfiring zone shall have the conductors short-circuited at the
shotfiring-apparatus end while detonator leads are being connected and whenever the cable is not in
use.
7.13.4.3
The shotfiring cable shall not be connected to the shotfiring apparatus until the shot or round of
shots is ready for detonating (firing). It shall be disconnected immediately after the firing action is
completed.
7.13.4.4
The following requirements shall apply when more than one shot is connected to be fired in a single
round:
a)
the electric circuit shall be tested with an approved test instrument before the circuit is
connected to the shotfiring apparatus; and
b)
an approved multi-shot shotfiring apparatus shall be used to fire the round.
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7.13.4.5
The shotfiring cable shall be maintained in serviceable condition, used only for shotfiring, and
stored in a safe dry place when not in use.
Table 1A
Allowable ampacities for portable power cables (amperes per conductor)
(See Clause 4.3.2.3.)
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Table 1A (Concluded)
Notes:
1)
The ampacity values are based on a single isolated cable in air at an ambient temperature of 30 °C. For
cables operating at a different ambient air temperature, the ampacity shall be obtained by multiplying
the appropriate value from this Table by the correction factor for that other ambient temperature as
specified in Table 1B.
2)
The ampacities are based on a conductor temperature of 90 °C. For conductor temperatures other than
90 °C, the ampacity of a given conductor type shall be obtained by multiplying the appropriate value
from this Table by the correction factor for that conductor temperature as specified in Table 1C.
3)
When cables are used with one or more layers wound on a drum, the actual internal temperature of the
cable can exceed the 90 °C rating. Thermal overheating can shorten the run life of the cable. The
appropriate ampacity correction factors are specified in Table 1D.
4)
For single-conductor cables with metallic shields, the ampacity values are for cables operated with an
open-circuit shield.
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Table 1B
Temperature correction factors
(See Clause 4.3.2.3 and Table 1A.)
Table 1C
Conductor rating correction factors
(See Clause 4.3.2.3 and Table 1A.)
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Table 1D
Layering correction factors
(See Clause 4.3.2.3 and Table 1A.)
Table 2
Minimum clearances for movement of equipment under supervision of
qualified personnel
(See Clauses 4.3.6.3 and 4.3.6.5.)
* These are phase-to-ground voltages for grounded systems and phase-to-phase voltages for ungrounded
systems.
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Table 3
Minimum clearances for movement of equipment under supervision of
unqualified personnel
(See Clause 4.3.6.5.)
* These are phase-to-ground voltages for grounded systems and phase-to-phase voltages for ungrounded
systems.
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Annex A (informative)
Ground potential rise and ground-fault voltage
Note: This Annex is not a mandatory part of this Standard.
A.1
IEEE Std 80 specifies requirements for ground potential rise (GPR). GPR Ground potential rise can
be transferred to remote equipment by a ground conductor. This transferred voltage should not be
confused with ground-fault voltage, which is a voltage drop in the ground conductor when a
ground fault occurs. Figure A.1 helps to illustrate ground potential rise GPR and ground-fault
voltage. Disconnecting means and protection are not shown.
In resistance-grounded systems, it is standard practice to assume zero-impedance fault paths and
consider only the neutral-grounding resistors to calculate prospective ground-fault currents. The
prospective ground-fault current is used to calculate worst-case values of ground potential rise GPR
(see Clauses 5.3.3.3, 6.8.3, and 7.6.5) and ground-fault voltage (see Clause 4.5.6) as follows:
a)
The prospective ground-fault current, IA, is equal to the line-to-neutral voltage at the
secondary of the fixed substation transformer divided by the resistance of the neutralgrounding resistor (R1).
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b)
The ground potential rise GPR at the movable substation is equal to the product of IA and the
resistance of the station ground (RS2) (see Clauses 4.4.1.1 and 5.3.3.3). This ground-potential
rise will be transferred to the frame of the trailing portable power cable-fed equipment (see
Clauses 5.3.3.3, 6.8.3, and 7.6.5).
c)
The prospective ground-fault current, IB, is equal to the line-to-neutral voltage at the
secondary of the movable substation transformer divided by the resistance of the neutralgrounding resistor (R2).
d)
The ground-fault voltage at the frame of the trailing portable power cable-fed equipment is
equal to the product of IB and the resistance of the ground wire (RGW) (see Clauses 4.4.1.1,
4.4.1.2, 4.4.1.4, 4.4.1.5, and 7.7.5).
The person touching the frame of the trailing portable power cable-fed equipment will be exposed to
a transferred ground-potential rise when Fault A occurs and to a ground-fault voltage when Fault B
occurs.
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Figure A.1
GPR Ground potential rise and ground-fault voltage
(See Clause A.1.)
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Annex B (informative)
Overhead supply line clearances
Note: This Annex is not a mandatory part of this Standard.
B.1
Material storage in yards, and machines used to load or unload material, create hazards for
personnel and machines in the vicinity of bare overhead supply lines. To maintain safe clearances
and reduce the risk of accidental contact, the following should be considered in yard location,
layout, material storage, and operation of machinery:
a)
Where possible, and considering the machinery used to load or unload materials, storage
yards and product stockpiles should be located a safe distance from supply line rights-ofway.
b)
Procedures for maintaining safe clearances should allow for the types of machinery (boom
trucks, cranes, large forklifts, excavators, etc.) used to load and unload material.
c)
Operations such as road dressing, grading, and snow clearing can require protecting poles
and guy wires to prevent physical damage.
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d)
Employees should be trained in procedures for maintaining safe clearances.
B.2
Accidental contact with overhead supply lines by rear-dump haul trucks travelling with box up is a
significant operational hazard in mines. When applying Clause 4.3.6.3 to overhead supply lines
crossing haul roads, the ”combined vehicle and load height” should be considered to mean the full
box-up height of the haul truck.
B.3
Where overhead supply lines cross haul roads, the following markings and notifications should be
provided:
a)
A minimum of two per span visible markers should be attached to the overhead supply lines
to allow for easy identification of the overhead lines.
b)
Visible reflective warning signs indicating the presence of the overhead supply lines should
be posted at a distance of no less than 50 m of each side of the crossing, and within 50 m of
the intersection of any haul road running along the side or parallel with the overhead supply
line that allows turning towards the overhead supply line crossing (see Figure B.1).
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c)
The warning signs should identify the highest voltage class as well as the minimum overhead
supply line height clearance with respect to the bare road.
d)
When projected snow accumulations on the haul road will adversely affect the posted line
height clearance [see Item c)] at the line crossing, mine operations should issue a notification,
twice per shift, to all heavy equipment operators of the projected amount of reduction in
clearance or the projected minimum height clearance level, until the snow accumulation is
removed.
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Figure B.1
Warning signs for overhead supply line haul roads crossing over haul
roads
(See Clause B.3.)
(New)
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Annex C (informative)
Mine hoists
Note: This Annex is not a mandatory part of this Standard.
C.1 Fail-safe
C.1.1 Circuit design
The safety circuit for a hoist is a protective circuit designed to stop the hoist if certain operating
limits or conditions are exceeded. The importance of this circuit means that it should be available to
work at all times or, if a malfunction in the circuit occurs, that it should fail in a manner that does
not endanger people in the conveyance or damage the hoist itself. In the past, the intent of fail-safe
was met by using relays and solenoids that, if they became de-energized, caused the brakes to come
on and/or power to be removed from the hoist motor.
Hoist safety circuits using solid state devices as part of the safety circuit should be designed so that a
failure in a solid state device will not affect the ability of the safety circuit to bring the hoist to a safe
stop.
A solid state device can fail in either a “shorted” or “open” condition, or it can go into a “locked-up”
condition in which the device becomes frozen in its current state. If allowance is not made for these
failure modes, the hoist’s safety circuit can be rendered inoperative.
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Note: A mine hoist safety (protective) circuit implies a series of protective devices and measures, any one of
which will immediately initiate stopping of the hoist and remove power, if activated. A protective circuit refers
to devices that are integrated into the hoist control to provide warnings, slow-downs, stops or power removal,
if activated.
C.1.2 Guidelines
C.1.2.1
The concept of fail-safe applies to the entire system, not to individual components. This requires the
concepts of device monitoring and redundancy. These terms are different: device monitoring
requires a separate circuit to check that a safety device has operated properly, while redundancy
requires parallel devices with their outputs in series to the next stage of the circuit. An example of
device monitoring is having the part of the circuit that calculates conveyance position from drum
turns also monitor magnet switches as magnets mounted on the conveyance pass by.
For devices to be truly redundant, there needs to be enough separation, both physically and in
function, so that one failure will not affect both devices. Two separate input cards, if fed from the
same power source, are not redundant.
In general, the philosophy is to have a minimum of two programmable logic controllers (PLCs) or
computers, per hoist, replace the when replacing a mechanical safety controller. One of these PLCs
or computers can be the hoist controller as well.
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C.1.2.2
In most cases, the software program that controls the operation of the solid state devices can be
changed without any need to rewire components. In light of this, there should be a
“revision/modification” program in place. Access to the program should be restricted to ensure that
changes to the program are made by people who know the system and the ramifications of their
changes. The manufacturer or a competent computer programmer should be consulted about
changes to the program. Restricted access may be by physical means such as keyed switches or by
electronic means such as passwords. These means may be combined to allow for various levels of
access to permit maintenance, troubleshooting, and minor changes to operating conditions.
Part of regularly scheduled maintenance at the mine should include an annual comparison of the
installed program and parameters with the master copy established during hoist commissioning.
Differences between the two, most probably in operating parameters, should be documented with
respect to why there is a difference, who made the change, and who authorized it. A hazard analysis
of the changes should be made. A study by the Health and Safety Executive in the United Kingdom
showed that changes to programs caused the biggest problem with computerized controls.
C.1.2.3
The construction of a solid state device should be compatible with the environment in which it
operates. The designer, upon receiving information on the environment, should include features in
the design that control the environment so that it is acceptable for the equipment or that allow the
equipment to handle all aspects of the environment. This includes not only the physical aspects of
the environment, such as temperature, moisture, and dust, but also the aspect of electro-magnetic
interference coupling into the conductors within the solid state device.
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C.1.2.4
The power supply for a solid state device should be reliable, “clean”, and capable of handling
“dirty” signals.
Reliability can include independent power sources to the cards, as well as the use of battery backup
functions required to maintain memory of operating conditions in case of power failures.
Conveyance position in the shaft is one example of an operating condition that needs to be
maintained for a period long enough to rescue passengers.
“Clean” refers to distortions in voltage and current waveforms. Voltage fluctuations can be caused
by the starting of large motors fed from the same source, while spikes can be created by the use of
switching power supplies.
C.1.2.5
Manual override should be available no matter how well the solid state devices have been designed.
This may be considered to be the emergency stop button available to the hoist operator, with
contacts hardwired in series with the outputs of the solid state section of the safety circuit. The
circuit needs to be independent of everything else. Care should be taken that this manual override
feature cannot be bypassed by the programmable parts of the solid state circuit.
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C.1.2.6
All newly designed safety controllers should demonstrate a proven track record before they are used
without a proven safety controller as a backup.
C.1.2.7
The electronic device being used to control the hoist should be separate from the safety device in
order to prevent a single failure from defeating both functions. This also reduces the risk of
inadvertent errors and software errors.
C.1.2.8
The sensing of speed and position is very important. Each conveyance should be monitored, and the
outputs should be compared, to ensure that dangerous differences result in appropriate warnings
and, if necessary, a hoist stoppage.
General practice is to have pulse encoders monitor conveyance position. For friction hoists, normal
practice is to have pulse encoders for each PLC or computer. The pulse encoders should not be
driven by the same input shaft and may be driven by the hoist drum, the deflection sheave (if any),
or the hoist motor.
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For a skip or cage hoist that is not being used for single-line hoisting, one encoder on each drum is
likely to be sufficient.
For a cage hoist that is used for single-line hoisting, two encoders are needed, and these encoders
should be totally independent (i.e., one on the drum and one on the motor) so that failure of either
encoder will leave the other encoder functioning.
C.1.2.9
Independent monitoring of the position of the conveyances should be done at the end zones.
Physical switches located in the shaft should be used as much as possible, and certainly at the end
zones at the top of the shaft. For a single-drum hoist, or a double-drum hoist used to convey persons
in a single-drum mode, a device such as an ultrasonic, magnetic, or microwave device, or a shaft
switch, should be located at the bottom end zone.
This monitoring is independent of the safety device, and the difference between the two devices
should be constantly monitored so that suitable alarms and stoppages result.
Encoders have failed due to power supply problems, grease blocking the slots, and exhaustive hoist
movements. For this reason these reasons, independent monitoring should be provided.
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C.1.2.10
Resetting of the safety device based on the exact position of the conveyances should be a
requirement. Resetting can be done at fixed places in the shaft, such as loading pockets or the final
stop. Some solid state safety devices resynchronize on the fly.
C.1.2.11
Bypassing of some of the devices to allow for controlled travelling for repair or for rope changing
should be built into the system. Software overrides should not be allowed.
C.1.2.12
A “watchdog timer” or equivalent device should be an inherent part of the design of each PLC or
computer. The timer checks that pulses are still being implemented to prevent the system from
looping endlessly or becoming idle because of programming errors.
C.1.2.13
The scan time of the PLC should be less than 120 ms milliseconds. Otherwise, there can be an
unsatisfactory delay when an event such as a track-limit trip occurs.
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C.2 Automatic hoisting
When a cage or skip/cage is in automatic mode and a trip occurs while the hoist is conveying
persons, a hoist operator should be available within 10 min to determine the cause of the trip and, if
need be, to operate the hoist in manual mode. For automatic hoisting the following should apply:
a)
There should be an emergency stop switch at each level where there is access to the
conveyance. The switch should be red, push to apply, and operative only when the hoist is in
automatic mode.
b)
The design of a semi-automatic cage hoist should incorporate an emergency call feature from
each active level. This is to allow the cage to come to a specific level and bypass other levels
that might be programmed in the system.
c)
There should be a written procedure to transfer the hoist from manual to automatic and from
automatic to manual.
d)
A written procedure should be established for the control mode at each level. The procedure
may include such items as hoist destination, jog up, jog down, change decks, and emergency
call.
e)
Any worker who operates the controls should be authorized and trained to do so.
f)
When the cage hoist is in automatic, a warning should sound (for approximately 5 s) once the
cage and shaft doors are closed and the hoist has been programmed to leave for another level.
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g)
For a cage hoist, there should be two green lights, visible from the cage and the level, that
indicate when it is safe to enter or leave the cage.
h)
If there is no hoist console at the location where the hoist and associated machinery are
located, and if the hoist is used to transport workers, there should be at least two parallel
control circuits from the remote console to the hoist.
i)
For an ac hoist motor, normal practice is to have an upstream circuit breaker trip upon
initiation of a safety circuit. For a dc hoist motor, normal practice is to have a loop breaker
between the drive and the motor designed to trip on the initiation of a safety circuit. These
practices should be followed.
j)
The following should apply when the hoist operator is remote from the hoist:
i)
thermal protection should be provided for all main bearings, brake paths, motor
windings, and motor-generator sets;
ii)
moisture on the brake pads should be detected;
iii)
brake paths and linings should be protected against contaminants;
iv)
fire detection should be provided in the hoist room; and
v)
provision should be made to convey hoist room sounds back to the remote hoist
console. A switch should be available so that the hoist operator can listen to these
sounds at his or her discretion.
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k)
When more than one hoist is controlled from the same location, and when more than one
hoist is in automatic mode, there should be no external distractions for the operator if one
hoist needs to be operated in the manual mode.
C.3 Mechanical recommendations
One or more brakes should be provided to automatically apply an emergency stop to each operating
drum. Any hoist used to transport workers should have a braking system that consists of at least
two brakes. A double-drum hoist with one brake per drum will normally satisfy this
recommendation. If operated in single mode, a double-drum hoist should have a second brake
(usually a pinion brake). For new hoist installations, at least two brakes should be operated by the
protective devices or by low pressure in the hydraulic system for applying the brakes. The braking
system should be arranged so that
a)
brakes apply on loss of electrical, hydraulic, or pneumatic power;
b)
brakes are applied by control levers that are pulled, unless brake and control power functions
are integrated in the same lever;
c)
brake weights installed to provide auxiliary braking force can be readily tested for freedom of
movement; and
d)
brakes decelerate the hoist at a rate greater than 1.5 m per second per second, and less than
3.7 m per second per second where braking is initiated by the protective circuit and the hoist
is
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i)
normally used to transport persons; and
ii)
operating in the normal full-speed zone.
For existing hoists with deceleration rates exceeding 3.7 m per second per second, and where it is
practicable to do so, the braking system should be modified to reduce the deceleration rate to 3.7 m
per second per second or less.
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Annex D (informative)
Maintenance
Note: This informative Annex has been written in mandatory language to facilitate adoption by anyone
wishing to do so.
D.1 General
In order for electrical equipment to operate in a safe and reliable manner, it shall be maintained in
accordance with CSA Z463.
Note: For proper maintenance and testing methods, see CSA Z463, CSA Z462, CSA Z460, IEEE Std 450,
ANSI/NETA MTS, NFPA 70B, and Gill (2009). CSA Z463 has been developed to improve safety for worker
and protection of property through the adoption and systematic application of maintenance strategies for
electrical equipment and promotes the importance of maintenance of electrical systems. CSA Z463 is part of
the CSA Z460 series, which constitutes a comprehensive trilogy of electrical safety publications, consisting of
CSA Z460, CSA Z462, and CSA Z463.
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D.2 Electrical insulation
Insulation shall be kept clean and dry. Condensation on de-energized electrical apparatus, collection
of conductive dust, and the presence of chemical contamination (diesel soot) has led to insulation
failure. Collection of dust also inhibits the proper cooling of conductors and can reduce the speed of
mechanical mechanisms, resulting in overheating or improper coordination.
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Annex E (informative)
Electrical installations in ammonium nitrate fuel oil (ANFO) areas bulk
powder magazines
Notes:
1)
This Annex is not a mandatory part of this Standard.
(1)
This informative Annex has been written in normative language to facilitate adoption by anyone
wishing to do so.
2)
The information in this Annex has been was originally supplied by Orica Explosives Technology and
Vale and has been since modified.
E.1 Introduction
This Annex deals with surface or underground mining environment electrical installations for bulk
powder magazines in which where ammonium nitrate fuel oil (ANFO) explosives are present
during storage, transfer, or handling stored and handled for transfer in surface or underground
mining environments.
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Although the requirements for wiring methods specified in Clause 4.3.5.1 adequately address needs
related to typical explosives storage magazines, the properties of ANFO-based explosives require a
unique approach to the wiring methods for hazardous locations in addition to those specified in the
Canadian Electrical Code, Part I. The guidelines normally consulted by electrical designers and
constructors in the mining industry are not adequate to ensure safe electrical installations in bulk
storage powder magazines areas where ANFO might be present.
This Annex does not constitute a detailed design for construction but rather is intended to be used as
a guideline by the designer. Figures E.1 to E.3 supply applicable extracts from Natural Resources
Canada’s Storage Standards for Industrial Explosives, Natural Resources Canada’s Guidelines for Bulk
Explosives Facilities — Minimum Requirements, and an informational resource for the designer. In
addition to the electrical installation considerations summarized in Clause E.3, designers should
always refer to, and become familiar with, the minimum requirements for these classified locations
from
a)
NRCan G05-01;
b)
NRCan G05-02; and
c)
the Canadian Electrical Code, Part I.
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E.2 Background
E.2.1 ANFO explosives
Ammonium nitrate (AN) is the primary oxidizer used in the production of ANFO mixtures. As a
packaged or emulsified blasting agent, it is widely used at surface and underground mining
operations in dry boreholes and the dry top portion of holes containing water, or pneumatically
loaded into small-diameter horizontal and inclined boreholes.
E.2.2 Tetra-ammine copper nitrate (TACN)
Tetra-ammine copper nitrate is an impact-sensitive explosive compound that can present a hazard
during the operation of ammonium nitrate (porous prill and emulsion) storage and handling
facilities. Users of ammonium nitrate emulsions and ammonium-nitrate-based bulk explosives
products need to be aware of safety information on
a)
the properties of TACN, in particular how TACN forms, what it looks like, and its relative
impact sensitivity;
b)
locations where TACN can form;
c)
the consequences of the presence of TACN;
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d)
how to reduce the risk of TACN; and
e)
how to remove TACN contamination.
The chance of forming TACN can be virtually eliminated through engineering design standards and
appropriate management systems.
It should be noted that during normal emulsion storage and pumping operations, unprotected
copper or copper alloy parts can remain in pristine condition. Emulsion breakdown, however, can
stimulate TACN production.
E.2.3 General properties of TACN
TACN is a complex copper compound that is identified by the presence of blue crystals on copper or
copper alloy (e.g., brass or bronze) surfaces. These crystals differ slightly in the depth of the blue
colour, with some samples of TACN appearing almost purple. The difference in colour is believed to
be caused by different water levels in the TACN.
E.2.4 Formation of TACN
TACN forms when copper or copper alloy parts come into contact with an aqueous solution of
ammonium nitrate. Its formation can occur under two circumstances:
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a)
ammonium nitrate spillage or dust deposits on a copper or copper alloy surface in locations
where the atmospheric humidity exceeds the critical relative humidity (CRH) of ammonium
nitrate. For practical purposes this CRH can be regarded as about 65%; or
b)
a water-in-oil-type emulsion where the aqueous phase is a concentrated solution of
ammonium nitrate suffers a breakdown that exposes copper or copper alloy pump and pipework parts to an ammonium nitrate solution.
E.2.5 Explosive properties of TACN
As TACN is not a commercially or militarily useful explosive, its characterization in the literature is
limited. The following, however, is known about the explosive characteristics of TACN:
a)
TACN has an impact sensitivity slightly lower than that of lead azide and dry PETN
(pentaerythritol tetranitrate), but higher than TNT (trinitrotoluene);
b)
TACN is not friction sensitive (as determined by the BAM [German Federal Institute for
Testing Materials] friction test);
c)
if detonated, TACN is a quite powerful explosive (81% TNT); and
d)
TACN explodes at 330 °C.
Of particular concern is the high impact sensitivity of TACN, as indicated in the following Table:
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E.2.6 Locations where TACN can form
E.2.6.1
In ammonium nitrate storage and handling areas, TACN can form on
a)
brass junction boxes and gland sealing nuts;
b)
brass fittings on pneumatics;
c)
exposed copper water pipes, e.g., drinking water and safety shower pipes;
d)
connectors to battery packs for ammonium-nitrate-handling machinery e.g., forklifts and
front-end loaders; and
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e)
exposed sections of copper grounding and bonding conductors.
E.2.6.2
In emulsion pumps, tanks, hoses, and pipelines, TACN can form on
a)
brass internal air valves and silencer meshes (diaphragm pumps);
b)
brass caps on tanks and/or brass flame trap meshes;
c)
brass camlock wings and pins on hoses carrying emulsions; and
d)
the internal parts of valves.
E.2.6.3
On mobile manufacturing processing units (MMUs MPUs), TACN can form on
a)
brass camlock wings and pins on hoses carrying emulsions;
b)
internal parts of valves coming into contact with emulsion;
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c)
connectors to battery packs;
d)
standard zinc-plated hydraulic fittings; and
e)
brass fittings on braking systems.
Note: An MPU is a vehicle in which an explosives manufacturing operation is carried out, or a portable
machine used to carry out a manufacturing operation. NRCan G05-02 MMU is a mobile or transportable
mixing or delivery unit for the preparation of the finished explosive. In its Guidelines for Bulk Explosives
Facilities — Minimum Requirements, the Explosives Regulatory Division of Natural Resources Canada
considers an ANFO pneumatic delivery system with a capacity of 100 kg or more to be an MMUMPU.
E.2.6.4
Due to their high frequency of use, it is unlikely that TACN will form on hand-held tools used in
loading blast holes (e.g., weights used for dipping holes, tools used for checking collar heights, and
mirrors used for checking drilling for “belling”). It is prudent, however, to regularly check such
items for the presence of TACN.
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E.2.7 Consequences of the presence of TACN
E.2.7.1 Ammonium nitrate storage and handling areas
TACN is generally not found in a large enough quantity or in close enough proximity to ammonium
nitrate inventories to create a risk of propagation of a TACN explosion. In any event, oxidizinggrade ammonium nitrate is not considered to be detonator sensitive. The risk, therefore, in
ammonium nitrate storage and handling areas is from a small local explosion that could seriously
injure a tradesperson working on TACN-contaminated equipment. Externally occurring TACN can
be easily seen and cleaned off, but hollow sections and internally occurring TACN (such as in brass
junction boxes) pose a more significant and less obvious hazard. It is therefore important for
maintenance workers to be aware of TACN and know how to remove TACN contamination. They
should never use impact or hot-work tools on an item known or suspected to contain TACN.
E.2.7.2 Emulsion pumps, tanks, hoses, and pipelines
TACN is unlikely to form when copper or copper alloy parts are in contact with stable water-in-oil
emulsions. However, emulsions do break down with age and other factors. This breakdown creates
the opportunity for concentrated ammonium nitrate solution to directly make contact with the
copper or copper alloy. TACN formed in this manner is in intimate contact with inventories of
explosive precursors, i.e., in intimate contact with a powerful oxidizer/fuel mixture that needs only a
controlled density reduction to form a Class 1 explosive. For this reason, copper or copper alloy
parts should be positively eliminated from piping, valves, venting, or pumping of explosives
precursors.
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E.2.7.3 Mobile manufacturing processing units
The points discussed in Clauses E.2.7.1 and E.2.7.2 for ammonium nitrate and emulsion storage and
handling apply equally to MMUs MPUs. It is strongly recommended that copper or copper alloy
parts should be positively eliminated from piping, valves, venting, or pumping of explosive
precursors on MMUs MPUs. This is strongly recommended.
E.2.8 Reducing the risks of TACN
To reduce the risks of TACN, the following recommendations should be followed by all users of
ammonium nitrate, emulsions, and ammonium-nitrate-based bulk explosive products:
a)
replace all copper and copper alloy fittings in ammonium nitrate and emulsion storage and
handling facilities with copper-free materials (e.g., stainless steel, aluminium, or plastic,
where climatically suitable);
b)
replace copper and copper alloy fittings on MMUs MPUs with copper-free materials. If a
copper or copper alloy fitting on an MMU MPU cannot be replaced with an alternative
material (e.g., brass fittings associated with truck braking systems), it needs to be painted
with a two-part epoxy paint;
c)
paint copper or copper alloys external to buildings but within 5 m of ammonium nitrate or
emulsion-handling systems with two-part epoxy paint;
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d)
review workshop procedures to ensure that no copper-containing jointing compounds or
anti-seize compounds are used in ammonium nitrate and emulsion storage facilities or
MMUs MPUs (e.g., nickel-based compounds are suitable);
e)
train maintenance workers to identify TACN, remove TACN contamination, and never use
impact or hot-work tools on an item known or suspected to contain TACN; and
f)
include the recommendations in Items a) to e) in engineering standards.
E.2.9 Removing TACN contamination
TACN corrosion can be removed by soft brush painting using a mixture of one part spirit of salts
(35% hydrochloric acid) and ten parts water. When this process is complete the surface should be
flushed with water.
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E.3 Electrical installations in ANFO storage magazines
E.3.1 General
Due to the unique hazard posed by the potential formation of TACN on and around electrical
equipment installed in a magazine in which ANFO is stored and handled, Clauses E.3.2 to E.3.4
summarize design considerations that are intended to minimize the potential formation of TACN.
Their incorporation into the design of electrical installations within magazines is strongly
recommended.
The general principles in Clauses E.3.2 to E.3.8 describe considerations for electrical installations in
bulk ANFO magazines located in underground mines. The same general principles can be applied to
electrical installation designs for such magazines at a surface mine and for the onboard systems of
MPUs.
E.3 Guidelines for powder magazine electrical design
E.3.2 Wiring methods method considerations
The following requirements shall considerations apply to wiring methods:
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a)
exposed copper, brass, or other copper alloys shall must not be installed inside the magazine.
Where the use of these materials is unavoidable, exposed components must be protected by
painting with a two-part epoxy; no electrical installation can extend to within 5 cm above the
floor;
(b)
the requirements of Section 18 of the Canadian Electrical Code, Part I, that apply to Class II,
Division 2 hazardous locations shall be followed, except for the floor and up to 5 cm above
the floor, which shall be classified as Class I, Zone 2;
b)
aluminum-armoured Teck cable and aluminum cable glands or rigid aluminum conduit shall
must be used for fixed wiring. Steel-armoured Teck cable and galvanized steel cable glands
shall must be avoided. Where the use of galvanized steel cable glands and fittings is
unavoidable, exposed components must be protected by painting with a two-part epoxy;
c)
all cable glands shall must be approved suitable for Class II, Division 2 the application;
d)
power and lighting conductors shall must be a minimum of No. 12 AWG copper;
e)
fixed cabling shall must be installed in such a way that it is mechanically protected from
damage or protected by location;
f)
cables shall must not be run within 150 cm of the finished floor. Additional mechanical
protection shall must be provided where vertical runs come within 150 cm of the floor;
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g)
where the Canadian Electrical Code, Part I, requires a minimum of Type 4 enclosures inside the
magazine, Type 4X shall must be used. All fasteners shall must be securely tightened; and
h)
lighting circuit voltage shall must not exceed 120 V and be protected by a 15 A Class A
ground-fault circuit interrupter.
E.3.3 Grounding and bonding
The following requirements shall considerations apply to grounding and bonding:
a)
all nonelectrical metallic frames, rails, and structures such as steel racks shall must be bonded
inside the powder magazine using No. 2/0 AWG aluminum conductors;
b)
connections for aluminum bonding conductors to equipment shall must be made with
approved copper-free connectors using an oxide-inhibiting compound on all aluminum
connections;
c)
connections for aluminum bonding conductors to the systems ground conductor shall must
be made with approved copper-aluminum-compatible connectors; and
d)
bonding conductors shall must be run in such a way that they are protected from mechanical
damage.
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E.3.4 Messenger-supported cabling systems
When messenger-supported cabling systems are used inside a magazine,
a)
the messenger cable should be 1/4 in stainless steel aircraft cable; and
b)
electrical cables should be supported with 100% plasticized coated steel cable clips.
E.3.5 Disconnecting means
With regard to disconnecting means, it should be possible to isolate all power to the magazine from
one accessible location outside of the magazine. In addition, switches shall must be grouped
together and clearly identified as to their purpose, including the type and maximum rating of
overcurrent protection permitted for the circuit.
E.3.6 Cranes and crane circuits
The following requirements shall considerations apply to cranes and crane circuits:
a)
all elements of the crane/hoist assembly shall must be suitable for use in a Class II, Division 2
the location where ANFO dust can accumulate;
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b)
the hoist shall must have a load limiter to prevent overloading the structural and mechanical
components;
c)
for 600 V rated cranes, the power supply shall must be from a resistance-grounded source (15
A maximum GF current), complete with neutral grounding resistor monitoring and GF
protection with 2 A maximum trip and 100 ms maximum instantaneous trip;
d)
a fused switch incorporating current-limiting fuses rated 10 A or less shall must be installed
in the crane supply circuit to limit peak let-through current in the event of a short circuit;
e)
the local nonfused crane disconnect switch disconnecting means required by Rule 40-008 of
the Canadian Electrical Code, Part I, shall must be
i)
rated Type 4X;
ii)
located between the entrance to the magazine and the explosives storage area in such a
way that the switch is accessible at all times but protected from physical damage; and
iii)
mounted with the bottom of the enclosure at a minimum of 150 cm above the finished
floor;
f)
extra-hard-usage flexible cords and cable glands suitable for the application may be used;
(f)
flexible cords may be used as follows if they meet the requirements specified for Class II,
Division 2 locations in the Canadian Electrical Code, Part I:
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i)
for a hoist pendant control where the 120 V crane control circuit is protected by a Class
A ground-fault circuit interrupter; and
ii)
as part of a festoon system for an electric hoist. Care shall must be taken to ensure that
the mechanical stops for crane motions prevent the festoon system or any part of the
hoist or crane from making contact with the wall or other obstacles; and
g)
procedures shall must be developed and implemented to ensure that
i)
the pendant will not be snagged by mobile equipment;
ii)
there will be no movement of equipment unless the crane is parked at a designated
location with the pendant located out of harm’s way; and
iii)
mobile equipment is examined for protuberances that might snag the pendant.
Measures shall must be taken to reduce this risk.
E.3.7 Signs
Signs shall must be posted in the magazine to remind users of the operating procedures to be
followed.
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E.3.8 Maintenance
Maintenance procedures shall must include
a)
cleaning up spills as they occur;
b)
inspection and cleaning of electrical equipment and enclosures to prevent buildup of dust;
and
c)
measures to ensure the integrity of the enclosures and connectors.
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Annex F (informative)
Options for equipment control power
Note: This Annex is not a mandatory part of this Standard.
F.1 General
This Standard requires that the protective systems be of a fail-safe nature. This Standard also
specifies undervoltage tripping. Both of these requirements can be influenced by the choice of the
control power provided for operation of the protective, interrupting, or controlling devices (e.g.,
relays, circuit breakers, contactors).
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There are a number of possible choices for the supply of control power to electrical distribution
equipment, which involve the balancing of cost against reliability. When selecting the control power
source, it should be evaluated as to the risks it might or might not introduce in conjunction with the
supply needs of the protective relaying, control scheme elements, and the final power circuit
interrupting device needs. Specific attention should be given to the reliability of the control source to
be available when it is needed to activate the protective requirements of the system. Attention
should also be given to the overall scheme to ensure a segment of the power system remains deenergized until it can be deemed safe to re-energize. If a control power source is of the type that is
available when the power system is not energized, the energization and appropriate distribution of
power throughout the network should be examined to ensure risks are mitigated. The power-up of a
system and the shutdown or loss of a portion of the system, for various lengths of time, are
eventualities for which the risks should be evaluated and any safety concerns mitigated from the
perspective of the interrupting device choices, the protective and controlling elements, and how
these all interact.
Of the four control power source type choices discussed here, the capacitive trip device cannot
supply continuous power to devices (it is essentially a one-shot device), while the other three
options can all supply continuous power.
F.2 Capacitive trip device (CTD)
The CTD is a short time (non-continuous) method of providing trip power to (usually) circuit
breakers, but can also be used for some other small devices (e.g., a lockout relay). There are a wide
variety of designs available.
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CTDs are typically used in very small installations where it is not cost effective to provide other
sources of control power (e.g., installations of one or two circuit breakers). The most common CTDs
usually provide one-time trip between 5 and 40 s (approximate) after the loss of primary power,
typically for one device only (e.g., a trip coil on one circuit breaker is one device). Some CTDs have
larger capacitors that allow for up to two consecutive trips of the same trip coil, to power two
separate trip coils, or to energize trip coils requiring a large amount of activation energy. There are
some designs of CTDs which use a battery to assist in retaining the capacitors’ charge for a longer
time, up to approximately three days in some cases. Using modern low leakage capacitors and
blocking diodes, some CTDs can retain a usable charge for over 100 h. In all cases, CTDs should be
considered as one-time, or at most two-time, use before requiring recharging and they cannot be
used to supply pilot lights or monitoring relays. Recharging time, once reconnected to a source of
power, is usually quite short (a few seconds). A CTD requires a method to safely discharge the
capacitors for maintenance purposes (the charge left on the capacitor can be lethal if not properly
discharged), and units with battery assist need to have the health of the battery checked as part of
regular maintenance.
F.3 AC supply
AC supply is the easiest constant supply system to implement, but considered to be the least reliable
of the options as it is typically totally dependent on the main supply itself. If the main power source
is lost due to an outage, the control power immediately disappears. The control power is taken from
a voltage transformer (VT) connected to the main bus, or for higher power requirements, a control
power transformer is installed. In some cases, an alternative ac supply may be obtained from
another source different from the equipment under scrutiny, although ultimately it is still likely
derived from the same utility feeder, and so whether the alternative source is available depends on
which protective device (e.g., overcurrent relay) has caused the outage — if the utility incomer is the
cause, then overall reliability is not improved. All of the control devices, including pilot lamps,
protective relays, metering devices, trip, and close coils etc., are selected to be ac rated.
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F.4 Uninterruptible power supply (UPS) system
The UPS system generally consists of one or more small UPS systems, almost always single phase,
which obtain their power from an ac supply and supply emergency ac power from their internal
batteries when the main supply has an outage. When operating on battery power, the units take
their operating power for the dc to ac converter from the same set of batteries, leading to an
overhead energy cost which works to deplete the batteries even if little power is being drawn by the
load. Generally a small UPS system can provide power durations of up to several tens of minutes
before the batteries are depleted. Larger UPS systems can extend the duration of the emergency
supply, but can easily become more costly than the straight battery system described below.
Batteries must be checked regularly during a regular maintenance program. Some small UPS
systems can generate a fairly high number of output harmonics (i.e., the ac output while on battery
is not “clean”), which can negatively affect some electronic devices connected as a load. There are
several factors that will reduce the UPS operating time from the design value because of reduction in
battery capacity:
a)
if the load on the UPS system is greater than was anticipated;
b)
if there was only intermittent use of the UPS prior to the supply failure (batteries need to be
cycled occasionally for best life);
c)
if the batteries were not fully charged;
d)
if the batteries are old, their capacity will be reduced; and
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e)
UPS systems introduce additional complexity to the control system and this additional point
of failure can reduce the overall system reliability.
F.5 DC battery
The dc battery is generally considered to be the most reliable continuous supply system, but also the
most costly. The battery system is sized taking into account the load of all the control devices as well
as the duration required to maintain the supply. The system consists of a battery bank and a battery
charging system, which takes up floor space (how much depends mostly on the size of the battery
bank). All of the control devices, including pilot lamps, protective relays, metering devices, trip and
close coils etc., are selected to be dc rated, so there is no need to convert the dc to ac (saving the
energy overhead cost of the conversion that occurs with the UPS option). The dc current, as it comes
directly from the battery, is clean dc. Durations are commonly selected to be for many hours and
sometimes even several days for extremely critical equipment. The batteries need to be maintained,
and need to be replaced on occasion (there are different types of batteries offered, and therefore
maintenance intervals and expected life can vary).
F.6 Summary of the control power types
Table F.1 briefly summarizes the available choices.
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Table F.1
Summary of the control power types
(See Clause F.6.)
(New)
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F.7 Other considerations
The choice of the source of control power impacts other installed components in the equipment as
well. For example, modern microprocessor controlled metering systems and protective relays are
not instantly available on power-up. They require a certain amount of time to implement their boot
routines and their initial self-checking routines before they are ready to perform their primary
functions. This time can vary depending on the particular relay, but is generally between 10 to 45 s.
This delay can be an issue for a cold start of equipment that has just had its power source reestablished after an emergency outage, but whether it is actually important depends on the process
being controlled and the urgency to restore power to the load. Protective relays that have remained
powered with dc power from a battery system throughout the outage will be ready to function
immediately. Protective relays powered through UPS systems within the window of supply of the
UPS will be ready to use, but outside of that window will be the same as if starting from a cold start.
Protective relays that were powered though ac power derived from the main power supply will
undergo a cold start and will need time to regain their functionality.
Although only applicable to certain processes, the choice of control power might also be important
in the ease of setting up a particular system prior to recovery from an outage. Some processes
require circuit breakers and other devices to be open or closed in a certain configuration or sequence
for that process to start properly. While all circuit breakers can be open or closed manually, it might
be considered important to be able to operate those devices remotely even before the main power is
restored. The choice of a dc battery system, or perhaps a UPS system, provides that remote setting
possibility.
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CTD-type control power systems are typically more associated with shunt-tripping type systems
and not typically used (nor recommended to be used) for portions with an undervoltage tripping
scheme involving an undervoltage release coil or relay, as associated with meeting the fail-safe
requirements within this Standard. An ac supply type control power system, without the addition of
a CTD, UPS, batteries, other energy storage means, or by being powered from a reliable ac source
that is separate from the controlled power system, cannot be used for a shunt-tripping type system.
The ac supply type control power system can be used for the portions with an undervoltage tripping
scheme as associated with meeting the fail-safe requirements within this Standard. Where UPS,
batteries, or other energy storage means are used for a the control power system or the control
power is being sourced from a reliable ac source that is totally separate from the controlled power
system, either shunt-tripping or undervoltage tripping may be used, but for meeting fail-safe
requirements it should be ensured that the sustained availability of the control power should not
bypass any undervoltage tripping needs for the circuit when the main power system is lost. Also,
when the interrupting or power controlling elements are bi-stable in nature (i.e., mechanically or
magnetically latched) and can independently remain closed even when the main power system is
lost or where automatic re-closing can be contemplated, the risks involved with re-energization of
the system must be evaluated and mitigated. These re-energization risks should be particularly
evaluated where mobile equipment is involved or where overhead lines might be accidentally
contacted by equipment at the mine.
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Annex G (informative)
Equipment protection levels and methods of explosion protection for
underground coal mines
Note: This Annex is not a mandatory part of this Standard.
G.1
Group I electrical equipment is equipment that is approved for use in underground coal mines,
when using the IEC 60079 series of standards as the basis for approval. Equipment that is approved
for Group I will have been assessed for safe operation in combustible (methane-air) atmospheres, as
well as combustible (coal) dust atmospheres. Group I equipment is also assessed for maximum
surface temperatures, to take into account the hazard of layers of coal dust accumulating on heatproducing equipment. The maximum allowable surface temperature for Group I is 150 °C. IEC
recently introduced the concept of the equipment protection levels (EPL) system, which was
introduced because it allowed for more versatile solutions to be applied to explosion protection
issues. In addition, although not relevant to this Standard, the EPL system is also being used for
non-electrical equipment such as mechanical equipment covered by ISO standards. This now allows
for a consistent risk-based approach to be taken toward explosion protection, covering all types of
equipment, both electrical and non-electrical.
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G.2
It is important to note that this Standard does not exclusively require that equipment be assessed for
Group I compliance with the IEC 60079 series of standards. Equipment approved by the United
States Mine Safety and Health Administration (MSHA) is not assessed to IEC standards, and does
not involve the EPL system or Group I designation but generally does provide an equivalent level of
safety. Other than explosion-proof and intrinsically safe, MSHA does not specifically categorize
equipment according to the various available methods of explosion protection being used in the IEC
system. MSHA-approved intrinsically safe equipment uses the two-fault assessment criteria and
therefore is equivalent to the Group I Ex ia method of explosion protection (providing a “very high”
level of safety), and MSHA-approved explosion-proof enclosures and motors provide protection
equivalent to the Group I Ex d method of explosion protection. From a legal standpoint, the
authority of MSHA extends only within the United States of America and as such, MSHA does not
have any legal status as an approval body outside of the United States, and only MSHA can approve
products using its own MSHA requirements. By contrast, numerous agencies around the globe can
approve equipment using essentially the same set of standards (the IEC 60079 series). Each country
might have its national deviations to IEC standards, but these deviations tend to be minor.
G.3
Group I equipment is now further subdivided into two categories of explosion protection, EPL Ma
which provides a “very high” level of explosion protection, and EPL Mb which provides a “high”
level of explosion protection. The following extract from Appendix D of IEC 60079-0 provides
further explanation:
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D.2.1 Mines susceptible to firedamp (Group I)
D.2.1.1 EPL Ma
Equipment for installation in a mine susceptible to firedamp, having a “very high” level of
protection, which has sufficient security that it is unlikely to become an ignition source in
normal operation, during expected malfunctions or during rare malfunctions, even when left
energized in the presence of an outbreak of gas.
Note: Typically communications circuits and gas detection equipment will be constructed to meet the
Ma requirements — for example an Ex ia telephone circuit.
D.2.1.2 EPL Mb
Equipment for installation in a mine susceptible to firedamp, having a “high” level of
protection, which has sufficient security that it is unlikely to become a source of ignition in
normal operation or during expected malfunctions in the time span between there being an
outbreak of gas and the equipment being de-energized.
Note: Typically Group I equipment will be constructed to meet the Mb requirements — for example
Ex d motors and switchgear.
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G.4
Currently, in terms of one single method of explosion protection, only intrinsic safety Ex ia
equipment qualifies as having the Ma level of equipment protection. This is because Ex ia equipment
is required to remain safe even when subjected to two internal independent faults, thereby
providing a very high level of confidence in such equipment not presenting an ignition hazard, even
under fault conditions.
All other types of equipment, such as equipment housed in an explosion-proof Ex d enclosure, do
not qualify for EPL Ma, as shown in Table G.1.
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Table G.1
Explosion protection — Levels and types
(See Clauses G.4 and G.5.)
(New)
Note: For a description of the above explosion protection methods, see Figure G.1 for the applicable extracts
from Canadian Electrical Code, Part I, of the Appendix B, notes to Rules 18-100 and 18-150.
G.5
Not all equipment will be marked with the EPL designation. The EPL designation was a relatively
recent introduction to the IEC system, so older equipment will not be marked with the EPL
information. If there is no specific EPL marking, Table G.1 can be used as a guide for assessing the
suitability of a given method of explosion protection relative to a given EPL.
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G.6
The EPL system is versatile in that it allows for explosion protection methods to be combined, to
provide a higher level of protection. The following are provided as some of the combinations that,
depending on the application, may be possible:
a)
inductive transmitters (for example proximity switches, electrical position sensors) with
intrinsic safety “ib” enclosed by encapsulation “mb”. The connections to intrinsically safe
“ib” circuits can be protected by the increased safety “e”;
b)
a lamp with the bulb designed as increased safety “e”, the lamp circuit with the switch as
intrinsic safety “ib”. These components may be incorporated in a flameproof enclosure “d”;
c)
measuring transducers with intrinsic safety “ib” and a flameproof enclosure “d”;
d)
equipment with electrical circuits of intrinsic safety “ib”, additionally protected by a powder
filling “q”;
e)
electromagnetic valves with encapsulation “mb”, enclosed by a flameproof enclosure “d”;
and
f)
increased safety “e”, with pressurized equipment “px”.
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Figure G.1
Extracts from the Canadian Electrical Code, Part I, of Appendix B notes
related to Rules 18-100 and 18-150
(See Clause G.4 and Table G.1.)
[Appendix B notes for] Rules 18-052, 18-090, 18-100, and 18-150
The 2011 edition of CAN/CSA-C22.2 No. 60079-0 [adopted IEC 60079-0 (fifth edition, 2007-10)]
introduces “equipment protection levels” (EPLs) as a required marking on hazardous location
electrical equipment certified to the IEC 60079 series of Standards. This marking will appear on new
electrical equipment approved under the adopted 60079 series of Standards. For older equipment, in
stock or in the field, that does not include the EPL marking, suitability for the intended zone will
continue to be determined by the types of protection. EPLs will enable users to identify the zone(s)
in which the IEC 60079 type of hazardous location electrical equipment can be used, without having
to identify the zone by the types of protection used.
EPLs provide an indication of the suitability of electrical equipment for each zone. Further
information on EPLs can be found in CAN/CSA-C22.2 No. 60079-0. The following table shows the
acceptable EPLs for Zones 0, 1, and 2.
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(New)
[Appendix B notes for] Rules 18-054 and 18-150
Equipment of the heat-producing type is currently required by product Standards to have a
temperature code (T-Code) marking if its temperature exceeds 100 °C. However, for equipment
manufactured prior to the T-Code requirement and motors applied in accordance with Rule 18-150,
there may be no such marking. Therefore, the suitability of older hazardous locations equipment of
the heat-producing type and motors applied in accordance with Rule 18-150 should be reviewed
prior to being installed in a hazardous location to ensure compliance with Rule 18-054. For the
purpose of this Rule, equipment such as boxes, terminals, fittings, and resistance temperature
detectors (RTDs) are not considered to be heat-producing devices.
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[Appendix B notes for] Rules 18-090, 18-100, and 18-150
Equipment certified for hazardous locations is marked with the area classification where the
equipment can be installed. For example, a piece of equipment marked with Class I may be installed
in a Class I location. This Code recognizes the IEC system of marking equipment as providing a
specific type of protection. This equipment may be installed only in locations where this type of
protection is recognized. For example, Rule 18-100 recognizes that equipment marked with the type
of protection “d” is acceptable for installation in a Class I, Zone 1 location. Additional information
related to types of protection may be found in the CAN/CSA-C22.2 No. 60079 series of Standards
listed in Appendix A
The following table is provided to illustrate some of the equipment and types of protection
permitted in the three Zones. This Table is not intended to be comprehensive. Other equipment may
be permitted by specific Rules (e.g., fuses in Rule 18-150).
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(New)
* Equipment may be certified to CAN/CSA-C22.2 No. 60079-1.
[Appendix B note for] Rule 18-100
Equipment marked for Class I, Division 1 is suitable for use in Zone 1 and Zone 2.
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[Appendix B notes for] Rules 18-100 and 18-150
The following briefly explains the various types of protection used in the Zone system. For further
information see the applicable CE Code, Part II Standards.
a)
Intrinsically safe (intrinsic safety) (i, ia, or ib): a type of protection based on the limitation of
electrical energy to levels where any open spark or thermal effect occurring in equipment or
interconnecting wiring that may occur in normal use, or under fault conditions likely to occur
in practice, is incapable of causing an ignition. The use of intrinsically safe equipment in a
hazardous location also requires that associated wiring and equipment, which is not
necessarily located in a hazardous area, be assessed as part of any intrinsically safe system.
The primary difference between equipment marked Ex ia and Ex ib is that equipment marked
Ex ia must continue to provide explosion protection after two faults have been applied,
whereas equipment marked Ex ib must continue to provide explosion protection after one
such fault has been applied (see CAN/CSA-C22.2 No. 60079-11).
b)
Flame-proof (d): a type of protection of electrical apparatus in which the enclosure will
withstand an internal explosion of a flammable mixture that has penetrated into the interior,
without suffering damage and without causing ignition, through any joints or structural
openings in the enclosure of an external explosive atmosphere consisting of one or more of
the gases or vapours for which it is designed (see CAN/CSA-C22.2 No. 60079-1).
c)
Increased safety (e): a type of protection by which additional measures are applied to an
electrical apparatus to give increased security against the possibility of excessive
temperatures and of the occurrence of arcs and sparks during the service life of the
apparatus. It applies only to an electrical apparatus, no parts of which produce arcs or sparks
or exceed the limiting temperature in normal service (see CAN/CSA-C22.2 No. 60079-7).
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d)
Oil immersed (o): a type of protection in which electrical apparatus is made safe by oil
immersion in the sense that an explosive atmosphere above the oil or outside the enclosure
will not be ignited (see CAN/CSA-C22.2 No. 60079-6).
e)
Pressurized (p): a type of protection using the pressure of a protective gas to prevent the
ingress of an explosive atmosphere into a space that may contain a source of ignition and,
where necessary, using continuous dilution of an atmosphere within a space that contains a
source of emission of gas that may form an explosive atmosphere (see CAN/CSA-C22.2 No.
60079-2).
f)
Powder-filled (sand-filled) (q): a type of protection in which the enclosure of electrical
apparatus is filled with a mass of granular material such that, if an arc occurs, the arc will not
be liable to ignite the outer flammable atmosphere (see CAN/CSA-C22.2 No. 60079-5).
g)
Encapsulation (m): a type of protection in which parts that could ignite an explosive
atmosphere by either sparking or heating are enclosed in a compound in such a way that this
explosive atmosphere cannot be ignited (see CAN/CSA-C22.2 No. 60079-18).
h)
Non-sparking, restricted breathing, etc. (n): a type of protection applied to an electrical
apparatus such that, in normal operation, the apparatus is not capable of igniting a
surrounding explosive atmosphere, and a fault capable of causing ignition is not likely to
occur (see CAN/CSA-C22.2 No. 60079-15).
Note: Type of protection “n” includes a number of means of providing protection. In addition to nonsparking, component parts of apparatus that in normal operation arc, spark, or produce surface
temperatures of 85 °C or greater may be protected by one of the following:
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a)
enclosed break devices;
b)
non-incendive components;
c)
hermetically sealed devices;
d)
sealed devices;
e)
energy-limited apparatus and circuits; or
f)
restricted breathing enclosures.
Some of these methods are similar to methods previously allowed in Class I, Division 2
locations. To better understand the various methods allowed under type of protection “n”,
refer to CAN/CSA C22.2 No. 60079 15.
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Annex H (informative)
Underground coal mine ac system grounding considerations
Note: This Annex is not a mandatory part of this Standard.
H.1
Particularly as related to Clause 7.10.3 for underground coal mines, the following items should be
considered in relation to the ac system grounding:
a)
Neutral grounding impedances, listed in Appendix B of Section 10-1100 of the Canadian
Electrical Code, Part I, include grounding resistors, grounding transformers, ground fault
neutralizers, reactors, capacitors, or a combination of these. In some cases, neutral-connected
ground fault limiting reactive devices (inductive or capacitive) can give rise to detrimental
harmonics and transient voltages.
b)
The power factor of the ground fault limiting impedance, assuming zero capacitance, should
not be less than 0.65 lagging, and should limit the inrush current to a maximum of 1.6 times
the designed steady state ground fault limited current.
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c)
In underground coal mines, the prospective ground fault current, and the ground fault
voltage, should be reduced to as low a value as possible; values of 25 V ac or 60 V dc are
desirable. Different protection levels should be coordinated to achieve as fast a fault clearance
time as possible.
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Annex I (informative)
Flame test ratings
Note: This Annex is not a mandatory part of this Standard.
I.1
Table I.1 gives a brief overview of the various CSA flame test ratings. The included brief summaries
of the test procedure and pass criteria are meant to only give an introductory level of understanding
for the various flame tests and their relative severity. For the full requirements, see the referenced
publications.
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Table I.1
Flame test ratings
(See Clause I.1.)
(New)
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(Deleted)
Figure E.1
Extracts from Natural Resources Canada’s
Storage Standards for Industrial Explosives
(See Clause E.1.)
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(Deleted)
Figure E.1 (Continued)
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(Deleted)
Figure E.1 (Continued)
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(Deleted)
Figure E.2
Extracts from Natural Resources Canada’s Guidelines for Bulk
Explosives Facilities — Minimum Requirements
(See Clause E.1.)
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(Deleted)
Figure E.2 (Concluded)
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(Deleted)
Figure E.3
Extracts from the Canadian Electrical Code, Part I
(See Clause E.1.)
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