Northparkes Mines experienced an electrical fault inside a 415V switchboard that resulted in an arc flash, damaging the equipment. The incident was contained and no personnel were injured. An investigation found the likely root causes were dust and moisture ingress into the switchboard. Actions taken included replacing damaged components, improving the switchboard's sealing, and auditing electrical equipment to prevent future issues. While lightning strikes have rarely damaged equipment in the past, the site's lightning protection was reviewed. Key learnings centered around thorough investigations, effective protection systems, and applying lessons across operations.

1. • CMOC - Northparkes
Mines
• Introduction – Northparkes &
CMOC
• LV Board Explosion
– Incident Investigation Findings
– Likely Root Causes
– Actions Taken
– Key Learnings
Michael Wood, Senior Electrical Engineer, Northparkes Mines

2. Introduction
2
UNDERGROUND COPPER AND GOLD MINE
JOINT VENTURE OPERATION –
80% CHINA MOLYBDENUM CO., LTD
20% SUMITOMO GROUP (JAPAN)
Joint Venture Operation
80% China Molybdenum Co., Ltd
20% Sumitomo Group
Underground Copper & Gold Mine

3. Introduction
Location
3
PARKES
SYDNEY
NEW SOUTH WALES
NORTHPARKES MINES

4. Introduction
4
LIFT 1
E48
LIFT 2
LOADING
STATION
CRUSHER
0 200 40
0
60
0
80
0
1000
m
E26
EXTRACTION
LEVEL
HOIST

5. Introduction
5

6. Introduction
6

7. Introduction
7
• Secondary Crushing Station in
foreground
• 2.2km curved overland conveyor
in centre of picture
• Stockpiles, Mills and tails dams
in background

8. Introduction
Dual module processing plant 8

9. CMOC’s portfolio
High quality and diversified asset portfolio with strong leverage to China and emerging economies
Sandaozhuang (100%)
Molybdenum / Tungsten
Shangfanggou (55%)
Molybdenum / Iron
East Gobi Project (65%)
Molybdenum
Moly Roaster & FeMo
plants
Shanghai Regional Office
Luoyang City HQ
BeijingXinjiang
CHINA
Henan Province
Sydney
Northparkes (80%)
Copper / gold
Sydney Regional Office
AUSTRALIA
DRCKinshasa
Phoenix, AZ, USA 
Overseas HQ
BRAZIL
Nióbio Brasil Limitada &
Fosfatos Brasil Limitada
(100%)
Niobium and
Phosphates –
Tenke Fungurume
Copper and Cobalt

10. Incident Details – LV board explosion
• Date and Time of Incident: 13/03/17 - 10:56 AM
• Incident Location: 142SW001 415V Switch Room
• Who was involved: No personnel directly involved
• Summary of Incident: Electrical fault inside the
switchboard resulted in an arc flash damaging the
equipment
10

11. Background Information
11
Electrical
Arc Fault
Arc Flash
A
B
C
Ia
Ib
Ic
If
Electrical
System
Damage to
Equipment

12. 12
Switch room
Winder Control
Headframe

13. Incident Details
• Mine control operator reported a loss of network
communications to the surface material handling
equipment. Occurred the same time as a lightning
storm.
• Fire alarm and fire suppression equipment in the E26
switch room had operated.
• 415V Switchboard in the E26 Switch room showed
evidence of arc flash and damage to the equipment.
• Scene preserved, the NSW Resource Regulator was
notified, all clear given to commence investigation and
rectification work 13

14. Incident Details
• The arc flash event was contained inside the 415V
Switchboard and the fault was interrupted by the air
circuit breaker (ACB)
• The switchboard supplies electrical power to the winder
excitation circuit and surface conveyor CV01.
• The repair took 44 hours to complete as ACB and busbar
components were replaced and busbar fabricated
offsite.
• All electrical equipment around the area was checked
for condition, electrical protection and fire systems were
reinstated.
14

15. Photographs
15
Switchboard with panel cover still in place
– arc flash contained
Damage from arc flash inside the
compartment
Evidence of arcing originates in this location

16. 16

17. 17

18. 18

19. 19

20. 20

21. 21

22. 22

23. 23

24. 24

25. 25

26. 26

27. 27

28. Photographs
28
Compartment - after repair New busbar showing method of installation and insulation between
phases

29. What Actions did we take
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Root Cause/Contributing Factor Actions
Dust/Moisture Ingress Reseal board to reinstate IP rating.
Dust/Moisture Ingress Plug opening of the switch room wall on cable entering the room.
Dust/Moisture Ingress Review and update long term online / offline maintenance tactics of switchboards
Voltage Rise Evaluate lightning protection requirement on new installation
Voltage Rise Evaluate and review lightning protection state of existing installations
Dust/Moisture Ingress (Others) Inspect E26 HV switchboard to confirm IP rating
Dust/Moisture Ingress (Others) Audit site switchboards for sealing condition (IP rating)
Voltage Rise (Others) Test switchboard’s transformer oil and excitation transformer oil for sign of voltage stress
Voltage Rise Replace arc flash sensors (potential damage by heat) and reinstate full functionality
Voltage Rise Review and audit status of installed arc flash system

30. Is This a Trend?
• Occurrences of equipment damage from lightning
strikes in the life of the mine?
– 1 occurrence over > 20 years, lightning strike on
headframe damaged underground radio network
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31. Conclusion – Key Learnings
• Investigate thoroughly to determine the root cause
• Ensure protection systems are effective and
maintained
• Apply learnings across the business not just at
incident site
• Good team effort to ensure a safe and timely
recovery
• Engage external expertise where required to assist
(OEM’s, Consultants, RR)
• But wait there is more……………………
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32. AS4730 – Winder Brakes & Control Systems
Standards out for public comment 6/11/17 to 8/1/18
• DR AS/NZS 4730.1:2017 : Mining - Winding equipment -
Winder control systems
• DR AS/NZS 4730.2:2017 : Mining - Winding equipment -
Braking systems
Have a look on the SAI Global website and have your say
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