Department of Consumer and Employment Protection © 2005 Resources Safety 1 Please read this before using presentation This presentation is extracted from content presented at the 2005 Mines Safety Roadshow held in October 2005 It is made available for non-commercial use (eg toolbox meetings) subject to the condition that the PowerPoint file is not altered without permission from Resources Safety Supporting resources, such as brochures and posters, are available from Resources Safety For resources, information or clarification, please contact: or visit

Toolbox presentation: Electrical safety in mining October 2005

Department of Consumer and Employment Protection © 2005 Resources Safety 3 Reporting of electrical accidents Section 78 of MSIA 1994 requires: “every electric shock or burn to a person and every dangerous occurrence involving electricity, to be immediately reported to the District Inspector and recorded in the Record Book kept at the mine” (whether or not an injury or damage has occurred)

Department of Consumer and Employment Protection © 2005 Resources Safety 4 Investigation of electrical accidents Regulation 5.11 of MSIR 1995 requires the appointed “Electrical Supervisor” to investigate, record in the electrical log book and report to the manager, details of every: electric shock or burn to a person fire suspected to be caused by electricity dangerous occurrence involving electricity that could have caused injury to a person

Department of Consumer and Employment Protection © 2005 Resources Safety 5 Reportable occurrences Breakage of rope Railways Presence of gas Gas or dust ignition Explosives Light vehicle incidents Unconsciousness/fuming Cranes Drill/power shovels Fixed plant Rock falls Wall failures Not categorized Electrical Truck/ mobile plant Outbreak of fire Electrical accidents category is ranked 3rd highest

Department of Consumer and Employment Protection © 2005 Resources Safety 6 Electric shocks incidents 1995 – 2004

Department of Consumer and Employment Protection © 2005 Resources Safety 7 Electric shock incidence rates 1995 – 2004 Incidence rate as shocks per 1,000 employees

Department of Consumer and Employment Protection © 2005 Resources Safety 8 Electric shock severity

Department of Consumer and Employment Protection © 2005 Resources Safety 9 Factors affecting electric shock severity Body impedance Current path through the body Shock current magnitude Duration of shock AC or DC supply

Department of Consumer and Employment Protection © 2005 Resources Safety 10 Mining electrical fatalities to October 2005 May 2002 C HarrisNickel Seekers (Daisy Milano Mine) Mar 2001 R Griffiths Meteor Nominees (Meteor Stone Quarry) Feb 1994M BaljeuWestralian Sands (North Yoganup) Mar 1991W GattPoseidon (Karonie mine) Nov 1988JS MeharryHamersley Iron (Dampier) Feb 1988M RaynerCSIRO (Exploration) Apr 1981AJ WoolridgeHill 50 Gold (Mount Magnet) Nov 1981P TsakisirusMt Newman Mining (Nelson Point) Dec 1980M D Hobart Agnew Mining (Leinster)

Department of Consumer and Employment Protection © 2005 Resources Safety 11 Machinery contact with overhead powerlines YearTrucksExcavatorDrillsCranesMisc.Incidents Total

Department of Consumer and Employment Protection © 2005 Resources Safety 12 Review of 628 shocks in last three years Occupation Location Equipment type Circuit function Accident causes

Department of Consumer and Employment Protection © 2005 Resources Safety 13 Electric shocks by occupation

Department of Consumer and Employment Protection © 2005 Resources Safety 14 Electric shocks by location

Department of Consumer and Employment Protection © 2005 Resources Safety 15 Electric shocks by equipment type

Department of Consumer and Employment Protection © 2005 Resources Safety 16 Electric shocks by circuit function

Department of Consumer and Employment Protection © 2005 Resources Safety 17 Electric shock causes

Department of Consumer and Employment Protection © 2005 Resources Safety 18 Electric shocks caused by equipment defects

Department of Consumer and Employment Protection © 2005 Resources Safety 19 Electric shocks caused by work practice

Department of Consumer and Employment Protection © 2005 Resources Safety 20 Opportunities for improvement (many) Regulatory work in progress to: prohibit unnecessary “live” electrical work extend use of RCD “earth-leakage protection” require use of welding VRDs RCD = residual current device VRD = voltage reducing device

Department of Consumer and Employment Protection © 2005 Resources Safety 21 “Live” electrical work Energy Safety introducing new regulations that prohibit unnecessary “live” electrical work undertaken by electricians: excludes maintenance testing no “live” work allowed in domestic premises necessary work must be demonstrated and subject to written work procedures that will assure safety (7% of mining electric shocks involve “live” work)

Department of Consumer and Employment Protection © 2005 Resources Safety 22 RCD - Earth-leakage protection A 30mA RCD will automatically cut off the electricity supply in the event of an electric shock to a person before any harmful effects can occur Only an RCD will detect water ingress into electrical equipment (41% of defects, 25% of shocks) Regulation 5.24 of MSIR 1995 currently requires 30mA RCD protection for all portable apparatus at the mine

Department of Consumer and Employment Protection © 2005 Resources Safety 23 RCD - Earth-leakage protection cont. 18% of shocks involve portable equipment already RCD protected 16% of electric shocks involve lighting circuits that are not currently required to be RCD protected 16% of electric shocks involve control circuits that are not currently required to be RCD protected (potential to protect against 50% of shocks)

Department of Consumer and Employment Protection © 2005 Resources Safety 24 RCD - Earth-leakage protection cont. Proposal: Require all new lighting circuits to be RCD protected, and upgrade existing circuits within 5 years Require all new control circuits to be either extra-low voltage or RCD protected (not practicable to upgrade existing circuits)

Department of Consumer and Employment Protection © 2005 Resources Safety 25 Welding VRDs A VRD will not switch on the electricity supply before a genuine attempt is made to strike an arc, and will automatically cut off the power after welding ceases Welding power will not be established if any person has inadvertently become part of the welding circuit and could receive a shock (welding shocks constitute 37% of work practice failures and 12% of all reported shocks)

Department of Consumer and Employment Protection © 2005 Resources Safety 26 Welding VRDs (voltage reducing devices) Proposal: Require all welding power sources exceeding certain minimum open-circuit voltages be provided with VRD technology within 2 years

Department of Consumer and Employment Protection © 2005 Resources Safety 27 Summary of electric shock incidents Electric shocks are 3rd highest reportable incident There is an electrocution every 2-3 years (the last was in May 2002) Shocks to operators 41%, mechanics 27%, electricians 15%

Department of Consumer and Employment Protection © 2005 Resources Safety 28 Summary of electric shock causes 62% of shocks are due to equipment defects and 34% due to inadequate work practices Major equipment defects: ingress of water 41% exposed “live” parts due to damage 19% Major work practice defects: welding contacts 37% failure to isolate 25% “live” electrical work 21%

Department of Consumer and Employment Protection © 2005 Resources Safety 29 Summary of future regulation Proposed “live” work regulations could eliminate 7% of all shocks Proposed VRD regulations could eliminate 12% of all shocks Proposed RCD regulations could safeguard 50% of the remaining shocks that occur