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Electrical Isolation

Disconnecting electrical energy sources to make work safe.

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Documents

  • 202631 Mar

    Offshore Inspection Guide Electrical Power Systems

    HSEGuidance

    An inspection guide for assessing electrical power systems and duty holder compliance. It addresses generation, distribution, protection, portable equipment and safe electrical work, with condition-monitoring methods including partial-discharge analysis, thermography and insulating-oil assessment. Performance scoring supports regulatory intervention planning; ATEX equipment is excluded.

  • 20257 Nov

    Smoke in the battery room

    IMCASafety FlashIMCA SF 20/25

    A vessel alongside experienced smoke from overheated nickel-cadmium batteries supplying a DP-system UPS. Crews isolated circuits and removed batteries for cooling, without injury or escalation. The flash examines uncertain causes, restricted cabinet access and incomplete records, highlighting battery inventories, detection, emergency training and installation improvements.

  • 20252 Oct

    Worker suffered eye injuries in electric arc incident

    IMCASafety FlashIMCA SF 18/25

    A vessel electro-technical officer suffered light eye burns from an electrical arc while disconnecting a shore power cable that appeared still energised. Initial findings identified inadequate vessel–quayside communication and documentation. The flash emphasises voltage testing, isolation, improved communication, risk assessments and toolbox talks.

  • 202530 Sep

    BSEE Safety Alert 506 - Arc Flash Incident Highlights Critical Need for Voltage Verification During Offshore Electrical Maintenance

    BSEESafety AlertSafety Alert 506

    An offshore platform cable installation resulted in an arc flash and a minor thermal burn when an electrician used non-insulated pliers inside an energised motor control centre. The alert identifies deficient task analysis and communication, recommending de-energised working where feasible, insulated tools, arc-rated protection, coordinated cable movements and competency assurance.

  • 202518 Jun

    Lock out/Tag out and unauthorised electrical connections/disconnections

    IMCASafety FlashIMCA SF 11/25

    This flash describes missing electrical and mechanical lockouts identified during a vessel engine-room audit, alongside unauthorised electrical disconnections and bypasses. It emphasises suitable lockout devices, documented approval of temporary modifications, restoration checks and clear handovers. Possible links to dynamic positioning trials are presented as assumptions rather than established causes.

  • 202516 May

    Electrical isolation: Failing to “prove dead” at the point of work

    IMCASafety FlashIMCA SF 09/25

    This safety flash examines failures to verify that electrical equipment is dead at the actual work location rather than only at a remote isolation point. Two examples describe personnel accessing live terminals after selecting the wrong thruster or ROV. It emphasises following proving-dead protocols at the point of work.

  • 202529 Apr

    Detergent chemical burn

    IMCASafety FlashIMCA SF 08/25

    An electrician and trainee suffered slight chemical burns from leaked detergent during dishwasher repairs aboard a vessel. Electrical isolation was addressed, but corrosive detergent hazards and labelling were overlooked. The flash highlights secondary hazards, stakeholder involvement, clear hazard identification and appropriate PPE for unidentified liquids.

  • 202416 Jul

    Electric shock after water ingress to switch

    IMCASafety FlashIMCA SF 14/24

    A vessel visitor received an electric shock from a steering-room switch left live and unprotected after maintenance. Water entered during engine-room washing following major repairs. The flash highlights completing maintenance before reinstatement, isolating and protecting electrical connections during cleaning, and recording regular competent inspection and testing.

  • 202314 Dec

    BSEE Safety Alert 478 - Inadequately Maintained Electrical Connections and Compromised Wiring Integrity (6)

    BSEESafety AlertSafety Alert 478

    This alert examines three electrical incidents involving a loose generator cable connection, damaged heat-trace insulation with improper grounding, and rainwater ingress into generator wiring. It recommends that operators consider routine maintenance, training, emergency-response rehearsals, improved cable procedures, lockout/tagout reinforcement and periodic infrared inspections.

  • 20233 May

    Equipment starts unexpectedly

    IMCASafety FlashIMCA SF 11/23

    Three mechanics were maintaining a high-voltage AC unit under lockout/tagout when it restarted unexpectedly. A broken circuit-breaker handle linkage had prevented shutdown. Nobody was injured. The flash highlights verification of de-energisation and correct energy-source isolation, including when equipment is upgraded or modified.

  • 202327 Feb

    Battery explosion during routine maintenance

    IMCASafety FlashIMCA SF 06/23

    A harbour tug’s Chief Engineer sustained minor injuries when a spanner inadvertently short-circuited a battery during preparations to replace a failed disconnect switch. The flash discusses electrical isolation, terminal protection, suitable tools and protective equipment, alongside increased maintenance inspection and consideration of chargers with temperature sensors.

  • 20221 Nov

    Live sub-surface power cable inadvertently cut

    IMCASafety FlashIMCA SF 24/22

    An excavator cut an energised buried power cable during onshore pipeline trenching, without injuries or equipment damage. Incomplete as-built information and misleading drawings left the cable hazard unidentified in risk assessment. The flash highlights isolation, cable tracking during excavation planning and clear communication of stop-work authority.

  • 20221 Apr

    Safety Alert 436 - Arc Flash Injury During Generator Hookup

    BSEESafety AlertBSEE Safety Alert 436

    An electrician sustained a second-degree arm burn while reconnecting a diesel backup generator to a live bus. The alert identifies shortcomings in task hazard analysis, arc-flash protection and lockout documentation, with breaker defects contributing to the incident. It presents measures for operators and contractors to consider, including assessments, qualification checks and breaker condition reviews.

  • 202228 Feb

    Permit to Work and Isolation procedure not followed

    IMCASafety FlashIMCA SF 05/22

    An electrician replacing fuses in a live 930V DC vessel drive cabinet experienced an arc flash without injury. The flash examines absent work permits, unsecured and untagged isolation, inadequate procedures and failure to check isolation before work. Actions focus on reviewing work controls and following workplace instructions.

  • 202116 Nov

    Electric Arc Flash Management

    NOPSEMASafety AlertA711035

    This bulletin examines arc flash hazards and their management on offshore petroleum facilities, drawing on incident notifications and inspection findings. It explains risks during isolation and proving equipment dead, including low-voltage hazards, and discusses engineering measures, procedural controls, training and arc-rated protective equipment alongside operators’ statutory duties.

  • 202122 Sep

    Electrician suffered flash burn to hand

    IMCASafety FlashIMCA SF 26/21

    An electrician suffered a hand flash burn while checking insulation on a 690-volt bus bar aboard a vessel in dry dock. The switchboard became live after an unguarded status switch changed and the power management system closed a breaker. Lessons address isolation, shipyard work permits, supervision and communication.

  • 202130 Jul

    Fault in high voltage equipment

    IMCASafety FlashIMCA SF 21/21

    A vessel’s portable seismic sparker produced sparks at its -5600V terminals during initial testing. Investigation identified incorrect washers and bolt threading that could prevent full tightening. Training time was reduced and reporting delayed four weeks. Recommendations address competence, risk assessments, stopping work, power isolation and prompt investigation.

  • 202117 Mar

    Electric shock due to water in electrical equipment

    IMCASafety FlashIMCA SF 08/21

    During freshwater supply to a vessel, water escaped from a galley sounding pipe and wetted cooking equipment. A steward received a mains electric shock but was unharmed. The flash identifies unassessed spill risks and delayed drainage, and recommends open drainage, revised risk assessments and communication of equipment maintenance requirements.

  • 20212 Feb

    Hand injury when caught in machinery

    IMCASafety FlashIMCA SF 04/21

    A crew member suffered hand and arm fractures during humidifier maintenance when airflow drove an electrically isolated fan and belt. His glove became entangled, drawing his hand and forearm into the machinery. Re-enactment identified an open ventilation outlet condition; the flash calls for procedures to address the previously unrecognised hazard.

  • 202026 Nov

    Cabin fire caused by light fitting overheating

    IMCASafety FlashIMCA SF 32/20

    A minor fire in an unoccupied vessel cabin bathroom followed an internal short or failure in a ceiling light fitting. Its melted plastic cover ignited the toilet lid. The flash recommends cabin and light-fitting inspections, conditional electrical isolation, ready firefighting equipment and safe alarm-raising and response.

  • 202010 Nov

    Two incidents with electrical installations with potential for a fire

    IMCASafety FlashIMCA SF 31/20

    Two electrical incidents concern fat-contaminated galley sockets causing an earth fault and potential fire, and a minor machinery-space fire associated with lost terminal continuity. The flash describes socket isolation, lockout and cleaning, dry chemical powder extinguishing, and routine checks of electrical connections and terminations during planned maintenance.

  • 202025 Aug

    Electrical shock from containerised portable office

    IMCASafety FlashIMCA SF 25/20

    An employee received a mild electric shock while tidying a containerised office, touching live wiring hidden beneath a desk. The cable remained after equipment removal during storage. The flash identifies missed checks and absent electrical verification, and describes isolation, inspection and formal instructions for container fit-out and modification.

  • 202019 Feb

    Electric shock resulting in burn

    IMCASafety FlashIMCA SF 06/20

    An ROV technician sustained an arm burn from electric shock while bleeding a hydraulic filter in a technical workshop. A cut cable routed through a water drain remained live from a separate transformer despite local lockout. The flash recommends proper cable disconnection, documented modifications, formal change management and supervisor handover.

  • 201912 Aug

    Seawater entering cabin caused electrical fault

    IMCASafety FlashIMCA SF 19/19

    A passenger cabin porthole left slightly open during vessel operations admitted seawater into an electrical socket, causing a short circuit, burnt wiring and smoke. Responders isolated the supply. The flash highlights vessel induction, watertight integrity inspections when leaving port and a safety discussion involving passengers and crew.

  • 201724 Oct

    Potential for fatalities from electrical incidents

    NOPSEMASafety AlertA572494

    This alert reviews three electrical dangerous occurrences notified within less than 90 days, with no injuries or cardiac irregularities reported. It identifies failures in cable identification, isolation confirmation, proving dead, permits, task analysis, procedures and competence, and sets out requirements for safe electrical work.

  • 201721 Mar

    Near miss: Fire hazard from engine room equipment failure

    IMCASafety FlashIMCA SF 06/17

    During planned maintenance in port, a vessel’s lube oil pre-heater overheated and produced smoke without fire. A safety cut-off switch had failed in the reset position. The flash describes electrical and mechanical isolation, confusion over an impending drill, defective emergency communications and actions addressing similar systems and emergency procedures.

  • 20166 Dec

    First aid injury: Electric shock

    IMCASafety FlashIMCA SF 33/16

    An ROV supervisor contacted a conductor in the wrong transformer cabinet during fault finding, suffering an electric shock and hand burn. The alternate system received 40V DC despite its breakers being off and potentially held high-voltage capacitive energy. Lessons address isolation, cabinet access, system familiarisation and testing before touch.

  • 20163 Oct

    High potential near-miss incident: 440v cable damaged by grinder

    IMCASafety FlashIMCA SF 25/16

    During vessel mobilisation, a rigger/welder damaged a live 440 V cable while grinding aluminium protection covers in place over cables on the aft deck. The investigation identified inadequate task planning, permit coverage, risk assessment and toolbox communication, with no electrical isolation during work and delayed isolation afterwards.

  • 20152 Oct

    Electrical shock – Failure of isolations and barriers

    IMCASafety FlashIMCA SF 14/15

    A crew member received an electrical shock while stripping insulation during replacement motor work. The isolation omitted a space-heater supply in the test position, and a generic motor drawing had been used. The flash stresses equipment-specific drawings in permit-to-work and lockout/tagout procedures when determining isolation.

  • 2015Oct

    The Electricity at Work Regulations 1989

    HSEGuidanceHSR25

    Technical and legal guidance accompanies the Electricity at Work Regulations, explaining duties and precautions across operational voltages. It addresses electrical shock, arcing and explosion hazards, equipment suitability, maintenance and competence. Detailed discussion distinguishes switching off from isolation, explains proving dead and considers justification and precautions for live work.

  • 201523 Jun

    MSF: Vessel electrical equipment caught fire

    IMCASafety FlashIMCA SF 09/15

    This safety flash describes a vessel fire caused by failure of a deck floodlight capacitor in an electrical ballast unit. The fire detection system activated, the ship’s fire party assembled, and the circuit was isolated. Replacement of the unit followed, with minimal damage reported.

  • 201520 Mar

    Electric shock incident

    IMCASafety FlashIMCA SF 04/15

    An electrician received a 220V AC shock while working on a 24V remote input/output module in joystick electrical equipment, sustaining minor left-hand burns. The flash describes the current path through an anti-static earth strap, inadequate personal risk assessment and the need to verify isolation using a voltage tester and compatible proving unit.

  • 20134 Apr

    Near-miss: Exposed live electrical cable

    IMCASafety FlashIMCA SF 05/13

    A crewman found an exposed live lighting cable sparking against a vessel bulkhead after dry docking. A contractor had removed the flood lamp outside the agreed scope without permits or electrical isolation. Findings highlighted inadequate planning, supervision and communication, and failure to follow management-of-change procedures.

  • 201225 Jun

    Near-miss: Live electrical cable

    IMCASafety FlashIMCA SF 06/12

    During contractor equipment demobilisation aboard a vessel, removal of lockout/tagout re-energised a disconnected cable at 440 volts. Its ends touched the chassis and arced near an employee’s hand; nobody was injured. The flash identifies communication, permit, isolation verification, multiple-key lockout, breaker labelling and electrical drawing deficiencies.

  • 20124 Apr

    Near-miss: 220v cable not isolated during work

    IMCASafety FlashIMCA SF 03/12

    A vessel maintenance near-miss left exposed 220 V wiring after a light fitting was disconnected following incorrect multimeter testing. The flash discusses isolation checks and consultation failures, notes further fleet incidents, and sets out actions concerning authorised isolation, dedicated voltage indicators and tester checks before and after proving dead.

  • 201127 Jul

    Electrician received electric shock

    IMCASafety FlashIMCA SF 08/11

    A vessel electrician received an electric shock while investigating a faulty running machine supplied through a 220v/110v transformer. A cable with two male connections exposed live pins during disconnection. No injuries were identified. The flash highlights isolation before testing, equipment inspection and risk assessment before installation and use.

  • 2010Mar

    The safe isolation of plant and equipment

    HSEGuidanceHSG253

    HSE guidance explains how to select, install, prove and maintain process isolations for intrusive work, then reinstate plant safely. It combines baseline selection with risk assessment, valve and pipework design, work authorisation and isolation security. Appendices address specialist methods, pipelines, purging and instrument isolation, supported by incident examples.

  • 20092 Jun

    Electric shock near-miss

    IMCASafety FlashIMCA SF 07/09

    An ROV technician received an electric shock while rerouting a tether, without injury. Energising the tether management system produced induced voltage in isolated conductors, while two earthing clips had become dislodged. The flash examines insecure earthing connections and recommends design improvements, high-voltage training and warning signage.

  • 2009Apr

    MAIB Safety Digest 1/2009

    MAIBDigestSD 1/2009

    A collection of merchant-vessel, fishing and small-craft accident lessons examines fires, groundings, collisions, flooding and injuries. Cases address bridge teamwork, fatigue, evacuation-system defects, chemical spill response and electrical isolation. Preventive lessons emphasise equipment maintenance, navigational competence, work permits and timely communication with emergency services.

  • 20089 Oct

    Risk of electrocution during routine work

    IMCASafety FlashIMCA SF 15/08

    A technician aboard a dive support vessel received a slight electric shock while dismantling a plug to reroute a live 440 V three-phase winch cable through a sea-fastening mousehole. No injuries were reported. The investigation identified missing work permits, isolation, risk assessment and toolbox discussion, alongside inadequate induction and supervision.

  • 200712 Mar

    Galley equipment broke free of fastenings during severe weather

    IMCASafety FlashIMCA SF 02/07

    A vessel’s galley grill fryer toppled during a severe storm, narrowly missing a steward without injury. Investigation found securing bolts attached only to tiles rather than the steel deck. The flash describes evacuation, electrical isolation, temporary sea-fastening, checks of other appliances and secure reinstallation after the weather abated.

  • 20061 Jul

    Poor Quality Light Fixture Causes Fire

    IADCSafety AlertIADC Alert 06-25

    An alert describes a night-time fire in an unoccupied rig camp cabin, attributed in the title to a poor-quality light fixture. After smoke was spotted, the cabin’s electricity was isolated and a portable dry powder extinguisher used. Ceiling material was removed to check for smouldering in the roof void.

  • 20041 Jun

    Fire in switchboard room

    IMCASafety FlashIMCA SF 05/04

    This flash describes a fire in a vessel’s carousel switchboard room during permitted hot work. Initial firefighting encountered difficulties locating extinguishers and raising the alarm. Fire parties extinguished the blaze using water and breathing apparatus. Lessons address permit inspections and auditing, fire-hose connection keys, lighting and fire-party communications.

  • 20031 Feb

    Injury involving contact with a vehicle battery

    IMCASafety FlashIMCA SF 02/03

    A safety flash describes a circumferential ring-finger burn during disconnection of a 12-volt vehicle battery. A crescent wrench slipped, contacted metal and grounded out; the worker’s gold ring contacted the wrench. The flash highlights battery burn hazards and recommends removing jewellery before work near batteries or connected equipment.

  • Undated

    UPS Capacitor Failure and Power Loss at Perdido Spar

    BSEEInvestigation Report

    Investigates a reported fire and power loss at Perdido Spar following UPS capacitor failure. Smoke detection triggered automatic shut-in and personnel mustered; the fire team saw no fire. Electrical troubleshooting identified inverter arcing before lockout and bypass. The report recommends replacing fans and capacitors on similar units.

  • Undated

    Arc Flash During Vapour Recovery Unit Cable Replacement

    BSEEInvestigation Report

    An investigation examines an arc flash during vapour recovery unit cable replacement on Pompano platform. A bandsaw cut the wrong, energised cable, causing equipment damage but no injuries or pollution. Findings address incorrect cable identification, missing verification, incomplete task hazard analysis and failures to provide and follow cable demolition procedures.

  • Undated

    Crane Boom Fell During Boom Motor Seal Replacement

    BSEEInvestigation Report

    Investigation of a crane boom falling during boom motor seal replacement on a mobile offshore drilling unit. Removing the integrated motor and brake left the boom unsupported; it struck a liquid nitrogen tank without rupturing it. Recommendations address manufacturer instructions, boom support, load removal and subsequent electrical isolation.

  • Undated

    Heat-Tracing Fire on Offshore Platform

    BSEEInvestigation Report

    An investigation records a heat-tracing fire at the Bullwinkle platform. Damage or wear to the element was identified as the probable cause. A high-impedance arcing fault did not trip the breaker, and flames repeatedly returned after extinguishing. Electrical isolation stopped reignition; all personnel were accounted for during muster.

  • Undated

    Variable Frequency Device Failure Releases Smoke and Prompts Muster

    BSEEInvestigation Report

    BSEE investigates a variable frequency device failure at Perdido Spar that released smoke, triggered automatic shut-in and prompted personnel muster. The report attributes the event to a B-phase reactor failure to ground, describes electrical isolation and fire watch, and calls for investigation of the reactor thermal switch’s failure to trip.

  • Undated

    Arc-Flash Injury During Platform Wiring Replacement

    BSEEInvestigation Report

    An investigation describes an arc-flash injury during wiring replacement on the Hillhouse platform. Re-energisation from shore made wires live while a worker prepared them for splicing. Findings identify missing isolation permits, an incomplete job hazard analysis, failures to confirm personnel clearance, reliance on drawings and non-compliance with lockout procedures.

  • Undated

    Roll Up! Electrical Safety in Construction

    OSHAGuidanceOSHA 4496

    This construction toolbox talk addresses electrical hazards affecting electricians and other workers. It outlines qualified-worker requirements, feasible de-energisation, lockout/tagout and voltage checks. Guidance also covers insulated tools, protective equipment, GFCI testing, cord inspection and selection, avoiding overloads and wet conditions, and maintaining clearance from overhead power lines.