DGS/SEETerritorial Safety Officer (TSO) - Initial Territorial Safety Officer (TSO) Initial course SPECIFIC HAZARDS ELECTRICITY EDMS No DGS/SEETerritorial Safety Officer (TSO) - Initial Objectives of the session Awareness of electrical dangers Prevention of electrical hazards Your role as TSO People or services to be contacted SPECIFIC HAZARDS - ELECTRICITY EDMS No DGS/SEETerritorial Safety Officer (TSO) - Initial 1. Introduction 2. Electrical hazards: description and consequences 3. Electricity regulations at CERN 4. Protection against electrical hazards 5. Electrical accidents 6. The role of the TSO 7. Conclusion SPECIFIC HAZARDS - ELECTRICITY EDMS No DGS/SEETerritorial Safety Officer (TSO) - Initial Electrical accidents in the last years Number of electrical accidents since 1975 Introduction EDMS No DGS/SEETerritorial Safety Officer (TSO) - Initial Severity of electrical accidents (France 2011) Introduction Accident resulting in absence from work Accident resulting in permanent disability Accident resulting in death Electrical hazardsAll occupational accidents Source INRS (France) 2011 EDMS No DGS/SEETerritorial Safety Officer (TSO) - Initial 1.Electrical Shock 2.Arc Flash Electrical Hazards EDMS No DGS/SEETerritorial Safety Officer (TSO) - Initial 1.Human injuries (death) 2.Blast 3.Fire 4.Power outage 5.Installation damaged 6.Physics stopped Consequences EDMS No DGS/SEETerritorial Safety Officer (TSO) - Initial It is an electric current passing through the human body independently from the voltage level Severity of the shock depends on: Current frequency Intensity value (dangerous from 5 mA) Duration time Contact surface Pathway Skin state (dry, humid) Soil nature Low voltage does not mean low hazard Electrical shock EDMS No DGS/SEETerritorial Safety Officer (TSO) - Initial I=V/R The human body has an electrical impedance of around 1000 Ohms for a contact voltage of 230 V. Numerous factors affect this impedance as mentioned Low voltage socket 230V / 1000 = 230 mA Ohms Law: Electrical shock EDMS No DGS/SEETerritorial Safety Officer (TSO) - Initial Ventricular fibrillation (1s) Hazard thresholds in AC Cardiac arrest Respiratory muscles paralysis Muscle contraction threshold Perception Inhibition of the nerve centres 1A 50 mA 30 mA 10 mA 0,5 mA 2A Effects of the current on human body Electrical shock Electrocution Electrocution is an electrical shock resulting in death EDMS No DGS/SEETerritorial Safety Officer (TSO) - Initial Injuries locations distribution Lower limbs and feetInternal Other Hands Upper limbs Head Eyes Trunk Electrical shock EDMS No DGS/SEETerritorial Safety Officer (TSO) - Initial Short circuit a) Melting of metal b) Very loud noise 140 dB(A) c) Stifling pressure waves d) Extreme heat of up to 10,000 o C e) Scattering of debris and gases f) UV rays Flash arc EDMS No DGS/SEETerritorial Safety Officer (TSO) - Initial - Regulations applicable to electrical installations (IS24) - Emergency stops (IS5) - Safety Inspections (IS4) - Selection of electrical cables (IS23) Electricity regulations at CERN Equipment - EU directives (CE marking) - Applicable IEC Installation CERN Code C1 EDMS No DGS/SEETerritorial Safety Officer (TSO) - Initial CERN has procedures for electrical interventions. CERN uses the NFC Electricity regulations at CERN Operation Any electrical work under voltage is PROHIBITED at CERN Other rules visit the HSE Units website: Other rules visit the HSE Units website: https://espace.cern.ch/hse-unit/https://espace.cern.ch/hse-unit/ EDMS No DGS/SEETerritorial Safety Officer (TSO) - Initial Overcurrent -Circuit breakers -Fuses -Differential Electrical Hazards Protection Direct contacts -Clearance distance -Clearance distance from live conductors (depends on voltage level) -Enclosures -Enclosures: IP2X (or higher) for LV and IP3X (or higher) for HV -Insulation -Insulation protecting live conductor -ELV -ELV (extra low voltage) preferred -Wearing PPEs -Wearing PPEs (to be maintained and checked) Indirect contacts -Earthing -Earthing conductive parts (metallic enclosures, cable trays, pipes, etc ) -Reinforced insulation -Reinforced insulation class II equipment (EN 61140) EDMS No DGS/SEETerritorial Safety Officer (TSO) - Initial Emergency Stop Buttons In addition at CERN (IS-5), Emergency Stop Buttons are available and accessible: (AUG) 1.General Emergency Stop (AUG) (AUL) 2.Local emergency stop (AUL) 3.Equipment emergency stop Electrical Hazards Protection EDMS No DGS/SEETerritorial Safety Officer (TSO) - Initial Typical Electrical Accidents EDMS No DGS/SEETerritorial Safety Officer (TSO) - Initial Example 1 Buried cables accidentally cut AOC, VIC, always useful CERN Electrical Accidents EDMS No DGS/SEETerritorial Safety Officer (TSO) - Initial Example 2 Electrical fire Triggered remotely following malfunctions. Transformer = energy + fuel CERN Electrical Accidents EDMS No DGS/SEETerritorial Safety Officer (TSO) - Initial Example 3 Electrical fire in a kitchen The damage was limited thanks to a member of the housekeeping staff who acted quickly using a fire extinguisher. CERN Electrical Accidents EDMS No DGS/SEETerritorial Safety Officer (TSO) - Initial Example 4 - Electrical fire in a capacitor rack The TSO must be informed about installations for which particular precautions are required. CERN Electrical Accidents EDMS No DGS/SEETerritorial Safety Officer (TSO) - Initial Fires: PS Magnet, BA3, BB3, OMEGA, NA23, NA48, ME10, CTF3 Explosions: BE, 867, BA5 Electrical shocks: Some people seriously injured in CERN installations CERN Electrical Accidents EDMS No DGS/SEETerritorial Safety Officer (TSO) - Initial In the event of imminent danger: it is your right and your duty to take action TSO role EDMS No DGS/SEETerritorial Safety Officer (TSO) - Initial What to do: P.A.R. (Protect, Alert, Rescue) TSO role EDMS No DGS/SEETerritorial Safety Officer (TSO) - Initial The TSO ensures: 1.Electrical inspections are performed and unconformities remedied by the installation owner 2.Awareness of the electrical installations in his building 3.Safety observance during temporary cables and electrical works 4.Tests of local emergency stops periodically TSO role EDMS No DGS/SEETerritorial Safety Officer (TSO) - Initial If in doubt, please ask the electrical responsible in the relevant groups EN-EL, BE-RF, TE-ABT, TE-EPC, GS-SE or Contact electrical experts in HSE Unit (SEE) Christian BERNARD Jose GASCON TSO role EDMS No DGS/SEETerritorial Safety Officer (TSO) - Initial Most fires at CERN are generated by an electrical hazard Electrical accidents are rare but can be severe Conclusion EDMS No