BEAMLINE for SCHOOLS
ELECTRICAL HAZARDS
SAFETY
15th September 2016
HSE Unit
1
Introduction - Basics
• Conductors – substances, such as metals-little resistance to electricity
• Insulators – substances, such as wood, rubber, glass, and bakelite-high
resistance to electricity
• Current – movement of electrical charge
• Resistance – opposition to current flow
• Voltage – a measure of electrical force
• Earthing – a conductive connection to the earth which acts as a
protective measure
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Introduction - Hazards
• There are four main types of electrical hazards:
1.
2.
3.
4.
Electrocution (death due to electrical shock)
Electrical shock
Electrical burns
Falls
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Electrical Shock
• Current passes through the body
• Severity of the shock depends on:
o Path of current through the body
o Amount of current flowing through the body
o Length of Time current flows through the body
Low voltage does not mean low hazard!!!
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Effects of current on human body
2A
1A
50mA
30mA
Death almost certain: brain, heart
stopped, organs badly burnt…
Stopping the heart beating properly
Permanent ventricular fibrillation
Respiratory muscles can become paralysed
10mA
Muscles contract causing you to freeze
0,5mA
Slight tingling sensation
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Electrical Shock Injuries
• Electrical burns
• Thermal contact burns
• Related arc / flashover hazards:
–
–
–
–
–
–
Strong blast and high pressure wave
Blow melted metal and vapors
High temperature (10 000ºC)
UV ionization
Flammable gases or combustible dusts
Fire and smoke
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How protect against electrical hazards?
• Using compliant electrical equipment (IEC standards, EU directives)
• Electrical networks sized according rules (https://espace.cern.ch/hse-unit/ )
• Protective devices to avoid electrical faults



Breakers
Residual current devices
Fuses
• CERN Emergency buttons
But not enough!!!
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Protect yourself from electricity
• Wear Personal Protection
Equipment “PPE”
• Turn power off before touching electrical equipment
• Too many items plugged into a
socket overheat and cause a fire.
• Don’t use defective equipment
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In case of electrical accident
1. If possible, disconnect the electrical supply using AUG
2. Call fire brigade at 74444 or use red phones
3. Take precautions to protect yourself and anyone else in
the vicinity
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OBEY ALL SIGNS AND BARRIERS!
Signs, Symbols, Tags, and Barricades
are used to warn personnel of potential
electrical hazards.
HIGH
VOLTAGE
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BEAMLINE for SCHOOLS – East Area
THANK YOU FOR
YOUR ATTENTION
15th September 2016
HSE Unit
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