ELECTRICAL SAFETY

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ELECTRICAL SAFETY
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Introduction

• Everyone should have some knowledge of the every
  day source of energy known as electricity
• Everyone should also know about the potential
  hazards how to avoid them

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Effects Of Electricity

• Many people have received an electric shock at
  some stage or other through carelessness
• Main effects
• Neuromuscular (stimulation of nerves muscles)
• Heating (burns)
• Electrolysis (decomposition/chemical change)
• Heart (50 microamps can interfere with cardiac
  cycle)

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Cautions

• It is necessary to respect electricity its
  hazards
• It would appear that the young old are more
  prone to electric shock
• Perhaps this is due in the first instance due to
  a lack of appreciation of the dangers
• And in the second instance due to over familiarity

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Cautions

• Electrocution claims the lives of a few hundred
  people each year, mostly involving domestic
  electrical equipment

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Hospital Safety

• Electrical equipment is used in Hospitals
  therefore the same risks are present, but the
  hazards are greater due to the involvement of
  sick people

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Hospital Safety

• Now days the patient environment contains a large
  amount of medical equipment providing various
  functions to aid the care of patients
• Many items of medical equipment may be connected
  to the patient at the same time

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Hospital Safety

• Human susceptibility to electric shock varies
  from individual to to individual depends on a
  number of factors
• The patients general state of health
• The position of any electrodes on the patient
• The dampness of the patients skin

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Safety Standards

• Modern medical equipment is now manufactured in
  such a way that the risks of electric shock are
  minimal

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Safety Standards

• Equipment is designed built to comply with
  safety standards, namely BS EN 60601-1
• This lays down constructional guidelines for
  medical equipment which influence the safety of
  the equipment

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Safety Testing To BS EN 60601-1

• Medical electrical equipment is divided into two
  classes
• Class 1
• Class 2
• And, three types
• Type B
• Type BF
• Type CF

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Class 1

• Is equipment in which protection against electric
  shock does not rely on basic insulation only, but
  which includes an additional safety precaution,
  in that means are provided for the connection of
  the equipment to the protective earth conductor
  in the fixed wiring installation in such a way
  that accessible metal parts cannot become live in
  the event of a failure of the basic insulation

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Class 2

• Is equipment in which protection against electric
  shock does not rely on basic insulation only, but
  in which additional safety precautions such as
  double insulation or reinforced insulation are
  provided, there being no provision for protective
  earthing or reliance on installation conditions

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Type B

• Is equipment providing a particular degree of
  protection against electric shock, particularly
  regarding
• Allowable leakage current
• Reliability of the protective earth connection if
  present

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Type BF

• Is type B equipment with an F type applied part
  (applied part isolated from all other parts of
  the equipment to such a degree that the patient
  leakage current allowable in single fault
  condition is not exceeded when a voltage equal to
  1.1 times the highest rated mains voltage is
  applied between the applied part earth)

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Type CF

• Is equipment providing a degree of protection
  higher than that for type BF equipment against
  electric shock particularly regarding allowable
  leakage currents, having a F type applied part

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Symbols on Medical Devices

• Class II equipment
• Type B equipment
• Type BF equipment
• Type CF equipment

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Symbols on Medical Devices

• Protective Earth
• Earth (ground)
• Equipotentiality
• Attention, consult accompanying documents
• Dangerous voltage

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Safety Testing Regime

• BS EN 60601-1 is a constructional standard
• Electricity At Work Regulations 1989 give some
  guidance
• Medical equipment needs to be safety tested
  annually to provide some degree of assurance
• Once tested, equipment has a safety test label
  attached that indicates a retest date

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Common Safety Test Problems

• Most problems appear on the mains part
  (particularly detachable mains leads)
• Extra vigilance is therefore required by users

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Photos

• Can you spot the problems?

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Examples

• Can you spot the problems?

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Fuses/Circuit Breakers

• Prevent overloading fires
• Stop the electrical current if it exceeds a safe
  value
• Fuse rating
• Power V I
• transposing, IP/V

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Fuse Examples

• What fuse should be fitted in the plug for the
  following
• 1150 Watt toaster
• 1600 Watt hairdryer
• 150 Watt patient humidifier
• 20 Watt patient monitor

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Hazards

• Water electricity
• Overloaded circuits
• Damaged insulation
• Misuse of extension cables
• Exposed wiring
• Power cords in walkways

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Precautions

• If equipment gets wet, get it checked
• If cabling damaged/exposed, get it checked
• Do not replace fuses on medical equipment
• If equipment damaged, get it checked

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How Can Users Assist?

• Do NOT carry out any repairs yourself
• Check equipment for damage before use
• Ensure there is no damage to mains plug
• Ensure there is no damage to mains cable
• Do understand how to use the equipment safely

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Points To Remember

• Fuses are the weakest link
• Avoid touching patients equipment at the same
  time, as a conductive path exists
• Let common sense prevail

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Safety First

• Remember do not end up like this person!