3.1 Electrical Safety

Candidates must be able to work safely and prevent accidents in the labratory, workshop or home. Candidates must know what to do if an accident happens.

  • Created by: Aiswani_S
  • Created on: 28-07-14 17:46

3.1.1 Dangers of Electricity

What effects on the human body occur when in contact with an electric current

  • Electric shock is defined as a sudden violent response to electic current flow through any part of a person's body. 
  • Electrocution is death caused by electric shock.
  • Primary electrical injury is tissue damage produced directly by electrical current or voltage.
  • Deep tissue injuries
  • High coltage injuries can cause an electric burn
  • Dead skin cells on the skin can help resist the voltage however beneath that is wet, relatively salty tissues that can conduct electricity very well.
  • Many extra things can contribute to how serious the injury turns out- the voltage, current as well as what the body is doing (holding metal objects, immersed in water, deep cuts etc.)
  • Electricty tries to reach the ground and so the whole body takes part in allowing the electrons to pass through!
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3.1.2 First Aid

  • Check for person's response and breathing. It may ne necessary to commence cadiopulmonary resuscitation (CPR)
  • Call 999, use resuscitation techniques so you can increase the person's chance of survival until the ambulance arrives (this information can be given by the ambulance call-taker).
  • If their breathing is steady and they are responsive, attend to their injuries. Cool the burns with cool running water for 20 minutes and cover with dressing. Cling Film wrapped around the burns can be used to cover burns, not tightly. Never put ointments or oils on burns. If the person has fallen from a height, try not to move them unnecessarily in case they have spinal injuries. Only move them if there is a chance of further danger from the environment (such as falling objects).
  • Talk calmly and reassuringly to the person, do not look scared and do everything appropriatly.
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3.1.3 Prevention of accidents with electricity

  • Everyone should be supervised so that in case of an emergency there is someone to help; everyone should also know how to summon help in an emergency to increase the victim's chance of survival. An amulance can come and help the one that needs aid as well as treat/heal them.
  • Causes: faulty appliances, damaged or frayed cords or extension leads
  • electrical aplliances coming in contact with water; incorrect or deteriorated household wiring; downed powerlines; lightning srike.
  • Portable Appliances can have damages to it making it unsafe to use. There are many tests such as Polarity checks or Insulation resistance. These are important to check as it affects the flow of electricity and this can lead to electric shocks etc. for the user. e.g. insulation resistence checks if the cords are covered properly; polarity checks that the live and neutral of the plug are connected to the correct terminals.
  • A component becomes hot because it is dissipating energy as heat. This is mainly caused by internal resistance and often over current.
  • Capacitors do not discharge very quicklyif they hold a lethal charge, unless they are discharged manually. This is dangerous because you can get electrocuted even if the equipment is isolated and so is very dangerous to handel.
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3.1.4 Electrical safety devices

  • Circuit Breakers- an automatic device for stopping the flow of current in an electric as a safety measure
  • - A fuse operates once and then must be replaced but circuit breakers can be reset; thermal magnetic circuit breakers sense the overheating from overcurrent and stop the flow of current to prevent accidents; magnetic uses a solenoid where the pulling force increases as the current increases, as the solenoid increases beyong the rating of a circuit breaker contacts solenoid's pull releases the latch and this stops the current flow.
  • Divide the Wattage by the voltage to determine current in amps; Multiply amps by 1.25 (National Electrical Code requires protection at 125%); Install circuit breakers with atleast that value, if not exactly right then the next standard size up.
  • A safe low voltage from th mains supply can be obtained by using a transformer


(how a three pin plug is wired) Blue - neutral, brown - live, green and yellow - Earth

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