Electricity Generation : First Aid Guidance
"Heartfelt Shock" and First Aid
The human body is basically a water-filled bag with approx. 3 kilohms resistance, making it a pretty good conductor of electricity. Since one side of the mains power supply is grounded, then you can receive fatal electric shocks if your body comes into contact with high voltages - if you're standing on ground the body can complete a circuit and current will flow through you to earth.
The human heart is a muscle which is the most susceptible to stimulation at a frequency of 50Hz. Perversely, this is also the frequency of the UK mains electrical supply. The effects of shock depend on the level of current which flows from a device (and where it flows through the body). Once a certain threshold is reached, you will have no control over the actions of muscles, which means that you may be unable to release your grip on a device and may suffer electrocution.
Below is a summary of the effects of grasping a "live" apparatus or wire.
9mA Probably still able to release the device
16mA Borderline on ability to release the device
20mA Unable to release the device
16-50mA Pain, possible unconsciousness. Heart and respiratory functions probably continue.
> 100mA Heart tremor, asphyxia due to respiratory paralysis. Severe shock and burns. Possible death.
Burns are caused when current passes through the skin tissue, and because of their penetrating action, electric burns can be much deeper than their size might suggest. Extremely serious burns can result from contact with high voltage power lines.
Electric shock First Aid - general guidance
If a person's suspected of receiving an electric shock from the domestic mains supply, you should act quickly and calmly to help the victim, without exposing yourself to the same risk of electrocution.
- If high voltages are involved (HT/ EHT) then it could be dangerous to give first aid. Call for help instead. See Leaps & Volts: Safe Working Distances.
- Avoid touching the victim if he or she may still be in contact with the mains. Switch off and unplug, or use e.g. an insulating dry wooden pole or wooden chair to push the victim clear of the supply.
- If the victim has stopped breathing, you should apply artificial respiration immediately.
- Then treat burns immediately. Relieve pain and reduce tissue damage by cooling the affected area with plenty of clean cold running water. (Using frozen produce, ice etc. is no longer suggested due to the risk of nerve damage.)
- Remove any items of a constrictive nature (rings, watchstraps, bracelets) before swelling starts.
- Apply a sterile dressing for protection from infection. Do not apply lotions, creams or ointments nor prick blisters.
- Seek medical attention.
- Electricity Pylons: an introduction
- Leaps & Volts: Safe Working Distances
- Fuses and Circuit Breakers