THE EFFECT OF ELECTRICITY ON THE HUMAN BODY
The effect that an electric shock has on your body depends on the path that the current flows through your body. This is because the body components such as your skin, fatty tissues, muscles and bones have different resistance's that vary with external influences, such as if your skin is wet or dry as wet skin has a lower resistance than dry skin, the amount of contact surface area and the contact pressure. The duration of the shock and the frequency of the voltage also determine the effect that the shock has on your body. The extent of the electric shock can vary from a tingling sensation to muscular contraction causing respiratory paralysis, ventricular fibrillation and the danger of severe internal and surface bums if not death. The effect will vary from individual to individual due to each person's unique physiology.
The resistance of the skin can vary considerably for voltages below 50 volts and usually restricts the current to relatively safe levels. This is why electrical regulatory bodies such as The Office Of Energy in Western Australia classify Extra Low Voltage as 0 to 50 volts and do not require an electrical license when working on equipment operating up to 50 volts. The skin's resistance can decrease rapidly for voltages above 50 volts and the current flow through vital organs such as the heart is often life threatening, which is why an electrical license is usually required when working on equipment operating above 50 volts. The Office Of The Energy in Western Australia classify Low Voltage as 50 volts to 1000 volts and regulations require a Restricted Electrical License, an Electrical License or an Electrical Contractors License to work on equipment that operates with these voltage levels.
Involuntary muscular contraction can occur at low levels of current and can lead to physical actions such as falling off ladders which will then lead to more serious physical injuries. One of the problems with electrocution is the failure for the victim to let go of the conductor or appliance because of muscular contraction, a factor that the rescuer must be always remember.
The main cause of death from electric shock is ventricular fibrillation which is a condition of the heart in which bundles of muscles respond erratically caused by incorrect muscle timing, so consequently no blood is pumped, resulting in oxygen starvation to the brain which leads to death. Once ventricular fabrication is established it is extremely unlikely the normal operation of the heart will resume by its self
This is why ambulance officers use a device called a defibrillator. Because the heart is made up from a lot of bunches of muscles, if a large DC voltage is applied directly to the body via the defibrillator's pads, the muscles can be made to squeeze together for a period of time then released. The heart muscles are momentarily exhausted for a while, until hopefully the heart will attempt to resume its normal rate.If fibrillation reoccurs again the procedure may have to be repeated.
All electric shocks have to be reported to The Office Of Energy on 1800 678 198 so that they can investigate the cause of the shock and change work practices, regulations etc to try and ensure that it can be prevented from occurring again. All employers have to report electrical shocks, accidents and potential accidents to The Office Of Energy to ensure work standards are safe.
It is absolutely imperative to seek medical attention after receiving a severe shock because internal parts that may have been burnt may release poisonous toxins after a few days which may kill the person even if they seen healthy.
A first aid certificate would be usefull if you found a person lying on the floor unconscious from electrocution who was still touching the active appliance, as you would know how to assess and remove the danger, check for a response, clear the airway and check for breathing, check for circulation, carry out Expired Air Rescuscitation and Cardio-Pulmonary rescuscitation if required and call for help.
AS 3859-1991 Effects of current passing through the human body.
|50 Hz AC current||Effect on human body (typical)|
|0.5 - 2 mA||Threshold of perception|
|2 - 16 mA||muscular contraction, experience pain|
|16 - 30 mA||Respiratory paralysis|
|50 mA - 200 mA||Ventricular fibrilation|
|200 mA --->||Burns to tissue and organs|
|1 amp is 1000 mA|