“Everyone was gathered in the unfinished Luna Park, waiting with baited breath to see the power of this new substance they call ‘electricity’. Mr Edison, a well known businessman and inventor, was going to show that even a mighty pachyderm could be reduced to nothingness by the sheer strength of this so called alternating current.”
It is quite possible that similar words found their way in the diaries of those spectators present in 1903 at Edison’s demonstration on how dangerous AC was - as opposed to the DC he himself hoped to promote. The history is hazy about the details of Edison’s demonstrations and the death of the elephant, but it is safe to say that in the last century we have learned so much more about electricity and how to keep users safe.
Today we acknowledge that electricity can be a real hazard to many employees at their workplace because it acts as a “silent killer”. Electricity cannot be seen, heard or smelled. Its presence or absence is felt only when the TV set refuses to turn on or the electronic clock no longer wakes us up on time for work.
Electrical engineers and technicians will agree that improper use and irresponsible human behavior is the number one cause of electrical shock, which can result in electrocution, serious burns or other injuries and even death.
Statistics show that there are several hundred electrocutions each year, all of which could have been prevented with education and proper testing of electrical equipment. Therefore, a basic understanding of the shock hazard along with the physiological effects on the human body is vital for electrical safety.
Electrical shock occurs when a person’s body completes the current path of an electrical circuit. Shocks can appear in their mildest form as a slight tingle or as immediate cardiac arrest at their most dangerous.
The severity of electrocution depends on factors such as individual’s resistance, voltage, current path and duration of contact. Therefore, touching a poorly insulated string of Christmas lights may lead to no more than a mild stinging sensation, whereas high voltage wires can char a human being in seconds.
There have been many studies performed in this area and the following chart illustrates average values of current and the effects it can have on a normal healthy human:
1 mA Barely perceptible
1-3 mA Perception threshold (most cases)
3-9 mA Painful sensations
9-25 mA Muscular contractions (can’t let go)
25-60 mA Respiratory paralysis (may be fatal)
60 mA or more Ventricular fibrillation (probably fatal)
4 A or more Heart paralysis (fatal)
5 A or more Tissue burning (fatal if vital organ)
Although the majority of electrocutions are the result of ventricular fibrillation, burns such as electrical burns, arc burns and thermal contact burns are the most common shock-related injury.
Electrical burns are among the most serious of injuries and require immediate medical attention. They occur when electric current flows through tissues or bone, generating heat that causes tissue damage. This occurs because the body cannot dissipate the heat generated by current flowing through the resistance of the tissue and it destroys it through its high temperatures.
Most electrical accidents result from usage of unsafe equipment or installations, but also because of improper use of electrical devices and plugs.
The moral here, similar to that of Edison’s elephant experiment, is that irrespective of one’s size and robustness, electrocution can have dire consequences and can even be fatal. So knowing how current works and how to keep safe can go a very long way for employees, making the difference between life and death.