How does an electric shock occur?
An electric shock occurs when a person comes in contact with an electrical energy source. Physical contact with energised wiring or devices is the most common cause of an electric shock. Like water and metal, the human body is a conductor of electricity and exposure to electrical energy can result in a shock or death (electrocution).
What are the effects from an electric shock?
The effects from an electrical shock will depend on the type of current, how high the voltage was, how the current traveled through the person’s body, their overall health and how quickly the person was treated. While any amount of current over 10 milliamps (0.01 amp) is capable of producing painful to severe shock, currents between 100 and 200 mA (0.1 to 0.2 amp) are lethal.
Even someone with minor injuries or no symptoms at all should be checked by a doctor for internal injuries. Trauma may include burns (the shock can cause a burn where the current enters and leaves the body), muscle pain, contractions, seizures and unconsciousness. The electricity can not only injure blood vessels, nerves, and muscles, but internal organs can also be affected (heart and lungs), resulting in an irregular heartbeat, breathing difficulties and organ failure. You might not see all the damage the shock has caused for up to 10 days after the shock.
Take this example of an electrician who suffered an electric shock whilst working live, putting his life at risk…
An electrician was working on site installing Residual Current Devices (RCD’s) for approximately 20 switchboards. No live work was to occur in relation to these contracted works. The IP (injured person) had received training on company Job Safety Analysis (JSA) and Safe Work Method Statement (SWMS) prior.
The IP had completed a full isolation and installation of the switchboard and had re-energised the switchboard to commence testing the RCD. Prior to testing, the IP noticed part of the duct cover wasn’t fully connected and reached inside the live switchboard to press it back into place. The IP made contact with a live copper component and subsequently received an electric shock to the hand. A call was made to 000 and the IP was taken to hospital for assessment and treatment.
Post incident the switchboard was made safe by a colleague.
The contributing factors which lead to the electric shock was that the IP did not re-isolate the switchboard before placing their hand into the live switchboard.
No live work was to take place, the electrician breached the company’s Live Work Policy, Safe Work Method Statement and pre-start JSA by energising the switchboard and continuing to work within the switchboard.
This example highlights the importance of effective isolation regardless of the duration of the task at hand.
When is it ok to work live?
Other than unavoidable testing and commissioning functions, all electrical work should be carried out on de-energised/isolated installations and equipment.
If you are working live then you are risking your life.
To work live you must have management approval, along with a well documented SWMS, appropriate tools, testing equipment, personal protective equipment and an electrical safety observer must be used when there is no reasonable alternative to performing energised electrical work (live work).
Safety observers must be trained in low voltage switchboard rescue and CPR, they must be hightened to ensure incidents don’t occur in the first place. A safety observer must have a clear understanding of the work being undertaken and the associated risks associated, be in a position to clearly observe the work (one task at a time) and warn of any dangers, and stop any work before the risks become too high or compromises their role as a safety observer.
Safety comes first for all electrical works
Electricians must take reasonable care of their own health and safety, and the health and safety of people who may be affected by their acts or omissions within the work place. Employees must cooperate with their employer and carry out the employer’s actions to comply with their OHS obligations, including JSA and SWMS. The Electricity Safety Law, which is regulated by Energy Safe Victoria (ESV), requires all electrical circuits or electrical equipment handled in the course of electrical work to be disconnected from the electricity supply, unless adequate precautions are taken to prevent electric shock or other injuries. Safe working practices are paramount.
Hints for Electricians to work safely on switchboards
- De-energise and isolate the switchboard or circuit to be worked on
- Test to ensure all parts are de-energised before restarting work
- Ensure a Safe Work Method Statement is developed and adhered to
- Ensure apprentices are adequately supervised
- If the power cannot be turned off, reschedule the work to a time when the power can be isolated
No one should risk their life, or the lives of work mates, for the sake of saving time or inconvenience.