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An illustration of how an electric or electronic product could pose a potential electric shock
The conductive chassis of these products are so soft that with your bare hands you can bend after applying some force , or create a dent or curve with a small object .
prepared on 1 June 2009
Click on this sentence to see also in photographic illustration page on a DVD recorder purchased iin the Canadian Market with UL cerification
Most of the audio and video processing equipment in the North American market implement two-prong ac plug equipment , instead of three-prong .
In spite of three prong plugs are the ones that help guard against electric shock .Three-prong equipment have the third rod ,which is connected to the ground from the circuit breaker is also bound to the conductive enclosing cabinet of the product ,or to the exposed metal conductors for protection against electric shock .
This will detect and shut off the AC power if there was any defects inside the faulty product (see the first diagram below).
(see both following diagrams below,both zoom enabled when clicked on them , and see the red arrow touching the deformed panels inside the unit illustrating short between the metal chassis and the live terminal )
The most prominent reason for not implementing three-prong method is because the ground terminal on the three-prong gives a path for the infamous 60 hertz noise to penetrate into the equipment's circuitry and result with poor audio and video processing performance.
But the manufacturer , when designing these equipment , should implement utmost care to insulate the AC inlet terminals ,and provide total isolation.Especially from the conductive metal enclosing the circuitry and allow good clearance between them .And the enclosing conductive material should be built from solid ,rigid and robust material -not easily bendable -to reduce the risk of bending ,and hence from touching to the non-insulated live terminal .This could happen due to deformation after a damage impact or applied accidental pressure on the corners of the conductive panels , covers ,metal rear panels or top covers .
Without these measures taken ,the possibility of occuring 120 volts electric shock will increase much further . 120 volts electric shock could cause injury or even death depending on many factors such as wetness of the skin, area of contact, duration of contact,age,health condition and so many SEE FURTHER DETAILS .
Here is a graph of two-prong product with a fault of short circuit between not-bound-to-ground metal chassis and uninsulated live terminal , and it is undetected by the circuit breaker . Meanwhile the product is up and running ,the product will still work ! But once the unit is touched by the user and if the user is standing in a conductive position electric shock will definitely occur .
If any such an incident occurs , even if it was an electric shock that did not cause any injuries please report immediately to the Electrical Safety Authority (ESA)see also photographic illustration