Electric Shock
|
|
Shocking Liar Electric Shock Truth Game Lie Detector $26.69 |
|
|
ultimate shocking Liar Electric Shock Lie Detector Q $18.25 |
|
|
Electric Shock Pen Joke Gag Trick Prank Funny Toy Gift $0.99 |
|
|
Cool! Ultimate shocking Liar Electric Shock Lie Detector $26.99 |
|
|
NEW fashion Lightning Reaction Revenge Electric Shock Game $18.80 |
|
|
Electric Shock Chewing gum Toy Green $2.83 |
|
|
Electric Shock Chewing gum Toy Yellow $2.83 |
Home Electric Shock Protection – Your ELCB Is Not Enough
Most home electrical installations have an ELCB of one type or the other installed at their electrical panels as a protection from electric shocks. Many electricity users also do check occassionally to make sure that the ELCB does work.
However, is this checking enough to make sure the household members are protected from the shocks that the ELCB is supposed to protect them from?
This aspect of the electric shock protection seems to have deceived many ordinary electricity users for a long time.
Checking the health of the ELCB is simple and you can do it easily. While the electricity is on (i.e. not during the mains blackout), just open the electric panel cover, locate the ELCB unit and the TEST push-button on it. The test push-button will test whether the ELCB unit is working properly or not.
Then gently push the TEST push-button on it. If it trips (i.e. the ON/OFF switch will snap and drop to the lower position. You can see the OFF label or symbol), then the ELCB is working properly.
Since the ELCB is working properly, then you are safe, right?
Wrong. The test facility provided on the home ELCB will only confirm the health of the ELCB unit, but that test does not confirm that the ELCB will trip when an electric shock hazard does occur. It is a really sad fact that all the while this misunderstanding has left many homes totally unprotected from the risk of electric shocks.
This brings us to the second requirement for the proper operation of a home shock protection system, which is the electrical grounding.
You can think of the ELCB as the brain for the shock protection, and the grounding as the backbone. Therefore, without a functional grounding there is totally no protection against electric shocks in your house.
An improperly grounded home electrical system is a serious hazard. In fact it is a serious hazard in any electrical system. Unfortunately this happens to be the most common violations of the electricity bylaws by electricity users. It shows how prone people and companies are to overlook how important the electrical grounding is.
As described above, making sure the ELCB works properly is easy. It can be simply tested by a Test Push-button on the unit itself, and it is recommended that the ELCB be tested once a month or after every thunderstorm.
However, looking after the ELCB alone is not enough. The electrical grounding system must also be in good working order for the shock protection system to work. In addition to the scheduled routine inspections that should be done by the qualified electrician, this grounding should preferably be inspected regularly at shorter intervals by the homeowner.
About the Author
Feel free to visit my blog at http://electricalinstallationblog.blogspot.com to read more on home electrical installations and other issues on shock protection.
How does the body feel electric shock?
I learned about the mechanoreceptors in the skin, and so I know that meissner corpuscles feel rubbing, merkel disks feel pressure, ruffini endings feel stretching and pacinian corpuscles feel vibrations. But, in that context, how does the body sense an electric shock, like from static? Is there a specific receptor for that?
An electric shock can occur upon contact of a human or animal body with any source of voltage high enough to cause sufficient current flow through the muscles or nerves. The minimum detectable current in humans is thought to be about 1 milliampere (mA). The current may cause tissue damage or heart fibrillation if it is sufficiently high. A fatal electric shock is referred to as electrocution.
Psychological
The perception of electric shock can be different depending on the voltage, duration, current, path taken, frequency, etc. Current entering the hand has a threshold of perception of about 5 to 10 mA (milliampere) for DC and about 1 to 10 mA for AC at 60 Hz. Shock perception declines with increasing frequency, ultimately disappearing at frequencies above 15-20 kHz.
[edit] Physiological
Burns – Tissue heating due to resistance can cause extensive and deep burns. High-voltage (> 500 to 1000 V) shocks tend to cause internal burns due to the large energy (which is proportional to the square of the voltage) available from the source. Damage due to current is through tissue heating. In some cases 16 volts might be fatal to a human being when the electricity passes through organs such as heart.
Ventricular fibrillation – A low-voltage (110 to 220 V), 50 or 60-Hz AC current travelling through the chest for a fraction of a second may induce ventricular fibrillation at currents as low as 60mA. With DC, 300 to 500 mA is required. If the current has a direct pathway to the heart (e.g., via a cardiac catheter or other electrodes), a much lower current of less than 1 mA, (AC or DC) can cause fibrillation. Fibrillations are usually lethal because all the heart muscle cells move independently. Above 200mA, muscle contractions are so strong that the heart muscles cannot move at all.
Neurological effects – Current can cause interference with nervous control, especially over the heart and lungs.
When the current path is through the head, it appears that, with sufficient current, loss of consciousness almost always occurs swiftly. (This is borne out by some limited self-experimentation by early designers of the electric chair and by research from the field of animal husbandry, where electric stunning has been extensively studied) [1].
Arc-flash hazards – Over 80% of all injuries and fatalities caused by electrical incidents are not caused by electric shock, but by the intense heat, light, and pressure wave (blast) caused by electrical faults. The arc-flash in an electrical fault produces the same type of light radiation from which electric welders protect themselves using face shields with dark glass, heavy leather gloves, and full-coverage clothing. The heat produced may cause severe burns, especially on unprotected flesh. The blast produced by vaporizing metallic components can break bones and irreparably damage internal organs. The degree of hazard present at a particular location can be determined by a detailed analysis of the electrical system, and appropriate protection worn if the electrical work must be performed with the electricity on. Worker safety standards in the USA require, though, that the electricity be turned off before work is performed unless a greater hazard will result from turning the power. Yah
