ELECTRICITY HAZARDS IN THE LABORATORY : You've probably read about, or heard of, people falling onto high voltage rails or cables and surviving thousands of volts. As a contrast, you might have also had a small electric shock from the mains yourself. It does not mean that it is safe because it only needs a few milliamperes across the heart to stop it. There are serious physiological consequences of passing an electric current through the body. You will learn about how to calculate the current A current of 1 mA is recognised as the threshold of perception i.e., a I mA current through the skin causes a tingling sensation. A current of 6 mA - 10 mA is the let-go-current. A current beyond 10 mA is not safe, a higher current may produce muscular contraction which does not allow even to throw away the current carrying object. A current of 20-25 mA will cause sure death as it causes irregular contraction of the heart whereby it stops pumping.
From now on, you know just what to expect if you ignore electrical safety. You will read about the first aid treatment of electric shock of this course. However, if you are first on the scene of an accident where someone is in the process of being electrocuted, YOU MUST NOT TOUCH THAT PERSON. The first action to be taken is to isolate the victim from the electric power source. In other words, switch off the power either at the nearest appropriate mains socket or at the nearest cut-out or master switch.
Many a times the reason behind the electrical mishap is due to negligence of the very fundamentals of electricity. Some of the possible causes that may lead to a shock or cause an electrical mishap are given below.
1. improper wiring
2. improper choice of fuse
3. choosing wire of improper rating
4. deterioration in the insulation system
5. accidental touches
6. break in earthing system
7. improper operatioduse of unconventional tools
Let us learn the safe ways of handling electrical equipment so as to minimise electrical accidents in the laboratory. We begin with wiring a plug.