Electricity is boon to mankind. We cannot think of a world without electricity. It is a useful servant to us and it does many things for us. An electricity failure renders us really helpless. So much is our dependency on electricity that we cannot think of a world without electricity. At the same time we know that electricity is dangerous. How can one ensure electrical safety at home?
The dangerous conditions caused by electricity are electrical shock and occurrence of fire due to electricity.
Protection from Electrical Shock
We experience electrical shock when electricity passes through our body. Consider a situation. Someone is using an electric iron. Unfortunately for him, it had already developed an internal fault and due to it the metallic body of the iron is remaining live. That is, electricity is present on the metallic body of the iron. Then if he touches it, or any part of his body comes in contact with it, he may get an electric shock. It happens because when one touches anything that carries electricity, an electric current flows through his body to the earth. The amount of current that flows through one’s body depends on many factors, and if it happens to be sufficiently high, an electrocution may result. One may get an electric shock from any other household electrical gadgets like refrigerator, electric heater, microwave oven etc.
Methods for Protection from Electric Shock
Use of 3-pin Electrical Plugs
How can we protect ourselves from getting an electric shock in such a situation? Simple, the electrical wiring at your home should be done in a standard manner. The electric plug sockets should be suitable for 3-pin plugs and they should be properly earthed. Also you should use 3-pin plugs only to connect gadgets and ensure that the earthing pin in the 3-pin plug is connected to the metallic body of the gadget. In that case, even if the body of the gadget becomes live, the main part of the current flows to the earth through the earthing pin of the plug and the current flowing through the body of anyone who touches the gadget will be small and so he may be saved.
Use of Earth Leakage Circuit Breaker
There is yet another and more accurate method for protecting one form electric shock. That is by using a device known as E.L.C.B or Earth Leakage Circuit Breaker. The ELCB in your home shall have a sensitivity of 30mA. That is, when a current of 30mA (i.e., 30 milli ampere) or more flows from your electrical system to the earth (it may be through someone’s body), the ELCB will act and switch off the power supply instantly. The significance of this value of leakage current, i.e., 30mA is that it is at this magnitude and above the current flowing through human body becomes dangerous and can be fatal. So install an ELCB (also known as RCCB or Residual Current Circuit Breaker) of 30mA sensitivity for protection from electric shock.
Simple Precautionary Measures to Avoid Electrical Shock
Apart from the use of an ELCB, you can adopt some simple precautionary measures to avoid electric shock. They are as below.
1. Never switch on or off any electrical appliance with wet hands.
2. Spread rubber mats on the floor in front of switch boards. Then one will step on to it to operate any switch. Standing on a rubber mat and operating a switch makes it safer.
3. While using gadgets like the electric iron etc., either put on a pair of rubber or plastic footwear or operate them standing on a rubber mat or wooden plank.
4. In case anybody gets an electric shock, don’t touch him in an attempt to rescue him. You should first of all switch off the power supply and then only touch him.
5. Never touch a bare conductor in the electrical system.
Fire Hazard Due to Electricity
Now, about another hazard that electricity can cause, that is fire. The reasons for occurrence of fire due to electricity are listed below. Avoid them to ensure electrical safety.
1. Electrical short circuit.
2. Over load or over current in the electrical system.
3. Use of electrical wires or conductors of lesser thickness which are not capable of carrying the required current.
What is an Electrical Short Circuit?
When the output terminals of a source of electricity get in direct contact with each other, it is called a short circuit. Similar to the positive and negative terminals of a battery, the electric supply we get at home also have two(or more in case of 3-phase supply) terminals which the electricity supplier provides us through two wires. These supply terminals known as the phase and the neutral reach every part of our electrical system through the electrical wiring.
If the phase and the neutral come into direct contact with each other, an electrical short circuit results. This causes a heavy current to flow through the electrical wiring which will produce great heat and burn out the wiring and may cause a major fire.
What is Over Current or Over Load?
Over current or over load is said to have occurred when a current higher than the electrical wiring can handle flows through it. It may be due to some high capacity gadget being connected to the electrical circuit, which draws more than the current for which the circuit wiring was designed for. For, example, if one connects a heater to a lighting circuit, an over current may result. Heaters should be connected only to power circuits through power plugs, and not to lighting circuit through ordinary plugs. Over current also produces heat in the conducting wires and causes fire.
Protection for Short Circuit and Over Load
Use of Fuse for Protection from Over Current
In earlier days fuses were widely used in houses for protection against over current and short circuit. Fuse wire is a thin metallic wire designed to carry a certain current. This is fixed on a porcelain carrier and plugged into a base unit also made of porcelain. It is installed in a circuit such that the entire current in the circuit flows through it. The current rating of the fuse wire is selected according to the current for which the circuit is designed. So, when an over current results, the fuse wire burns forming discontinuity. Thus it disconnects the circuit from the power supply. In this manner the fuse avoids hazards due to short circuit and over current.
Use of MCB for Protection from Over Current
Now, a device known as M.C.B. or Miniature Circuit Breaker is available which can replace the fuse. With the introduction of the MCB some years back, the fuse has become somewhat obsolete. Now, fuses can be seen only in old electrical wiring.
The MCB looks like a switch. If an MCB is installed in your electrical wiring, it will act in the event of a short circuit or overload and switch off the supply automatically. Then you need only to simply turn on the MCB like a switch, of course after removing the cause of the short circuit or over load. How to remove the cause of the overload or short circuit? If the MCB got switched off (or ‘tripped’ as the technical term goes) when you switched on your heater, you can assume the heater caused the over current and resulted in the MCB getting switched off. So, switch off the heater before switching on the tripped MCB.
Advantages of the MCB over the Fuse
The MCB has some advantages over the fuse. Firstly, the fuse-wire has to be replaced every time it blows. A layman will not find it very easy. At the same time, the MCB just switches off automatically in the event of an over current and one has to simply turn it on like a switch.
Fire Hazard due to the use of under capacity electrical Wires
The third cause for electrical fire as mentioned above is the use of under capacity wires. When one connects a gadget with a wire which is not having sufficient current carrying capacity compared to the needs of the gadget, the wire may get overheated and catch fire. For example, if you connect your heater or electric iron, using a thin plastic insulated wire, it (the wire) may burn out.
Summary of How to Ensure Electrical Safety at Home
The important points to ensure electrical safety can be summarized as below.
1. Install an ELCB (or RCCB) in your electrical wiring. Its sensitivity shall be 30mA (or 0.03Ampere). It will protect you from electrical shock.
2. Install MCB instead of fuse. It will protect from hazards including fire caused by an over current or short circuit.
3. Follow the suggestions under the heading ‘Simple Precautionary Measures to Avoid Electrical Shock’ given above.