| Electrical cables are like the veins of all electrical | | | | Overload occurs when the current flowing is too |
| systems. As veins carry blood in our body, they | | | | high for the system. They don't impose any |
| carry electricity to run a number of appliances. | | | | immediate damage to the cables or surroundings. |
| The selection of electrical cables should be done | | | | The danger is supposed to enhance if the duration |
| according to the current, voltage and power | | | | of the overload remains for a longer period. In |
| requirements. | | | | that situation, due to overheat the covering will |
| While selecting a electrical cable, you must keep | | | | melt leaving the bare conductors exposed. The |
| two things in mind. | | | | heat can lead to cause fire. The main reasons for |
| - The cable you choose should be able to carry | | | | overloads in domestic setting are : plugging a |
| the current load without overheating. The cable | | | | heavy duty appliance into a supply insufficient for |
| should withstand the extreme conditions of | | | | that, and using too many consumer appliances at |
| temperature during its entire working life. | | | | the same time. |
| - The cable should provide sufficient sound | | | | A short-circuit occurs when live and neutral or live |
| earthing, to allow the fault current to trip the MCB | | | | and earth that bypasses an appliance is |
| or fuse in a short time, and to limit the voltage to | | | | connected. This connection will have a very low |
| which people are exposed to a safe level. | | | | resistance and the current flowing can be |
| The two major safety hazards that needs to be | | | | hundreds or thousands of times higher for the |
| controlled in a wiring system is Over-Current and | | | | system. This is called short-circuit current or the |
| Electric Shock. Protection against over-current also | | | | fault current. The short-circuit can happen if the |
| provides protection against electric shock. | | | | wires in a mains electrical plug become loose and |
| Over-current is the increase in the amount of | | | | touch one another. Handling short-circuits is not |
| current above the level for which it is designed. | | | | only important to protect cables, it is a part of |
| Over current are very dangerous as they lead to | | | | the protection against electric shock too. |
| a risk of fire. | | | | In domestic installations, short-circuit protection |
| When current flows in electrical cables it is normal | | | | and overload protection both are provided by the |
| that they become warm, and heat is generated. | | | | same device, either an MCB or a fuse. An RCD |
| The level of heat generated by electrical cables is | | | | can be used for additional shock protection. When |
| safe only when it is kept within reasonable | | | | the amount of current flowing exceeds a |
| boundaries. The standard PVC-insulated cables are | | | | specified limit for a certain time, the fuse will |
| designed to run at temperatures up to 70 | | | | break in the fuse or the MCB will trip. In both the |
| degrees Celsius. Anything beyond that can be a | | | | cases, the circuit will be opened and there will be |
| risk. | | | | no further flow of current. |