Introduction:

With rampant urbanization in India, electricity has become a basic need. In agriculture sector also it plays an important role. Life with out its presence is almost unimaginable. It is the best friend of mankind but at the same time, enough care and precautions have to be taken while using it. It has caused many fatalities and injuries to the human life because of casual approach towards its use. According to a report published by Mumbai Fire brigade, 75 % fires in Mumbai are due to short circuits. During last five years around 8000 people have died due to short circuits in India. In addition to this, around 28 people die each day because of electric shock in India and these are the reported cases figures. Hence, it is important to carry out periodic inspection and maintenance of electrical installations especially in domestic segment where it is neglected a lot.

Technicalities:

Electricity in simple terms has a force which is called as Voltage which drives current through the wires when any electrical appliance is connected. The capacity of the appliance is measured in Watts. As per the wattage the appliance draws a current from the source for its efficient operation. The voltage is low voltage either 240 Volts Single phase or 415 Volts, three phase.

There are two major hazards as regards to electricity viz Short Circuit and Electric Shock. These two hazards need to be addressed by providing suitable protection system in the circuit.

General Causes of short circuit and electric shock:

• Old wiring. Even new wiring if the wires / cables get damaged during their installation and this damage goes unnoticed.
• Use of non branded products.
• Over loading a wire, sockets than its normal current carrying capacity.
• Absence of miniature circuit breaker (MCB) of adequate capacity to trip the circuit in case of over load.
• Lacunae while designing electrical system.
• Installation work not carried out by adequately qualified technicians. Lack of supervision.
• Absence of earthing conductor to the respective electrical equipment.
• No provision of RCCB (Residual Current Circuit Breaker).

Design of electrical system in residential premises:

• The expected connected load in Watts should be ascertained with probable growth in future.
• Demand factor should be taken as 60% of the connected load.
• The electric meter, mains cable should be of sufficient capacity to supply the load safely. The provisions of IS 732 should be followed like the cables/wires can not be loaded more than 75 % of their rated capacity. Also temperature rise consideration should be taken while deciding the size of the cable. The current carrying capacity of the conductor reduces with temperature rise.
• The size of Miniature Circuit breaker (MCB) installed on the mains cable should be so chosen that it will protect the mains cable from over load. The MCB size should be compatible with mains cable/wires size. The MCB should have sufficient short circuit current breaking capacity. The MCB should be provided at the point of commencement of supply i.e. in the meter room after the meter.
• If fuses to be provided, they should be HRC type having short circuit breaking capacity without getting damaged.
• In case of three phase supply there are two distinct earthing connection. One is given by the supply company and the other one to be provided by the owner of the electrical installation as provided in clause 16 of CEA safety regulations, 2010. In case of single phase supply the earthing connection is provided by the supply company.
• This earthing connection should be extended to each residential premises of that particular building. The value of earthing resistance should be less than 5 Ohms as provided in National Electrical Code (NEC).
• Inside the premises, the distribution may be made by using a distribution board having MCB on each of the outgoing circuit. The MCBs shall be of adequate capacity so that they can carry the require load safely while protecting the wires on which they are installed against over load so as to prevent short circuit.
• As provided in clause 42 of CEA safety regulations, 2010, there should Residual Current Circuit Breaker (RCCB) installed in the distribution board wherever the load is more than 2 KW for protection against electric shock.
• Care should be taken to decide upon the size of the wires used for heating load like Geyser, ACs, Microwave, OTGs etc. The power sockets used for such load should be of sufficient capacity to carry the current safely without getting burnt. Suitable switches should be used for such load. Geyser switch should be installed away from the geyser in side bathroom.
• All the switch boards/ distribution boards should be easily accessible for operation, especially during emergency.
• Load of the kitchen gadget should be ascertained properly. Suitable size power sockets should be used so that there is no burning of sockets.

Precautions to be taken while using electricity:

• Never operate switches with wet hands.
• Always keep the AC, TV etc. OFF from power switch board. Don’t just operate on remote control. Preventive maintenance of all the electrical gadgets should be carried out periodically
• Keep a small fire extinguisher ready in side house.
• In kitchen, the heating equipment should not be kept below switch boards.
• Preventive maintenance of the entire electrical system should be carried out every year. This shall include tightening of all the connections, checking earthing connection to each power socket of the premises.
• Carrying out electrical safety audit every five years as a good practice.