Fire due to short circuit” is a common cause that we read about, whenever there is a fire incident, be it in high rise buildings, apartments or even smaller dwellings not forgetting the industrial set ups, which have figured prominently in fire incidents of recent years.
For the present day trend of multistoried apartment buildings , highrises with offices, shopping malls etc., and even smaller buildings where the requirement for electricity involves multiple appliances (washing machines, dryers, heaters, microwave ovens etc) the electrical design aspect for buildings has assumed all the more importance simply for safety purposes.
The problem of fire due to short circuit gets even more acute due to lack of proper training of contractors, mindset of customers and developers to save cost and get the electrical work done at the cheapest possible way and electrical design in most cases is an afterthought once the entire establishment is already completed, whereas, it should have been thought of at the very early stage of design. Also at times there are elaborate designs but are not followed by the contractors, later when there is any problem no one can go by the plan that's on a piece of paper.
In layman terms, a short circuit is the coming together of wires carrying dissimilar types of “current”(as we say). Some others would say that the hot wire coming in contact with the cold wire is the cause of short circuits. That is not the strict or complete definition in technical terms yet is good enough for a basic understanding for “beginners”.
To put it in a better and one that is comprehensive perspective, whenever we use an electrical appliance (light, fan, aircon, refrigerator, etc), we allow “current” to flow through the wires into the appliance which converts the electrical energy into our required form (e.g. mechanical motion for fan, light energy for lighting etc).This current flows through wires and therefore the wires have to be of the appropriate size/capacity to bear the “load” that it serves. For example, the wire that conducts current to an aircon has to be of greater capacity than one which may be used for an energy saver light. Of course, it goes without saying that the wire used for an aircon can be used for an energy saver light without short circuit worries, but not vice versa.
The simple reason is that when the current passes through the wires, heat is generated, and the wires must be designed to safely withstand that heat. If that is not done then overheating of the wires may cause the protective covering(insulation) on them to melt and short circuit may occur due to the “hot” and “cold” wires without the protective covering, to come together. Further, the melted insulation may fall on combustible material below (wood, clothes etc) and start a fire. The wires themselves may catch fire that will spread along the wire.
The above is a very simplistic description of a short circuit, that we often hear or read about. In real life it involves multiple wires with “current” in different phases, which interact very much like the “hot” and “cold” wire concept, outlined above. It also involves the selection of the right type of switchgear (switches, plugs, circuit breakers etc) which are used to distribute the “current”.
Many of our contractors/workmen do not have the requisite qualifications for such designs and they work based on past experience or thumb rules that they have picked up along their way. The designing aspect should be undertaken by professionals in the field which require interaction with other disciplines during the design phase. The design would take into consideration the requirement, the type of equipment that will be used in the building,the use pattern at different times of day, month and year, the safety factor, the aesthetics desired by the customer which may sometimes lead to an unforeseen hazard and would have to be resolved in a safe manner and a host of other considerations. All these require not only someone with a degree or a licence but also with adequate design experience. The certified “as built” drawings of the designs should be available to investigate the causes, if there is an accident/incident at any later date.
Over the years, many of our local consulting firms have successfully grown with adequate capability and experience to undertake complex designs. For simple buildings (2~4 storied housing etc), many would argue if it is prudent enough to go to them and spend a substantial amount of money, for their services. For more complex buildings, industrial and manufacturing setups, it would certainly pay rich dividends in the long run as it would save the entrepreneur from heavy losses due to fire, lost lives and multiple hassles resulting from such occurrences.