ELECTRIC SERVICES

Greymouth Evening Star, 9 February 1929, Page 12

ELECTRIC SERVICES

DOMESTIC PRECAUTIONS.

In Victoria practically every domestic service carried out by electricity is now supplied at a pressure between 200 volts and 240 volts. There is (says the annual report of the Victorian lire Brigades Board) a wide impression that such a pressure is not dangerous, and that, although temporarily painful, a shock from it can do no harm. That this belief is unfounded is strikingly illustrated by the wide practice in many countries of adopting a 110-volt domestic service in place of a 200-volt service. The lower pressure can be handled without fear of a dangerous shock, although, of course, it may cause electric fires. It has not been adopted in Australia because transmission losses on a 200-volt service aie much less than those on a 110-Milt seivice, while wiring and other equipment is more expensive for a 110-volt supply than for a supply at 200 volts. If fur ther confirmation of the dangers of the electric supply mains is required, it is provided by the fatal accidents that have occurred. The effects which an electric shock produce depend • on a number of factors. Of these the constitution of the individual is not the least important. A shock that would cause only a slight temporary pain to some people may prove fatal to others. The portions of the body through which the current passes also largely determine its effect. A shock applied through the head or upper parts of the body is far more dangerous than one confined to one arm or one leg. The manner in which the current is applied is also important. The main resistance of the body to the passage of a current is centred in the skin. The electrical resistance of the internal tissue is comparatively low, but if the skin is dry and unbroken its resistance is high, and has the effect of very much lessening the shock. A moist skin, on the other hand, has a greatly lowered resistance, and if the skin is wet, or if a current is applied to an open wound, its effects may be serious. The area of contact with the skin also determines the amount of current which may pass when a shock is received. A shock caused by brushing lightly against a live wire will be much less severe than one obtained if a live conductor of considerable area is grasped. Most electrical installations are carefully made, and so designed that all live conductors are fully protected. Unless they are meddled with by unqualified people it is most unlikely that they will become in any way dangerous. Equal care is taken in the protection of electrical domestic appliances. In radiators, toasters, and similar healers, the heating element carrying the current is generally exposed to the air, but protected with a grating to prevent the owner touching the live wires. No metal object should ever be allowed to enter this grating. In fans, vacuum cleaners, and most forms of electric ranges, the live wires are either completely enclosed, or so protected that they can only be reached by deliberate tampering. No householder should touch any part of any electrical equipment that he does not thoroughly understand. If a fault develops, it should be left to be repaired by a qualified electrician. Not only may “first aid” methods applied by the owner endanger his own life, or cause a serious fire, but most electric equipment is very susceptible to serious damage by unqualified interference. DANGEROUS PRACTICES.

In many homes dangerous practices are daily engaged in in dealing with electrical equipment. One of the most common of these is the use of uncovered switches. The tumbler- switch used in the majority of homes has been found one of the safest and most effective electrical devices that has yet been produced as long as it is not interfered with. If the brass cover is unscrewed, however, the live contacts are exposed, and can easily be touched. In the domestic electric service, one of the two conductors which supplies the current is connected to the earth. It follows that if a person who is standing on the earth touches the other conductor a circuit is completed through his body to the earth. Boots, unless made of rubber, seldom offer- much protection from such a shock, as moisture from the ground, and from the feet, renders the soles partially conducting. Shocks may often be obtained even on the floor of a building if it is wet, or if, as is sometimes the case, it is lead-covered. Kitchen and bathroom floors are fre quently coated with lead. In such cases, the danger of accidental contact with live electrical equipment is grave. Another dangerous practice is the manipulation of switches with wet hands. Even when a switch is covered water may run under the cover, and cause the escape of current to the metal, button or cover, thus rendering the outside of the switch “live.” The danger of this practice is most pronounced in bathrooms, where a person witli bare feet, on a 'wet floor, may easily receive a fatal shock. On no account should electric lights or any electrical equipment be touched when one, is standing in a bath. Domestic switches sometimes develop contact faults which the householder attempts to repair himself. It is

strongly recommended that this work should be left to a qualified person, but if one feels himself capable of undertaking it should be careful to see that the main switch of the building is turned off before opening the faulty switch case. A wooden rod, or at any rate a wooden-handled tool should be used to make the repair. In Victoria several fatal accidents have occurred though the use of appliances, such as electric irons, on which the connecting cord has become frayed so that the conductors are exposed. Any sign of wear on connecting cords should be carefully watched, and, if necessary, the cords should be replaced by an electrician. In recent years the electrical dangers in a home have been slightly increased by the use of carelessly installed wireless sets. In Great Britain recently a woman received a fatal shock when using a crystal set, the wiring of the set having come into contact with portion of the electric installation of the house. There is a real danger when aerial wires * are erected near electric light wires. If, in the event of the breaking of the aerial wires, portion of it falls across the light wires, the set may become “alive,” and persons using it will be endangered. One of the most likely causes of electrical fires is interference with the fuses protecting an electric installation. Eires are caused by some form of short circuit which causes a conductor carrying, an excessive current to heat until it ignites adjacent inflammable material. Much of the insulatI ing material used on wires is very, inflammable, and a heated conductor can

cause a fire without difficulty. The domestic fuses are so designed that they will melt and cut off current before the amount of current flowing into the house wiring can reach a dangerous value. When fuses do “blow” it is often the practice of householders to replace them themselves. This work should always be left to an electrician, because it is imperative that the fu-se be replaced by another that will “blow” when the current entering the system approaches the danger mark. If a fuse is replaced with wire that is too heavy, the new fuse will not melt when the’ current reaches a point at which the house wiring will become warm. A fire may then commence. f m—■naaa^———