The Cost of Electric Service

Ladies' Mirror, Volume V, Issue 2, 2 August 1926, Page 58

The Cost of Electric Service

The two most familiar questions asked concerning every domestic electrical appliance are —what will it do? and, what will it cost to use? The first question must be dealt with in respect of each individual piece of apparatus, and the more important ones are discussed later. The method of determining the cost of operation is the same for every device. First, it is necessary to know the rate at which the appliance will consume electricity when in use. This is measured in "watts," and may be ascertained in most cases by

reference to the maker's label affixed to the machine. A few appliances carry no such indication, however, and for these reference would have to be made to the makers or their New Zealand distributors. Quite a fair proportion of appliances will be found stamped, not in "watts," but in volts (v) and amps (a). In such cases, to ascertain the watts, it is only necessary to multiply the numerical values given for volts and amperes together, the product being "watts." Thus an electric iron labelled 200 v. 2.5 amps will in use consume electricity at the rate of 200 x 2.5 = 500 watts. It is, of course, perfectly obvious that one appliance rated at 300 watts will consume electricty at double the rate of another marked 150 watts, and at only half the

rate of a third rated at 600 watts. Now, the quantity of electricity an appliance consumes naturally depends on the length of time it is in use, and the time-factor must be taken in account when determining "quantity." One hour is the timeunit commonly used, and a 300-watt appliance in service for one hour is said to consume 300 x 1 = 300 watt-hours. Similarly, in two hours the consumption would be 300 x 2 = 600 watt-hours, and again in half an hour it would be 300 x i = 150 watt-hours. In exactly the same way the quantity of electricity

consumed by any electrical appliance is ascertained by multiplying its watts by tbe time, in hours, during which it is used. Expressed as a formula that can easily be remembered, this is : Rate of electricity consumption x time in use = quantity. atts x hours = watt-hours. jTp i.ectkicitv is sold by the unit, as every consumer knows. But what is one unit? Simply the quantity of electricity indicated by 1,000 watt-hours. For convenience it is generally referred to as 1 kilo-watt-hours (just as 1,000 metres is designated 1 kilometre). The essential thing to grasp is that when a consumer pays an average of, say, lid to 2RI per unit, or whatever amount is charged in his area of

supply for a unit of electricity, he receives 1,000 watt-hours of electricity for that money. In the Dominion the cost per unit charged by the different electrical power boards varies from Id to 2id.

The method of arriving at the cost of using electrical appliances will now be quite plain. The quantity of electricity consumed is ascertained, as indicated previously, and this value divided by 1,000 gives the number of units of electricity used; multiplied by the charge per unit, this gives the actual cost.

Electricity is generally regarded as a mysterious agency, but there is nothing occult about its sale and purchase. The meter which registers a user’s consumption does so in units, and is very easily read.

WE will now turn to the consideration of what electrical appliances will do. That they give of their best, and prove reliable in service, it is necessary that they be used and manipulated with a reasonable amount of common sense. And in view of any misapprehension that may exist, it will be as well to emphasise that it is only ordinary fair treatment that is required.

At the end of this article arc given data and information in summarised form concerning the cost of operating the more familiar domestic electric appliances. Fair average figures for the rates at which the various appliances named consume electricity when in use arc given. Actually, of course, the wattage of fans, toasters, irons, etc., varies with the particular make, but the figures may be taken as representative of good modern practice. The nature of the appliance and the reader’s own experience will supply the best criteria as to the reasonableness of the time estimates given, i.c., the number of hours each appliance will be used per week in ordinany circumstances. The amount of electricity each appliance, when used the stated number of hours, will consume in a week, is also given in units of electricity. (It is simply the product of the watts multiplied by hours, divided by 1,000, to express the result in units.) Finally are given figures, at Id per unit, of the cost per week.

THE figures of cost are worked out on the basis of Id per unit. This is simply because it is the most convenient tariff to take. Other tariffs involve multiples of one penny, and, where a consumer pays a different rate —say I’d, 2d, or even 3d, it is only necessary to multiply the cost figure given by the corresponding proportion (1 Ad, 2d, or 3d) to ascertain what the actual cost to the consumer at the rate of charge in her own home. Incidentally, it may be mentioned that there are already over eighty areas where Id a unit service indicated would be to that or less is charged for energy used by domestic appliances such as those

listed, and the number is increasing rapidly. The tariff, or charge, for electricity naturally becomes more important the greater the quantity of energy an appliance consumes. Be it noted, however, that appliances such as fans, bed-warmers, washing-machines, vacuum cleaners, sewing-machines, motors, etc., consume such a small amount of electricity that the cost of their operation would be small even were they used on the lighting circuit with a tariff as much as 6d a unit.

Electric Irons AV HE electric iron being the -*- most widely used appliance of all domestic labour-saving devices — other than lighting applications—will doubtless be familiar to most readers. In form it is much like the ordinary flat-iron one heats over the fire or gas-ring, though a much more presentable article with its highly-polished, nickel-plated finish. In the body of the iron is a special resistance wire which is heated by the passage of an electric current through it when in use. Heat passes to the sole plate, which quickly becomes sufficiently hot for any ironing purpose. Means are provided, however, which prevents the flow of heat to the handle of the iron, which remains cool no matter how long the iron is used. As the supply of heat is continuous during the whole of the time the current is switched on, ironing can be carried on continuously without those periodical waits for the iron to get hot, or trips to and from the fire to replace a cool iron with a hot one, which are unavoidable when the ordinary flat-iron is used.

Unless a lot of heavy ironing is being done, the iron will probably not need to be switched on the whole of the time; switching off for a few minutes at a time as necessary, prevents the iron getting too hot and scorching the clothes, and also saves current. There is a fair amount of heat stored in the iron, and it is possible to finish off the last few things with the current switched off.

Electric irons arc made in a large number of sizes, but even with the larger size the cost is usually not more than Id per hour.

/ ~j n 'HE electrical washing-machine brings laundry methods into the home and permits the most delicate fabrics to be cleaned with the certainty that they will not be damaged. Properly speaking, the clothes-washer is a mechanical contrivance, the only electrical parts being the motor, which supplies driving power, and its control gear. But the electrical is the laboursaving part.

A wringer, driven by the same electric motor, is provided on the washing machine and the clothes are passed straight through it from the container. Though small, these

wringers are very efficacious, and will handle blankets equally as well as fine lace and silk articles. A -4-h.p. motor, taking electricity at the rate of about 200 watts, is sufficiently powerful for driving domestic clothes-washers and is the size usually fitted. It consumes one-fifth of a unit of electricity per hour, which, at Id per unit, costs less than id. A heavy week's washing can be done in three to four hours at the most, at a cost for electrical energy of less than Id, and that, too, without any of the hard labour normally associated with this particular domestic duty. Vacuum Qleaners THE principle on which the electric vacuum cleaner operates is similar to that of a fan. A small electric motor drives a specially designed fan at a high speed. As the machine is so arranged that air can only enter at the cleaner nozzle, a suction action is created sufficiently powerful to suck up the dust and dirt from, on, and under the carpet. The dirt is carried through the machine and deposited in a bag or other receptacle, and can then be emptied straight into the dust-bin. Individual makes differ in being fitted with power or friction-driven brushes or other rotating members, which, acting on the carpet, assist in the work of cleaning. There are few parts of a house. if any, that cannot be cleaned by the modern electric vacuum cleaner. The motors fitted are usually of about Jth-h.p., corresponding to a consumption rate of less than 150 watts. An hour's continual operation, therefore, costs about ith of a penny at Id per unit. Twopence would purchase sufficient electrical energy to keep the whole house clean from Monday to Sunday. Electric Heating MANY readers have doubtless had practical experience of the difficulty of obtaining figures of the cost of heating their homes electrically. There would be no trouble about giving such information with accuracy if an inquirer could state his heating requirements definitely. But therein lies the difficulty: he cannot. The amount of artificial heating required to produce comfortable conditions in the home varies from day to day with the atmospheric conditions, and the prophet is not yet born who can give accurate weather forecasts in this country. One might hazard average figures, but the degree of error to which they would be subject makes it unwise to do so. When putting in electric fires for general heating, sufficient heating capacity must be provided to warm the room quickly in the coldest weather. But this maximum capacity is only used for a comparatively short period; most of the time heaters arc used on medium or low heat, and it would

be necessary to know the length of time the fire was on circuit for each of its different degrees of heating before the consumption and cost could be calculated and predicted with certainty. If the reader uses an electric radiator for such purposes as bedroom, study, or den heating, a good idea can quickly be obtained as to whether general electric heating is desirable and reasonable in cost. If the tariff rate is right, say Id or lid, or even 2d in some cases, the answer will probably be in the affirmative.

To deal fully with all the electric aids to the housewife would occupy too much space. The brief particulars at the end of this article must suffice as a guide. In any case, from the information already given, readers should have little difficulty in estimating with a fair degree of accuracy the service and cost factors of any particular appliance in which they may be interested.