Fourth, see if the register is direct-reading, i.e., has no multiplying constant. Some registers are not direct-reading in that they require multiplying the dial reading by a constant such as 10 or 100 in order to obtain the true reading. If the register bears some notation such as “Multiply by 100,” the reading as indicated by the pointers should be multiplied by 10 or 100 as the case may be to determine the true amount of energy consumed.
Some of the earlier forms of meters were equipped with what is known as a “non-direct-reading register.” In this case, the reading must be multiplied by the figure appearing on the dial as just explained, but the dial differs from those just described in that the multiplying constant is generally a fraction such as ½, etc., and the dial has five pointers. This older style of register reads in “watt-hours” of “kilowatt-hours.”
Fifth, the reading of the dial does not necessarily show the watt-hours used during the past month. In other words, the pointers do not always start from zero. To determine the number of watt-hours used during a certain period it is necessary to read the dial at the beginning of a period and again at the end of that period. By subtracting the first reading from the second, the number of watt-hours or kilowatt-hours used during the period is obtained.
The meter man, having in his possession a record of the readings of each customer’s meter for the preceding months, is thus able to determine the amount of energy consumed monthly.
EXAMPLES OF METER READINGS
Fig. 253a shows an example of an ordinary dial reading. Commencing at the first right-hand pointer, Fig. 253c, it is noted that the last figure passed over by the pointer is 1. The next circle to the left shows the figure last passed to be 2, bearing in mind that the direction of the rotation of this pointer is counter-clockwise. The last figure passed by the next pointer to the left is 1, while that passed by the last pointer to the left is obviously 9. The reading to be set down, therefore, is 9121.
Fig. 253b.—This dial reads 997 kilowatt hours.
Fig. 253c.—This dial reads 9121 kilowatt hours.