388 



GENERAL SCIENCE 



the bill rendered is too high or too low. If it is too high for 

 one month, it will be too low the following month; consequently 

 the consumer will not lose, if the meter is correct. 



Most electric companies are interested in keeping the meters 

 accurate, and will usually make any test upon any meter whenever 



asked. Applications should 

 be made to the Electric Com- 

 pany, and not to the meter 

 reader or bill collector. Since 

 no measuring device can be 

 absolutely accurate, a 4 per 

 cent tolerance above and be- 

 low the amount which the 

 meter usually reads is always 

 allowed. Meters are usually 

 tested so that they will not 

 be more than 1 per cent either 

 'fast or slow. 



Causes of Fire. Electric 

 wiring of buildings must be 

 done by competent people, 

 since wires which are too 

 small to carry the amount of 

 current necessary for the con- 

 sumer may become very hot, 

 if too much current passes over 

 the wire. This burns off the 

 insulation, and sets fire to 

 the building. Wires should be 

 drawn in steel or iron pipes 

 called conduits. This not only 

 provides against danger of fire, but allqws a defective wire to be 

 pulled out and a new one substituted. Wires which are used in 

 an extension from the lamp socket should be well constructed. 



Insulation. Electricity is conducted over some substances much 

 more easily than over other substances; for instance, electricity 

 runs over copper wires easily, but it does not pass through rubber. 



FIG. 267. Cross-section of house, showing 

 spaces between partitions and floors 

 through which electric wires are easily 

 fished (or drawn) without any dis- 

 figurement to the room interiors. 



