Electricity 



237 



FIG. 135. An arc lamp. The carbons are much larger than the carbons 

 in the pencils, and the arc gives an intense light. 



Keeping arcs from forming. Well-wired houses have 

 the wires brought in through iron pipes, called conduits, 

 and the conduits are always grounded; so if an arc 

 should form anywhere along the line, the house would 

 be protected by an iron conduit and if one of the loose 

 ends of wire came in contact with the conduit, the cur- 

 rent would rush to the ground through it, blowing out a 

 fuse. The next section tells about the purpose of fuses. 



The directions that usually come with electric irons, 

 toasters, and stoves say that the connection should be 

 broken by pulling out the plug rather than by turning 

 off the switch. This is because the switch in the electric- 

 light socket sometimes loses its spring and instead of 



