287Kv disconnecting switch , were important in the spread of electrification on the West Coast of the United States during the 1910s - 1920s .
287Kv disconnecting switch , became essential to the New Deal 's mass - scale rural electrification efforts in the 1930s .
287Kv disconnecting switch , were important in the spread of electrification on the West Coast of the United States during the 1910s - 1920s , and became essential to the New Deal 's mass - scale rural electrification efforts in the 1930s .