230400 volts transformers ensure electricity reaches polemounted transformers thousand volts usable voltage common types reliably types voltage surges service transformer distribution transformer lights appliances reliable supply essential components feasible importance overhead lines installed underground serve commercial concrete pads utility poles customers efficiently strategically located protect customers customers premises primary function north america unsung heroes pivotal role intricate network distribution lines electrical devices power distribution system final voltage transformation electrical power system provide electrical isolation regions key functions top amc provider