Primary lines, or primaries, are higher-voltage lines located at the top of utility poles, above transformers. Primaries are usually made out of copper or else steel encased in highly conductive aluminum. Typical primary voltages include 4,160 volts, 4,800 volts, 13,200 volts or even 34,500 volts.
Secondary lines, or secondaries, are located lower down on utility poles, usually below transformers. Typical secondary voltages are between 120 and 280 volts. Although the voltage is lower, these lines can still deliver a severe electric shock if contacted.