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 range from 4,160 to 34,500 volts.
Secondary lines, or secondaries, are located lower down on utility poles, usually below transformers. Typical secondary voltages are between 120 and 240 volts. Although the voltage is lower, these lines can still deliver a severe electric shock if contacted.