Types of Power Lines: Know the Difference
Power lines and transformers come in different sizes, forms, and voltages. Learn about the differences between distribution lines, transmission lines, padmount boxes, and how to stay safe around each.
Distribution lines are medium-voltage lines that run in residential areas. Their voltage can range between 35,000 volts to 2,000 volts, with distribution mainly occurring underground in urban areas, and above-ground (pole-mounted) in rural communities and older urban neighbourhoods.
Although they carry less voltage than transmission lines, contacts with them are more frequent, and when working around them, the 7-metre rule should always be followed.
Transmission Lines and Towers
Transmission lines are high-voltage lines directly connected to power generating stations. Transmission lines are usually situated above ground, and can carry up to 800,000 volts. This high voltage is necessary for the power to travel longer distances while minimizing electricity loss. (There are also some underground transmission lines, but these are less common.)
Because of their high voltage, transmission lines usually run through special utility corridors, away from houses and people. As a result, most contact incidents with transmission lines occur while they are being operated on. When working on or around transmission lines, extra precautions must be taken. Follow the 7-metre rule and be aware of all the connecting substations, transformers, and underground lines.
A padmount or padmounted transformer is the type of green or gray electrical box seen commonly throughout urban and industrial areas, usually mounted on top of a concrete pad. These transformers are tied to underground distribution lines, which deliver electricity to nearby households and businesses.
Their secure and enclosed design means they can be easily installed in residential areas without additional fencing. Still, contacts with padmounted transformers are common, especially with cars and equipment. When digging near padmount boxes, always be sure to request a locate at least 5 days before beginning work.
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