Understanding the Electricity Grid: What You Need to Know

We’ve all seen the poles and wires that line our streets and span across hundreds of miles of woods and farmland.  This is known as the electricity grid, and it has been around since 1882. As the electricity grid becomes more modern, it’s important to understand how our grid works.

The first electricity grid

On September 4, 1882, the Pearl Street station in Manhattan became the first commercial power plant in the United States.  This powerplant and the 100,000 feet or wiring that connected 84 customers were designed by Thomas Edison. Although Edison’s electricity transmission system used direct current (DC) and today’s electricity transmission system uses alternating current (AC), the general structure of today’s electricity grid is quite similar, though much greater in scale, to Edison’s creation.

The path from power plant to your home

Electricity has a unique trait that requires it to be consumed almost immediately after it is generated.  Often, electricity travels hundreds of miles from the power plant to a home where it is consumed by a light bulb or another appliance.  So how does it get there so fast?

Once it’s generated, electricity leaves power plants and travels long distances across high voltage power lines.  This process is called transmission. Transmission wires usually carry electricity at 110 kV or above. This voltage is nearly 1000 times greater than the wiring in your home.  Given the loss of energy via transmission the voltage must be this high in order to get significant amounts of energy from power plants to substations miles away.

Once electricity arrives at a substation, it is reduced to a much lower voltage, usually to 2400 volts, which is about 20 times greater than the voltage in your home.  There are over 55,000 substations in the United States.

After the electricity leaves the substation at a smaller voltage than when it entered, it travels across even more power lines until it hits a transformer in your neighborhood.  As their name suggestions, transformers are used to transform the electricity from 2400 volts to 120 or 240 volts. From the transformers, the lines are sent directly to your home or other buildings for end use.

An amazing fact about above ground power lines is that they are not insulated by any type of coating material.  They are naturally insulated by the air. Insulated electric lines would be very expensive, given the fact that there are over 450,000 miles of high voltage lines running across America.  Electricity will only leave a power line if it has a direct path to the ground. That’s why you should never touch a power line with anything if your feet are touching the ground or if you’re touching anything that might be touching the ground.  So be careful when working on ladders, using rakes to get leaves off your roof, or setting up a tent near a power line.


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