From the Switchyard to the Home

Electricity first travels to the switchyard to step up its voltage after it has been generated at the generating station. After travelling over high-voltage transmission lines, and as it approaches cities, a source substation along on the route steps down the voltage and directs the electricity to secondary transmission lines. At the end of these lines, satellite substations once again step down the voltage for the electricity to move along the distribution network. This network brings electricity in our cities to our homes, public buildings and industry.

Substations serve to step up or step down voltage or to isolate or connect high voltage lines. Substations contain a wide variety of equipment: voltage transformers, instruments for measuring current and voltage, and protective equipment such as circuit breakers and surge arrestors.

The distribution network consists of wood posts set along roads and city streets. The poles generally carry 25 000 volt power lines. The presence of a transformer at the top of the pole steps the voltage down to 240 volts so it may enter homes. Increasingly, underground distribution networks are now being used.

Electricity in the Home

Electricity reaches the end of the road when it arrives at the home. From the generator where it was created, the electricity travelled at 735 000 volts over a distance of more than 1 000 kilometres, arriving in the home at voltages of 120 and 240 volts. Electricity enters the home through an electrical distribution panel equipped with a main breaker and circuit breakers or fuses. The quantity of energy consumed is measured by a meter located outdoors and connected directly to the power supply circuit breaker.

The main breaker serves to voluntarily cut power to the entire home. Circuit breakers or fuses, on the other hand, cut power voluntarily or automatically in the event of an overload. The electrical distribution panel is the start point of all circuits in the home. Circuits are conductors connected to each other that ensure the distribution of electricity within the home. Some appliances like refrigerators are powered by dedicated circuits. However, one circuit may serve to provide electricity to several small appliances such as toasters, computers or a series of lights. Appliances with powerful heating elements such as a stove, water heater or clothes dryer are fed by dedicated 240-volt circuits.

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