How Your Home Electrical System Works

Introduction:

Your home has a primary electrical circuit that comes into the home from the utility company. The electric circuit consists of a120 volt single phase hot wires and a neutral wire. The wires connect to the main electrical panel and a sub-panel if you have one. The main panel or sub-panel contains circuit breakers or fuses in older homes.

Only one breaker is used for each of the house electrical circuits. In some cases the breaker may supply two circuits such as a light circuit and a doorbell circuit. 

Each circuit consists of one 120 volt hot wire, one neutral wire and a ground wire. There are some specialized circuits that have two hot wires instead of one wire such as a 220 volt circuit. Each of the two hot wires carries 120 volts.  These circuits are commonly used for large capacity air conditioners, electric ranges and dryers.

All electrical devices and appliances have ratings listed such as 110v, 115v, 120v. These devices and appliances are all designed to run on a standard circuit. As electricity travels through the circuits it dissipates some of its energy and as a result the voltage drops. By the time it gets to the farthest outlet in the circuit the voltage may have dropped from 120v down to 106v. This voltage drop over a distance are normal and to be expected.

Electrical current is measured in watts, amps and volts. The voltage is analogous to water pressure. It measures the “pressure” of the electricity being “pushed” through the wire. Wattage is the quantity of electricity being pushed through the circuit. Amperage is the wattage divided by voltage. So if you see a device rated for 15 amps it means when supplied with 120 volts it is designed to handle up to 1800 watts, (15 amps 120 volts = 1800 watts).

Circuit breakers and fuses act as a switch and are designed to stop the flow of electricity when it gets too high. While a circuit breaker is very much like a switch, fuses have only a one time use and must be replaced each time they interrupt a circuit. With circuit breakers, if too much load (current) is placed on a circuit, the breaker “trips” and turns off the flow of electricity. Excessive loads may result from too many devices simultaneously in use on a circuit, a faulty device or a short circuit.

Without a circuit breaker or fuse, an overloaded device could be damaged and a fire could result from the heat generated by the device, wiring or from electrical sparking.  The national electrical code requires a special ground fault circuit interrupter (GFCI) on outlets in wet locations such as the kitchens and bathrooms. GFCI outlets trip very quickly reducing exposure to dangerous electrical current.

This is how you’re home electrical system works. When a home is wired by a professional electrician in accordance with the electrical code you can be assured that it is safely done.

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