Electrical Service Panels and Circuit Breakers

Many homeowners are looking to add electrical capacity to their homes. This often requires new wires from the electric company, a heavier service panel and a permit.

The service panel (also called a fuse box or breaker panel) is the central hub that distributes electricity to switches, outlets and appliances throughout your home. It is usually located in a garage or utility area.
Electrical Circuits

An electrical circuit is a closed conducting path in which electric current can flow. It can consist of either a single or multiple circuits that are connected in series, parallel, or a combination of series-parallel circuits.

When you flip a switch on a light[], TV, vacuum cleaner or computer, you complete an electric circuit. This allows the flow of electrons from the power source through wires to the appliance and back again to the source.

Electrical wires are usually colour coded, with black representing the grounding conductor that carries excess charges to the earth. The colour of the wires also indicates the amount of current they are allowed to carry, based on their insulation type, thickness and temperature rating.

The most common residential service voltage in North America is 120/208 volt wye, which powers 120 volt plug loads and lighting, as well as larger 277 volt single phase appliances. In larger commercial buildings, 347/600 volt is common.
Circuit Breakers

The circuit breakers in your electrical panel protect you from a fire. They are lever-operated switches that cut off power to any electrical circuit if it becomes overloaded. The two power wires that run into your breaker box carry 120 volts each, for a total of 240 volts. The main breaker attaches to these wires, which then connect to the hot buss bars, where individual branch circuit breakers are attached. If a branch circuit is pulling too much power from its wires, the internal sensing mechanism in the breaker heats up and causes the breaker to “trip,” or shut itself off.

This cuts off the flow of electricity before it can generate a spark that would turn into a fire. There are different types of circuit breakers, based on the medium used to break the arc and on their short-time rating. Examples include AFCI breakers, which are ideal for homes with old, frayed wiring; residual-current devices (RCD), which detect imbalance and provide overcurrent protection; ground fault circuit interrupters (GFCI), which prevent shocks from electric currents that return to earth through wiring or fixtures; and voltage-operated life-control breakers (VOLCB), which monitor the integrity of the wires on your home’s service grounding system.

Wires are the path electrons use to get from the power source to electrical components, such as a light bulb. They have a conductive inside and non-conductive insulation on the outside. The wires are color-coded to distinguish them from each other.

There are two main types of electrical wiring in homes and buildings: wires and cables. Both are insulated, but they are designed to carry different electrical currents and serve different purposes.

A single stranded wire is made of multiple individual insulated conductors that are intertwined together. It can be either uncovered or covered by a colored sheath. Stranded wires are more flexible, kink-resistant and stronger than solid ones. They are also easier to manage.

Most wires are coated in an insulating material to prevent electrocution when handling them. This sheath is usually composed of plastic or rubber-like polymers. If they are left unsecured or tangled, they may lose this protection and increase the risk of electric shocks.
Service Panel

Known in the industry as a breaker box, or formerly a fuse box, this central hub distributes electricity to switches and outlets in a home. It also houses the main breaker switch that shuts off the entire house. It’s vital for anyone who owns a home to know where this main switch is and how to operate it.

The service panel also provides circuit breakers or fuses that protect the wiring from too much power, which may cause it to overheat. They also ground the system to the earth, which prevents electric shock.

Be careful when working on the service panel, especially with screwdrivers or other tools. Unlike receptacles, which may only give you a slight shock, touching the service wires inside the panel will cause serious injury or death. Keep a distance when using tools and never touch the outer service wire ends at the lugs, even with the cover removed. This is the most common source of fatal electrical shock.Electrician