Getting Nerdy About Houses - Residential Electrical Panels

How Do Residential Electrical Panels Work?

Residential electrical panels or breaker panels are metal boxes that are used to regulate and distribute power to designated areas in your home. Power is distributed by wires that are connected to circuit breakers (or in older homes, fuses).  Circuit breakers regulate the amount of current designated to the wire that then carries the electrical current to the intended destination. The number on a breaker, for example, a 30 AMP breaker, indicates the maximum amount of amperage that the breaker will allow the connected wire to draw from the electrical panel. If more than the maximum is attempted to draw through the breaker, then the breaker will “trip” and cut off power to the wire. The tripping of a breaker prevents wiring damage, electric shock and ultimately protects your home from electrical fires. 

The power to the home comes from the utility company through the electrical meter and connects to the main electrical breaker. The main breaker tells you the total amperage allowable to the house. Most residential properties have 200 AMPS service, however, it is not uncommon to find houses with 150 - 200 AMP service. The main breaker also controls all power to the property, so, turning off the main electrical breaker will shut off power to the property. *

*Please note, shutting off the main electrical breaker shuts off power to the house, however, it does not shut off power supplied by the utility company. The wires connected to the main breaker will be energized and still very dangerous.

Electricity passes through the main electrical breaker and allows electricity to power the hot bus (also referred to as the charge) bar. The hot bus bar is the area of the electrical panel where circuit breakers snap into place with the intent of distributing power to specific areas of the home. The distribution of power occurs once wires are installed into the breakers allowing them to carry the electrical current to switches, outlets, ovens, HVAC units, etc. 

Additionally, located in the electrical panel are the neutral bus bar and the grounded bus bar. The neutral is an area where many wires (typically the white/neutral wires) are connected which helps to protect ‘hot’ wires from having too much current or overheating. The ground bus bar is an area where many wires (typically the green or bare copper/ground wires) are connected. In main electrical panels, the neutral and ground bus bars are connected, in sub-electrical panels, the connection must be separate. 

Also, in electrical panels, you will find the main bonding jumper. The main bonding jumper provides a ground connection between the neutral/ground bus bar and the electrical panel. The grounding connection is made via a bare copper wire that connects the neutral/ground bus bar to a ground rod driven into the earth or to the metal rebar found in the foundation of the home. This ground connection will allow any stray electrical current to pass safely into the surrounding soil as opposed to other areas of the home. Similarly, if the property has gas service, there will be a requirement for the gas piping to be grounded as well. 

Simply put, electric panels are metal boxes with an opening that are often built into a wall with multiple breakers for different circuits. An electrical panel has a main circuit breaker that regulates the power supply to the entire home. Several smaller breakers are responsible for controlling power surges in specific rooms or appliances. Each breaker has an ampere (amps) rating for the area it controls. Many homes have breaker boxes (or subpanel) for different areas. For example, you may have a subpanel electrical box for an addition or if you have a larger house. The partitioning prevents power disruption in the entire home when there is a surge in one area. 

Each circuit in your home is designed to carry a specific electrical load with a maximum limit. A box breaker operates at 80% of its rated capacity, so all the plugged devices should not exceed 80% of the amps for the specific circuit. 

If the load exceeds the threshold, the break shuts off or trips. This can be due to too many devices plugged into one circuit or if one appliance consumes too much power. If a breaker trips, you should unplug some devices and then flip the switch to reset it. 

The purpose of an electrical panel is to provide sufficient power to areas of the house using wires. It also uses breakers and bus bars to regulate the power to help prevent an abundance of electrical current, fires, or shocks. 

Hire Professional Property Inspectors

An evaluation of the electrical panel is part of the evaluation that occurs during a home inspection. You can hire professional home inspectors to inspect them and make recommendations. During your real estate transaction, hire Dwell Inspect Arizona for home inspection and consulting services for homeowners in Phoenix and the surrounding regions. Call us at (480) 867-4599 to schedule your home inspection. Peace of mind awaits.