What is an electrical panel?
The electrical panel is the main component of an electrical distribution system that divides electrical power to the branch circuits while providing protection devices for each circuit in a common enclosure.
In essence, electrical panels are used to protect against electrical overloads and short circuits while distributing electricity throughout a building or facility.
The National Electrical Code® (NEC®) defines an electrical panel as a single panel or group of panel units designed for assembly in the form of a single panel; including buses, automatic overcurrent devices, and equipped with or without switches for the control of light, heat, or power circuits; designed to be placed in a cabinet or cutout box placed in or against a wall or partition and accessible only from the front
According to the NEC® definition, electrical panels are:
- Used to control light, heat, or power circuits
- Placed in a cabinet or cutout box
- Mounted in or against a wall
- Accessible only from the front
Other definitions of the electrical panel:
- Panelboard
- Distribution board
- Electrical switchboard
Electrical panel types
Electrical panels are often categorized by their general application, whether they are used for lighting and appliances or used for power. There are 4 types of panels available: Lighting electrical panels, power electrical panels, switchboards, low voltage switchgear.
Lighting electrical panels
Lighting and appliance electrical panels contain overcurrent protection and a means to disconnect lighting, appliances, receptacles, and other small load circuits. All other electrical panels are used for power and may also feed other panels, motors, and transformers in the building’s or site’s overall power distribution systems.
Power electrical panels
Power electrical panels are generally used in industrial facilities and new or retrofit commercial construction applications where the electrical distribution needs are more complex and require system-level solutions. These electrical panels offer broad system application capability for service entrance requirements or general power circuit distribution. For example, multi-tenant use facilities commonly employ power panelboards for electrical distribution. Increasingly, power electrical panels are specifically designed to meet applications where changes and additions must be fast, convenient, and easy.
Today’s innovative power electrical boards enable facilities to achieve reliable power performance at optimal energy-efficiency levels within the smallest footprint possible. The primary benefits of power electrical panels are their ability to accommodate wider ranges of volts AC while housing more breakers in less space. Both circuit breakers and fusible switches can be included in a single, bolt-on chassis design. A variety of special power electrical panel features enable facility managers to coordinate power distribution selectively, meter and monitor power usage closely and remotely, and ensure personnel safety with arc flash and fault protection options.
Switchboards
For larger-scale buildings or sites, a large single panel, frame, or assembly of panels can be used for mounting the overcurrent switches and protective devices, buses, and other equipment. These floor-mounted, freestanding solutions are known as switchboards.
Switchboards are most often accessible from the front, mounted on the floor, and close to the wall. Switchboards function the same as panelboards (and often simply feed other panelboards), but on a larger scale and at the low voltage of 600 Vac or less. They are used to divide large blocks of electrical current into smaller blocks used by electrical devices. This division helps distribute power to loads; disconnecting loads for safer maintenance; and protecting conductors and equipment against excess current due to overloads, short circuits, and ground faults.
Generally, switchgear should be considered whenever the highest degree of power reliability is desired. It is especially appropriate for critical power applications—those that are so important to a user’s enterprise that they cannot sustain a loss of power without incurring a harmful loss of revenue, production, or human safety.
Electrical devices inside the electrical panel
Although it varies according to the type of panel, when you open a panel door you are likely to see the following elements:
- Circuit breakers
- Disconnectors
- Contactors
- Miniature circuit breakers
- Surge protection devices
- Terminal blocks
- Residual current devices
- Cable ferrules, cable ducts, cable ties
- Cables
- Motor protection devices
- Thermal overload relays
- Relays
- PLCs
- Power supplies
- HMI
- Pilot devices
- Power capacitors
- Measurement and display devices mounted on the panel cover
- Current and voltage transformers
- Limit switches
- Panel heaters
- Panel fans
- Thermostats
