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Panelboards are used to safely distribute electricity throughout commercial and industrial facilities. A panelboard is a component of an electrical distribution system which divides an electrical power feed into branch circuits, while providing a protective circuit breaker or fuse for each circuit, in a common enclosure. A panelboard services to protect branch circuits from overloads and short circuits. Panelboards are designed to meet UL 67 and NEMA Standard PB1.
Switchboards and panelboards provide a similar functionality in a power distribution system. Panelboards are typically flush mounted or surface mounted and are limited to a maximum of 1,200 A incoming current (main). Switchboards are free-standing units that are front connected and, like panelboards, require only front access.
However, switchboards can allow for both front and rear access if desired. Switchboards can accommodate up to 6000 A bussing and overcurrent protective devices up to 5000 A. Where panelboards are designed to UL 67, switchboards are governed by UL 891.
A load center (i.e., breaker box, fuse box) takes electricity from the utility source and distributes it throughout a facility to support reliable electrical distribution.
The distribution of power to the various circuits is protected from over-current by the use of circuit breakers or fuses.
Once you open the door to the panel you can access all the circuit breakers or fuses. Usually one of these panels distributed power to all of the circuits within a home or facility, but there may be a situation where another "sub-panel" is utilized to support a dedicated region within a building.
A load center provides similar functionality in a power distribution system as a switchboard and a panelboard. As far as UL and the NEC standards are concerned, there is no difference between a panelboard and a load center. In North America, the electrical industry refers to smaller, lower cost panelboards sold primarily in residential applications as load centers. Panelboards are typically deeper than load centers and can accommodate both bolt-on circuit breakers as well as plug-in breakers, whereas a load center is limited to plug-in breakers.
Load centers are also limited to 240 V or less and typically are provided at 100 A or less, with a maximum current rating of up to 400 A. Panelboards can be applied at up to 600V and with a maximum current rating of 1,200 A. Load centers are typically offered with no or minimal options where panelboards can be provided with various optional features including main and branch circuit energy monitoring, and integrated surge suppression devices.
Eaton offers general purpose panelboards for both circuit breaker (Pow-R-Line 1X, 2X, 3X) and fusible switch (Pow-R-Line 1XF, 2XF) applications.
The choice of specific panelboard is dependent on:
Hazardous rated panelboards are for use in areas where flammable gases and vapors or combustible dusts may be present. Selecting the appropriate hazardous area panelboard is dependent on:
Hazardous rated panelboards are available with the following NEC hazardous area certifications:
Panelboards are constructed, and typically shipped, as three separate primary components.
The five-sided enclosure itself, commonly called the ‘can’ or ‘box’ is typically made of galvanized steel and is either flush mounted or wall mounted.
Eaton’s EZ-trim incorporates a unique, one-piece design that allows the trim to be installed in seconds with no additional hardware or tools.
To match the construction process, the panelboard cans are typically shipped first, followed by the interiors and the trims.
In addition to these primarily components, panelboards also include a label that provides information regarding the unit’s electrical ratings and manufacturing date, filler plates used to cover any unused spaces, and a circuit directory card located on the inside of the door. Get your blank panelboard circuit directory template.
The branch devices in a panelboard provide overcurrent protection for downstream devices. Most often both functions are provided by a molded case circuit breaker. However, fusible switches can also be provided.
Eaton’s panelboards are built around Eaton’s Power Defense circuit breaker technology and Bussmann Series fuse technology.
Panelboards can be supplied with electronic metering devices to monitor both incoming power to the panel as well as the power distributed through individual branch devices.
These meters can communicate, via common industry protocols, as part of an overall building energy management system. They can aid in complying with local energy codes or be part of your overall IoT/Industry 4.0 strategy.
Voltage spikes and surges can find their way into your facility from an outside disturbance or can manifest itself from equipment within your facility. Surge protection devices (SPDs) protect sensitive downstream electronic devices from the damaging effects of voltage surges or spikes.
Panelboard mounted SPDs can either be side-mounted or integrated design. Side-mounted units come pre-wired in a separate enclosure and are field-mounted and wired to the panel in the field.
Integrated Surge Protection Devices, like Eaton’s SPD Series, are factory mounted directly to the panelboard chassis. In addition to time and space savings, an integrated SPD increases system protection by reducing let-through voltage due to the zero-lead length design.
Learn about the many advantages of integrating surge protection inside power distribution equipment.
Panelboards, as well as other power distribution assemblies like switchboards and switchgear, carry a short-circuit current rating that defines the amount of fault current that the equipment is designed to withstand. There are three protection systems used to protect low voltage power distribution systems. They are:
Fully rated protection — where all overcurrent devices are rated for the full prospective short-circuit current at their line side terminals throughout the system. In a fully rated system, the short-circuit current rating of the panelboard is determined by the short-circuit current rating of the lowest rated overcurrent device in the panelboard
Selectively coordinated protection — A fully rated system where the overcurrent device closest to the fault will open first, thus isolating the faulty circuit.
Series rated protection — A short-circuit interrupting rating assigned to a combination of two or more overcurrent protective devices that are connected in series and in which the rating of the downstream device(s) in the combination is less than the series rating. Series ratings are also known in the industry as integrated ratings, series combination ratings and series connected ratings.
In a series rated system, the overcurrent devices in series in the protective scheme must have been tested and listed by Underwriters Laboratories (UL), for series combination use in the system.
Eaton’s currently published series ratings can be found in the current version of the panelboard and switchboard series rating information manual.
The Eaton Power Systems Experience Center (PSEC) has partnered with the University of Pittsburgh, IBEW Local 5, NJATC and other programs where students benefit from visual learning. See what engineers, consultants, and electricians learn at PSEC.
At Eaton's Power Systems Experience Center (PSEC), see Power Defense circuit breakers in action and learn how to monitor system faults, diagnose power quality issues, and measure reliability with breaker health.
Our manufacturing centers across the U.S. deliver customized solutions, local market expertise, shortened lead times and 24/7 disaster response—so you can keep projects on-time and on-budget.
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