Evenson Power UL 891 switchboards deliver dependable, dead-front low-voltage power distribution and overcurrent protection for service-entrance and main-distribution duty.
The Evenson Power Switchboard is the central low-voltage distribution asset that takes incoming power from a service transformer or generator and divides it into protected feeder circuits for the rest of a facility. Built to UL 891 — the North American standard for low-voltage switchboards rated 1000 V AC and below — it combines a main overcurrent device, a heavy-duty bus system and a bank of feeder breakers inside a single dead-front enclosure, giving facilities a safe, code-compliant single point of control and protection.
Engineered and labeled under the Evenson Power name, each switchboard is configured to the specific voltage, amperage, fault current and feeder schedule of the installation. From an 800 A commercial main to a 6,000 A service entrance feeding a data center or mining hall, the platform scales to demanding continuous-duty applications while remaining straightforward to install, operate and maintain.
A UL 891 switchboard is a free-standing, dead-front assembly that receives bulk electrical power and distributes it to downstream panelboards, motor control centers and equipment. “Dead-front” means there are no exposed energized parts on the operating face — operators interact only with insulated breaker handles and covers, which dramatically improves safety during normal switching and inspection.
UL 891 governs low-voltage boards at 1000 V AC or less and is the workhorse standard for service-entrance and main distribution in North America. Compared with UL 1558 industrial switchgear, UL 891 boards use group-mounted (fixed) breakers and a more compact, cost-effective construction, making them the practical choice for the great majority of commercial, institutional and light-industrial power distribution.
Evenson Power switchboards are built on a rigid steel frame with bolted, formed-steel panels and a sectionalized layout that allows multiple vertical sections to be shipped, rigged and bolted together on site. Standard indoor units are supplied in a NEMA 1 enclosure; outdoor and harsh-environment installations use a weatherproof NEMA 3R enclosure with gasketed doors and drip hoods.
Free-standing sections sit on floor channels and are front-accessible for breaker maintenance, with the service entrance arranged for top, bottom or side incoming feed as required. A typical board is a minimum of 32 inches wide and 32 inches deep and stands 72 to 84 inches tall, with generous, code-mandated wire-bending space at every breaker terminal so conductors can be landed safely and without strain.
At the heart of every board is a high-conductivity copper (or optional aluminum) through-bus that runs the length of the lineup and carries the main current to each section. Bus is rated from 800 A up to 6,000 A and braced to withstand the mechanical forces of a short-circuit event up to the board’s full interrupting rating. Tin- or silver-plated joints keep connections cool and stable over decades of continuous loading.
The main device is a service-entrance-rated breaker (commonly a UL 1066 power circuit breaker) that provides the single-point system shutoff. Feeder protection is provided by group-mounted UL 489 molded-case breakers that tap directly off the through-bus to supply individual loads. Three-phase, four-wire (with neutral) and three-phase, three-wire configurations are both supported, with a full-size neutral and a continuous ground bus.
Evenson Power switchboards are offered across the standard low-voltage range, with system voltages of 208 V, 240 V, 480 V and 600 V and a main bus selectable from 800 A through 6,000 A in common steps of 1,200, 2,000, 2,500 and 4,000 A. Interrupting ratings are matched to the available fault current at the service, up to a 100 kAIC withstand with a three-cycle short-time rating.
Each board is built to order from the engineer’s specification: system voltage and wiring, main bus ampacity, the count and rating of feeder breakers, indoor or outdoor duty, interrupting rating, preferred breaker manufacturer, service-entrance location and any special features. This made-to-order approach ensures the delivered board matches the one-line drawing and the physical constraints of the electrical room exactly.
Because they combine high capacity, safe dead-front operation and flexible feeder arrangements, Evenson Power switchboards serve as the main distribution backbone across a wide range of facilities. They are equally at home as a building service entrance, a sub-distribution board on a large campus, or the primary distribution point inside a high-density computing environment.
Every Evenson Power switchboard is assembled under a controlled quality system and verified before it ships. Boards are evaluated for thermal performance under rated continuous load, for short-circuit withstand of the bus and bracing, and for dielectric integrity, with operational checks of every main and feeder device. Construction follows UL 891 with full NEC (NFPA 70) compliance and alignment to Canadian Electrical Code Part I.
Each board is supplied with a nameplate stating its ratings, a complete as-built one-line and dimensional drawings, breaker schedules and torque specifications for field connections. Witnessed factory testing and third-party inspection can be arranged on request, and the documentation package gives the installing contractor and the authority having jurisdiction full traceability.
A broad menu of options lets each board be tailored to the project. Integrated power metering, surge protective devices, ground-fault detection, and current and voltage transformers support monitoring and protection, while HMI displays, shunt-trip provisions and generator tie-ins add control and resilience. Boards can also be specified with K-factor and harmonic-mitigation provisions for non-linear loads such as drives and IT power supplies.
To configure a switchboard, supply the system voltage and wiring configuration, the main bus ampacity, the feeder breaker count and ratings, indoor or outdoor use, the required interrupting rating, any preferred breaker manufacturer, and the service-entrance location. The Evenson Power technical team reviews the one-line and electrical-room constraints, returns a submittal drawing for approval, and manufactures the board to match.
Because switchboards are made to order, lead time and pricing are confirmed per project. Contact Evenson Power with your specification or one-line drawing for a tailored quotation, submittal support and delivery scheduling.
| Standard | UL 891 (low-voltage switchboard) |
| Compliance | NEC / NFPA 70, Canadian Electrical Code Part I |
| System voltage | 208 / 240 / 480 / 600 V AC (≤ 1000 V) |
| Main bus rating | 800 A – 6,000 A (1200 / 2000 / 2500 / 4000 A common) |
| Interrupting rating | Up to 100 kAIC, 3-cycle short-time withstand |
| Configuration | 3-phase 4-wire (with neutral) or 3-phase 3-wire |
| Bus material | Copper (standard) or aluminum, plated joints |
| Main device | Service-entrance UL 1066 power circuit breaker |
| Feeder devices | Group-mounted UL 489 molded-case breakers |
| Construction | Dead-front, free-standing, sectionalized steel |
| Enclosure | NEMA 1 (indoor) / NEMA 3R (outdoor) |
| Service entrance | Top, bottom or side incoming feed |
| Minimum dimensions | 32" W × 32" D × 72–84" H |
| Frequency | 60 Hz |
| Options | Metering, SPD, GFD, CT/VT, HMI, shunt-trip, gen tie-in |
Engineered, certified and delivered under the Evenson Power name.
