Eaton 800A Main Fusible Switch...
IN STOCK (leaves warehouse same day if ordered before 3pm ET)
$7,298.30
Eaton 800A Main Fusible Switch, Aluminum, NEMA 3R

Eaton 800A Main Fusible Switch, Aluminum, NEMA 3R

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Model: 3MFS800RB

In Stock (leaves warehouse same day if ordered before 3pm ET)

$7,298.30
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Eaton 800A Main Fusible Switch, Aluminum, NEMA 3R

The Eaton 800A Main Fusible Switch is a three-phase, aluminum-bus service entrance switch engineered for underground utility installations. Rated 120/208V with an 800A amperage rating and a 100 kAIC interrupt rating, this switch accepts Class T and Class L fuses and is housed in a NEMA 3R enclosure for outdoor and wet-location protection. It is UL Listed and built for reliable, code-compliant power distribution in commercial and multi-family metering applications.

Key Features

  • Amperage Rating: 800A three-phase switch rated 120/208V for main service disconnect applications.
  • Durable Construction: Aluminum bus bar construction delivers reliable current-carrying performance.
  • Fuse Clip Type: Class T fuse clips are field-convertible to Class L by simply repositioning — no conversion kit is needed.
  • Interrupt Rating: 100 kAIC interrupt rating supports high fault-current utility service applications.
  • Feed Type: Bottom feed configuration suited for underground service entrance wiring.
  • Wire Size: Accepts (4) #3/0 AWG-750 kcmil conductors across 4 wire positions.
  • Enclosure: NEMA 3R enclosure rated for outdoor and underground installations.
  • Dimensions: 20.17 in wide x 17.09 in deep x 47.7 in high, sized for accurate panel and pad placement.

Certifications & Compliance

  • UL Listed
  • NEMA 3R Rated Enclosure
  • Utility Approved: NC - Dominion

Technical Specifications

  • Number of wires: 4
  • Department: Electrical

Typical Applications

  • Underground Utility Service Entrances
  • Multiple Metering and Commercial Distribution Equipment
  • Outdoor and Wet-Location Installations
  • Panelboard and Load Center Main Disconnects
  • New Construction and Utility Service Upgrades

Why Eaton?

Eaton backs this main fusible switch with UL Listed certification, an aluminum bus, and a 100 kAIC interrupt rating for demanding underground service applications. Field-convertible Class T to Class L fuse clips simplify inventory and installation, while the NEMA 3R enclosure ensures dependable performance in outdoor environments. Eaton's engineering and utility approvals help ensure code-compliant, reliable power distribution for professional electrical installations.

Manufacturer Resources

Product Specs

Product Width:
20.17 in
Voltage Rating:
120/208V
Amperage Rating:
800A
Product Length/Depth:
17.09 in
Fuse clip type:
Class T, Class L
Product Height:
47.7 in
Phase:
Three-phase
Feed type:
Bottom
Interrupt rating:
100 kAIC
Bus material:
Aluminum
Wire Size:
(4) #3/0 AWG-750 kcmil
Number of wires:
4
Utility approvals:
NC : Dominion
Configuration:
NEMA 3R Enclosure
Certifications:
UL Listed
Product Type:
Safety Switch
Department:
Electrical
Product Material:
Aluminum
Listing:
UL Listed
Product Group:
Power Distribution
Product Subgroup:
Safety Switches & Disconnects
Product Length:
17.09 in
Product Weight:
135 lb

Eaton 3MFS800RB – Frequently Asked Questions

1) Will the Eaton 3MFS800RB fusible switch take Class L fuses, or only Class T?
Both. The 3MFS800RB ships with Class T fuse clips that convert to Class L in the field by repositioning them, so no conversion kit is required. That matters if your engineer specs Class L current-limiting fuses for the 800A main but the switch arrives set up for Class T, you handle it on site.
2) What size service conductors will land in this 800A Eaton main switch?
The lugs take (4) #3/0 AWG through 750 kcmil conductors across four wire positions. That covers parallel sets on a typical 800A underground service. It is a three-phase switch rated 120/208V, so plan four wires: three phases plus neutral.
3) Is this Eaton main fusible switch top feed or bottom feed?
Bottom feed only. The 3MFS800RB is built for underground service entrance, with conductors coming up from the pad or duct bank into the bottom of the enclosure. If the utility is bringing service overhead to a weatherhead, this is the wrong configuration and you want a top-feed unit.
4) Can this 800A switch be mounted outdoors on a pad?
Yes. The enclosure is NEMA 3R, rated for outdoor and wet-location service, which is what underground utility service equipment normally requires. The cabinet measures 20.17 in wide by 17.09 in deep by 47.7 in high, so size the pad and the working clearance in front of it accordingly.
5) Does the Eaton 3MFS800RB have a high enough interrupting rating for a utility service with a big transformer?
It is rated 100 kAIC, which covers high available fault current at the service point on most commercial and multi-family 208Y/120 services. Compare that number to the available fault current the utility publishes for your transformer, and note the fuses themselves carry their own ratings.
6) Will the utility accept this switch for a service in North Carolina?
The 3MFS800RB carries a Dominion (NC) utility approval and is UL Listed. Utility approvals are territory-specific, so if you are outside Dominion's NC service area check the local utility's approved equipment list before ordering.
7) Can I use this as the main disconnect ahead of a multiple-metering stack?
That is one of its intended uses. As a three-phase 120/208V main service disconnect, the 800A fusible switch sits ahead of multiple metering equipment and commercial distribution gear, with the bottom-feed arrangement matched to underground service. It is service entrance equipment, not a downstream branch device.
8) What exact Eaton part number should I put on the purchase order for this 800A fusible switch?
Order Eaton model 3MFS800RB. That is the 800A, three-phase, 120/208V, bottom-feed main fusible switch in a NEMA 3R aluminum enclosure with 100 kAIC interrupting.
9) Do fuses come with the Eaton 800A main fusible switch?
The switch is supplied with fuse clips, not fuses. You specify and buy the Class T or Class L fuses separately to match your overcurrent study and the clip position you set. Since the clips convert between the two classes in the field, decide the fuse class before you order the fuses.
10) Is an aluminum bus a problem for an 800A main service switch?
No. The 3MFS800RB uses an aluminum bus, which is standard on utility service entrance equipment at this ampacity and is rated for the full 800A. The installation detail that matters is the terminations: use the correct listed compression or mechanical lugs for your conductor material and torque them to the markings in the cabinet.
How fast can I get the Eaton 3MFS800RB delivered?
Most orders ship the same day from our distribution partners, with quick delivery throughout the continental U.S. Need it urgently? Contact Us for expedited shipping options.
Can I return it if it doesn’t work for me?
Yes—ZenSupply offers a hassle-free return policy. If the product isn’t the right fit, reach out to our support team for a return authorization or setup a return by following our return instructions.
Does the Eaton 3MFS800RB come with a warranty?
Absolutely. The Eaton 3MFS800RB is backed by a manufacturer’s warranty. For full warranty terms, check the product documentation or Contact Us.
How do I get technical support or installation help for the Eaton 3MFS800RB?
You can call, text, or email our expert support team for fast answers. We’re here to help with product selection, installation tips, and troubleshooting. Contact Us
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