Eaton 3MTB400RC Main Terminal Box - UL Listed, NEMA 3R
Part Number: 3MTB400RC
Quick Summary
Eaton 3MTB400RC main terminal box provides reliable 400A terminations for three-phase, 120/208 V systems. The design minimizes lug crowding and secure landings, reducing field rework and downtime. UL Listed, NEMA 3R enclosure, and utility approvals from ConEd and NorthWestern Energy reinforce compliance across regions. Copper bus and top/bottom feed enable flexible installation while compatible lug landing kits and accessories help optimize project timelines and overall reliability for critical power distribution.
Product Information
Extended Description
3MTB400RC Eaton: Eaton main terminal box, 400A, Copper, NEMA 3R, Overhead/underground, Four-wire, Three-phase, 120/208V, (1) #6 AWG-600 kcmil, (2) #1/0 AWG-250 kcmil
Product Name
Eaton main terminal box
Catalog Number
3MTB400RC
UPC
782114556139
Product Length/Depth
6.5 in
Product Height
8 in
Product Width
13.5 in
Product Weight
54 lb
Warranty
Eaton Selling Policy 25-000, one (1) year from the date of installation of the Product or eighteen (18) months from the date of shipment of the Product, whichever occurs first.
Certifications
UL Listed
Catalog Notes
For compression lug landing kits, order 3MTB1200CLK (includes landings for 3-phases and neutral).
Amperage Rating
400A
Bus material
Copper
Feed type
Top/bottom
Phase
Three-phase
Voltage rating
120/208 V
Wire size
(1) #6 AWG-600 kcmil, (2) #1/0 AWG-250 kcmil
Utility approvals
NY : Consolidated Edison (ConEd) MT : NorthWestern Energy NE : NorthWestern Energy SD : NorthWestern Energy WY : NorthWestern Energy
Enclosure
NEMA 3R
Number of wires
4
Residential and Light Commercial, Metering Products, Volume 1 Tab 4
Eaton Specification Sheet - 3MTB400RC
Feature: 400A amperage rating → Business impact: Supports heavy-load three-phase feeders with margin for future expansion, reducing rack changes and replacements. Application: Ideal for main feeder terminations in commercial/industrial panels. Feature: Copper bus material → Business impact: Provides superior conductivity and thermal performance, lowering voltage drop and heat buildup in long runs. Application: High-current distribution in compact spaces with minimal voltage loss. Feature: NEMA 3R enclosure → Business impact: Delivers weather-resistant protection for indoor or outdoor mounting, improving uptime in challenging environments. Application: Outdoor meter/feeder installations and covered exterior panelboards. Feature: Top/bottom feed → Business impact: Flexible wiring and landings simplify installation, reducing labor time and errors. Application: Varied mounting orientations in retrofit and new builds. Feature: Four-wire, three-phase configuration → Business impact: Delivers a complete power distribution solution with neutral capability, ensuring compliance with standard electrical codes. Application: Industrial plants and commercial facilities with 120/208 V systems. Feature: Catalog notes and compatibility → Business impact: Ready integration with compression lug landing kits (3MTB1200CLK) streamlines project planning and supply chain management. Application: Faster field upgrades and standardized assemblies.
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FAQs
The 3MTB400RC installs with top/bottom feed and accommodates a four‑wire, three‑phase configuration at 120/208 V. Use the copper bus for low resistance terminations and landings sized from #6 AWG to 600 kcmil (with #1/0 AWG to 250 kcmil on the auxiliary). Ensure enclosure is mounted per NEMA 3R guidelines and verify UL Listed compliance in your panel assembly.
Key specs include a 400A amperage rating, copper bus material, four conductors, three-phase configuration, 120/208 V, NEMA 3R enclosure, and UL Listed certification. It supports large wire landings (1/6 AWG–600 kcmil and 2/0–250 kcmil ranges) for flexible and robust power distribution in demanding environments.
Yes. The 3MTB400RC is designed for overhead/underground applications with a four-wire, three-phase feed. Its NEMA 3R enclosure and copper bus are optimized for both indoor and outdoor use, offering reliable performance in utility-driven and industrial power distribution scenarios.
This product is UL Listed and enclosed in a NEMA 3R rating, ensuring safety and environmental protection. Utility approvals (ConEd and NorthWestern Energy) further support project compliance in multiple regions, reducing the need for alternative certification demonstrations during procurement and commissioning.
With a 400A copper bus and durable NEMA 3R enclosure, maintenance intervals are extended and rework is minimized. The option to use lug landing kits (3MTB1200CLK) simplifies future expansions or reconfigurations, lowering total cost of ownership by reducing field labor and downtime during upgrades or re-terminations.