Eaton 3MM312RRL Meter Stack - UL Listed Group Metering
Part Number: 3MM312RRL
Quick Summary
Eaton residential meter stack enables compact three-phase metering for multi-tenant facilities and light commercial applications. By consolidating five jaws and three sockets into a single assembly, it reduces panel footprint while preserving reliable service separation. Many projects struggle with space, wiring complexity, and security in shared electrical spaces; this module addresses those challenges with ringless security and a no-bypass design. The unit is UL Listed and designed for indoor/outdoor use, backed by broad utility approvals across ME, NC, VA, AR, and TX to support field deployment. With 120/208V operation and an aluminum bus rated at 800 A, it delivers scalable, code-compliant metering that streamlines procurement and installation. This translates to faster commissioning and lower lifecycle costs for utilities and property owners.
Product Information
Extended Description
3MM312RRL Eaton: Eaton's Three-Phase Residential Meter Stack Module, Group Metering Type, 125A, Aluminum Bus 800 Ampere, No bypass, Indoor/outdoor, Five-jaws, 3 Sockets, Three-phase in, single-phase out, Ringless Security, 120/208V
Product Name
Eaton residential meter stack
Catalog Number
3MM312RRL
UPC
786849052140
Product Length/Depth
40 in
Product Height
8 in
Product Width
15 in
Product Weight
51 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
Type
Group Metering
Utility approvals
ME : Central Maine Power NC : Dominion VA : Dominion ME : Emera Maine (Bangor Hydro Electric Co./ Maine Public Service Company) AR : Entergy LA : Entergy MS : Entergy TX : Entergy GA : Georgia Power KS : Kansas City Power and Light (KCPL) / Westar Energy MO : Kansas City Power and Light (KCPL) / Westar Energy TN : Middle Tennessee EMC FL : Tallahassee City Electric SC : South Carolina Electric and Gas (SCE&G) IN : Indiana Michigan Power (IMP) (AEP East) MI : Indiana Michigan Power (IMP) (AEP East) OH : AEP Ohio (AEP East) TN : Appalachian Power (AEP East) VA : Appalachian Power (AEP East) WV : Appalachian Power (AEP East) TX : Texas-New Mexico Power (TNMP) NM : Texas-New Mexico Power (TNMP)
Interrupt rating
Depends on selected main circuit breaker
Enclosure
Indoor/outdoor
Secondary circuit breaker
BR2_, BRH2_, BRHH2_
Bus Rating
800 A
Phase
Three-phase in, single-phase out
Voltage rating
120/208V
Amperage Rating
125A
Bus material
Aluminum
Bypass
None
Number of jaws
Five-jaw
Number of sockets
3
Phase balance
A-B
Security
Ringless
Residential and Light Commercial, Metering Products, Volume 1 Tab 4
Eaton Specification Sheet - 3MM312RRL
Feature → Business Impact → Application: Three-phase in, single-phase out with a 125A rating and an 800 A bus rating provides a scalable foundation for feeders in multi-tenant buildings, reducing wiring complexity and panel space while maintaining safety margins. This enables faster panel layouts and easier future upgrades in busy utility rooms or shared electrical closets. Feature → Business Impact → Application: Aluminum bus construction lowers weight and improves corrosion resistance, cutting installation time and labor costs while supporting longer service life in challenging environments. It is ideal for indoor/outdoor installations in warehouses, residential campuses, and light commercial sites. Feature → Business Impact → Application: Five-jaw input with three sockets supports organized, tamper-resistant metering with clear separation of circuits, enhancing security and compliance for shared metering scenarios. Feature → Business Impact → Application: Ringless security and no bypass design reduce tampering risk and simplify code compliance audits for property managers and contractors. Feature → Business Impact → Application: UL Listed certification and broad utility approvals ease regulatory acceptance, expedite permit processing, and minimize project risk across a range of markets. Feature → Business Impact → Application: Compatibility with common secondary breakers BR2_, BRH2_, BRHH2_ enables flexible modernization paths without replacing the entire enclosure, supporting retrofits and upgrade projects. Warranty and service support: Eaton’s 25-000 policy offers a one-year warranty from installation or eighteen months from shipment, giving owners predictable maintenance costs and a clear disposition for field service.
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FAQs
The 3MM312RRL is designed for three-phase in, single-phase out service with five-jaw input and three sockets. Use compatible secondary breakers BR2_, BRH2_, or BRHH2_ as specified by Eaton. Plan for indoor/outdoor enclosure placement, ensure correct voltage (120/208V), and follow Eaton’s installation instructions to maintain ringless security and code compliance. This approach minimizes wiring conflicts and speeds up commissioning in shared meter rooms.
Its group metering design consolidates metering points, reducing cabinet footprint while preserving individual service separation. The five-jaw input, three sockets, and 125A rating support scalable feeders, and the aluminum bus enables lighter installations. Ringless security and no bypass features improve tamper resistance, helping property managers meet regulatory requirements across multiple tenants and streamline utility billing.
Yes, the unit is UL Listed, which signifies compliance with recognized safety standards for electrical equipment. This certification supports safer installations, simplifies permitting, and enhances reliability in both new builds and retrofit projects. The inverter-free, no-bypass design further reduces risk, contributing to compliant metering installations in accordance with local codes and utility expectations.
The product carries broad utility approvals across multiple jurisdictions, including Maine, North Carolina, Virginia, and Texas, among others. These approvals facilitate faster permit approvals and smoother interconnection processes for utilities and developers, enabling standardized metering across campuses, multi-dwelling units, and commercial properties with fewer site-specific restrictions.
Choose an indoor/outdoor rated enclosure to suit site conditions and plan for a 40 in by 15 in by 8 in footprint with a 51 lb weight. The 125A rating and 800A bus support scalable growth, while ringless security reduces tampering risk. The no-bypass design minimizes service interruptions, and the UL Listed certification simplifies compliance and reduces audit time, contributing to lower total cost of ownership.