Cummins RS125 125kW QuietConnect Standby Generator — 120/240V 1-Phase — A063B604
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At a glance
- Standby Power
- 125 kW
- Voltage / Phase
- 120/240V, Single-Phase (60 Hz)
- Fuel
- Natural Gas or LP (field-selectable dual fuel)
- Engine
- Cummins 8.9L turbocharged, aftercooled inline 6-cylinder, 1800 RPM
- Cooling
- Liquid-cooled
- Sound Level
- 75 dBA (Level 1 enclosure)
- Dimensions
- 143"L x 40"W x 72"H
- Weight
- 3,915 lbs
- Voltage Regulation
- +/-1%
- Warranty
- 2-year base warranty (extended options available)
Why this generator
- Heavy-duty 125 kW output from a liquid-cooled Cummins 8.9L inline-6 engine — serious whole-home and light-commercial backup power
- Field-selectable dual fuel runs on either natural gas or LP, so you can match whatever fuel supply your property has
- Quiet 75 dBA operation thanks to an advanced acoustic aluminum enclosure — among the quietest in its class
- Powder-coated aluminum enclosure withstands hurricane-force winds up to 180 MPH (ASCE 7-10)
- Reliable cold-weather starting down to -40 degrees F for dependable backup in extreme climates
- PowerCommand electronic control with flexible exercise mode — self-test for as little as 2 minutes every 6 months
Everything you need to know
The Cummins C125N6 is a 125 kW natural gas or LP standby generator from the Cummins QuietConnect commercial-grade series — a liquid-cooled machine built to carry commercial buildings, agricultural and industrial sites, and multi-building properties through extended utility outages. Permanently connected to your natural gas or propane supply, it runs as long as fuel flows, with no refueling and no tanks to monitor.
Automatic, Hands-Off Backup
Paired with a Cummins automatic transfer switch, the C125N6 monitors utility power continuously, starts within seconds of an outage, and transfers the full load automatically — then returns to utility power and shuts down once the grid is restored. No manual switching, no cords, and no downtime for the systems that can't go dark.
Commercial-Grade Power & Control
Cummins PowerCommand control governs the C125N6 with precise voltage and frequency regulation and strong motor-starting capability — critical for hard-starting loads like central air conditioning, well and irrigation pumps, refrigeration, and three-phase equipment. It's the same power pedigree Cummins builds for hospitals, data centers, and critical facilities, scaled for commercial and industrial use.
Natural Gas or Propane — Continuous Runtime
Connected to a utility natural-gas line, the C125N6 runs continuously through even multi-day outages with no refueling. On LP it draws from your on-site propane tank. Either way you get clean, continuous power without the fuel logistics of diesel, ideal anywhere a gas line is available.
Factory-Authorized, Quote-Based Pricing
Total Generator Pros is a factory-authorized Cummins dealer. Because every large-format standby installation is engineered to the site, pricing on the C125N6 is quote-based. Request a free quote and we'll spec the unit, transfer switch, and installation for your project — with free nationwide shipping, turnkey installation across North & South Carolina, and 0% APR financing available on qualifying orders.
- 125 kW standby power
- Cummins QuietConnect series, liquid-cooled
- Natural gas or LP (propane) fuel
- Cummins PowerCommand digital control
- Automatic whole-building transfer with a Cummins ATS
- Commercial-grade, engineered for commercial and industrial use
- Model C125N6
Frequently asked questions
What fuel does the A063B604 run on?+
The A063B604 runs on natural gas or LP (propane), selectable at install.
Does the price include installation?+
No — the online price covers the unit shipped free to the lower 48. Professional installation is available in NC & SC on a quote basis; outside that area we'll help you find a qualified local installer.
How fast does it ship?+
Free curbside / liftgate shipping to the contiguous 48 states. Made-to-order units typically ship in 12 weeks or less.
What warranty is included?+
5-year limited factory warranty, registered and supported directly through Cummins.
Is financing available?+
Yes — 0% APR financing is available on qualifying orders. Ask us for details before checkout.
Free curbside shipping
Liftgate delivery to the lower 48. Ships in 12 weeks or less (made-to-order commercial unit).
Install help, no upsell
We size, spec, and connect you with a vetted local installer — or talk your contractor through it for free.
Real Cummins warranty
Full 5-year limited warranty — registered and supported through Cummins directly.