Overview#
The Cummins C400 N6 is a 400-kilowatt natural gas standby generator — the largest model in the C-Series commercial gaseous lineup. Built on the GTA28E, a 28-liter (1,709 in³) turbocharged inline-6 spark-ignited engine, the C400 N6 delivers substantial standby capacity for large hospitals, commercial campuses, industrial facilities, and mission-critical installations that prefer gaseous fuel over on-site diesel storage.
The C400 N6 is listed to UL 2200 in open-set, weather-protective, and sound-attenuated enclosure configurations, and is certified to EPA SI NSPS Stationary Emergency standards (40 CFR 60 Subpart JJJJ). The generator accepts 100% rated load in a single step per NFPA 110 Type 10 (ten-second transfer) for Level 1 and Level 2 EPSSs.
The PowerCommand 3.3 control supports full paralleling functionality — including Phase Lock Loop synchronization, isochronous kW/kVar load sharing, extended paralleling for baseload/peak-shave operation, and 20 configurable inputs/outputs. Multi-unit arrays with N+1 redundancy are a common C400 N6 deployment at large commercial and institutional facilities.
Generator dimensions (all models): 4,216 mm x 2,083 mm x 2,486 mm (166 x 82 x 98 in.).
Technical Specifications#
| Parameter | Value |
|---|---|
| Standby Rating | 400 kW (500 kVA) |
| Frequency | 60 Hz |
| Power Factor | 0.8 |
| Engine Model | GTA28E |
| Displacement | 28 L (1,709 in³) |
| Configuration | Inline-6, wet cylinder liners |
| Aspiration | Turbocharged |
| Rated Speed | 1800 rpm |
| Starting System | 24 VDC, dual 8D, 1400 CCA |
| Battery Charging Alternator | 43 amps |
| Lube Oil Filter | 3x spin-on canister, full flow with bypass |
| Control | PowerCommand 3.3 |
| Dimensions (L x W x H) | 4216 x 2083 x 2486 mm (166 x 82 x 98 in.) |
Natural gas fuel consumption (SCFH):
| Load | SCFH |
|---|---|
| 25% | 2,477 |
| 50% | 3,490 |
| 75% | 4,645 |
| 100% | 5,946 |
Fuel inlet pressure: 254 to 508 mm WC (10 to 20 in. WC) at the fuel shut-off valve under full load. Maximum supply pressure: 635 mm WC (25 in. WC).
Available voltage configurations (three-phase): 120/208V, 127/220V, 139/240V, 220/380V, 240/416V, 254/440V, 277/480V, 347/600V
Full-load amperage at 277/480V (3-phase, 0.8 PF): 601 amps
Our Service Experience#
The C400 N6 is our go-to recommendation for large commercial and institutional accounts that have a strong preference for gaseous fuel. At 400 kW, the turbocharged GTA28E runs hard under full-load test conditions — thorough load bank testing at commissioning and annually is essential to verify performance. The GTA28E's larger wet-liner block design is more durable than smaller gaseous engines but the fuel pressure requirements are more stringent (10-20 in. WC vs. 6-13 in. WC for the smaller N6 models).
Our annual service program for C400 N6 installations covers:
- Gas supply pressure verification under full load (critical — underpressure causes performance degradation)
- Turbocharger inspection for bearing wear, oil sealing, and shaft play
- Spark plug replacement at 1,500-hour intervals
- Charge air cooler inspection
- Full load bank test at or near rated output
- PowerCommand 3.3 fault history review via InPower service tool
Frequently Asked Questions#
What engine does the C400 N6 use? The Cummins GTA28E — a turbocharged 28-liter (1,709 in³) inline-6 spark-ignited engine with replaceable wet cylinder liners, 24V starting at 1,400 CCA, and a 43-amp battery charging alternator. Three spin-on oil filter canisters (combination full flow with bypass).
What is the fuel consumption of the C400 N6 at full load on natural gas? At 100% standby load: 5,946 SCFH. At 75%: 4,645 SCFH. At 50%: 3,490 SCFH. At 25%: 2,477 SCFH. Fuel inlet pressure at the fuel shut-off valve under full load must be 254 to 508 mm WC (10 to 20 in. WC).
What is the largest Cummins C-Series gaseous generator? The C400 N6 is the top of the C-Series commercial gaseous lineup at 400 kW. For loads beyond 400 kW on natural gas, facilities typically parallel multiple C400 N6 units with PowerCommand controllers, or move to Cummins' industrial gaseous platforms.
Is the C400 N6 approved for NFPA 110 Level 1 healthcare standby? The C400 N6 is UL 2200 listed and meets NFPA 110 Type 10 (ten-second transfer) Level 1 performance requirements when properly installed. Healthcare applications require AHJ confirmation. Natural gas dependency is a key risk factor — many healthcare codes mandate diesel for primary life-safety coverage.
How does paralleling C400 N6 units compare to a single large diesel? Paralleling multiple C400 N6 units provides N+1 redundancy, scalability, and gaseous-fuel operational benefits. The trade-off is increased switchgear complexity and dependency on continuous gas supply. The PowerCommand 3.3 control supports First Start Sensor, Phase Lock Loop synchronization, and isochronous kW/kVar load sharing for reliable multi-unit operation.
