Generac · MG Series (Modular Gaseous)

Generac MG300

300 kW standby / 270 kW prime · Natural Gas / LPG · Liquid-cooled

300 kW modular natural gas standby generator system. Factory-paralleled for N+1 redundancy.

Standby power
300 kW / 270 kW prime
Voltage options
120/208V, 277/480V, 346/600V
Frequency / Phase
60 Hz · 3-phase
Engine
Generac 14.2L Inline-6 SI · 14.2L
Alternator
Generac K0300124Y21
CommercialManufacturingHealthcareData CentersGovernment
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Overview#

The Generac MG300 is a 300 kW modular natural gas generator rated at 300 kW / 375 kVA standby (270 kW / 338 kVA prime) at 60 Hz. It uses a Generac turbocharged 14.2L inline-6 spark-ignited engine and is built on the Modular Power System (MPS) platform with a Power Zone Pro Sync controller for factory-integrated paralleling. This is a strong fit for hospitals, campus facilities, and commercial buildings that need 300 kW of gas-fired backup. The MPS architecture enables N+1 redundancy configurations where multiple MG units operate in parallel.

Our Service Experience#

The MG300 pushes the Generac 14.2L inline-6 to 300 kW (227 psi BMEP per the spec sheet), which is the maximum output for this platform. Exhaust temperatures reach 1,415 F at rated output — turbocharger and exhaust valve condition monitoring are critical service priorities. Gas supply infrastructure must be sized for the 3,420 CFH demand at full load. The Power Zone Pro Sync controller manages paralleling when multiple MG units are deployed. We recommend verifying controller firmware is current at each annual service.

Engineering specifications

Physical

Length
136 in
Width
57.1 in
Height
67.9 in
Dry weight
6,200 lb

Documents & downloads

Spec sheets & manuals

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Estimate runtime for the Generac MG300

Adjust load percent and tank size to estimate runtime. Pre-filled with this model's spec where available.

Estimate runtime on this tank

Fuel demand at 75% load

3,150,000 BTU/hr≈ 3150.0 cf/min @ 1,000 BTU/cf

On utility natural gas the runtime is generally unlimited provided the supply line and meter can deliver this BTU/hr at the engine's required inlet pressure (typically 5–14" WC residential, up to 5 psi commercial). Confirm against the OEM's published fuel-pressure spec.

Service intervals

Manufacturer-recommended intervals for the Generac MG300 under standby duty. Field intervals may differ based on load profile, ambient conditions, and fuel quality.

Oil & filter
Every 500 hours or 12 months
Air filter
Every 1000 hours
Spark plugs
Every 2000 hours
Load bank test
Every 12 months

Common failure modes

What we've seen fail on this platform. Use as a service-planning reference, not a diagnostic — actual failure modes depend heavily on duty cycle and maintenance history.

ComponentSymptomTypical hoursSeverity
Spark plugsMisfiring, rough running, reduced power output2,000+minor
Gas regulator / fuel trainUnstable speed, hard starting, fuel pressure faults15,000+moderate
Paralleling controller synchronizationFailed sync, load sharing imbalance, hunting20,000+moderate
BatteryFailed to start, slow cranking8,760+minor

Frequently Asked Questions

What is the difference between the MG300 and the SG300?
The MG300 is a 300 kW gaseous generator built on Generac's Modular Power System (MPS) platform using a turbocharged 14.2L inline-6 engine with factory-integrated paralleling capability. The SG300 uses the same 14.2L engine platform but is configured as a standalone unit. The MG300's MPS architecture enables N+1 redundancy configurations and the ability to service one unit while others continue operating.
What fuel types does the MG300 support?
The MG300 supports both natural gas and liquid propane (LP/LPG). Natural gas is the most common fuel choice as it eliminates fuel storage requirements and provides unlimited runtime with utility gas service.
What voltages are available?
The MG300 supports three-phase configurations: 120/208V, 277/480V, and 346/600V at 60 Hz.

Compatible equipment

Transfer switches

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