The Generac SG250 is a 250-kilowatt turbocharged natural gas and propane standby generator — Generac's mid-range industrial gaseous unit targeting large commercial buildings, medium hospital facilities, multi-building campuses, and industrial operations. All configurations are three-phase, reflecting the distribution requirements of this capacity class. The SG250 supports three voltage options including 346/600V for Canadian and specialized industrial applications.
At 250 kW, gaseous standby becomes a credible alternative to diesel for facilities where natural gas infrastructure already exists and fuel storage logistics are a concern. The SG250's UL 2200 listing and NFPA 110 Level 1/2 compliance support permit approval for life-safety and emergency standby applications.
The 250 kW gaseous segment is where Generac's industrial dealer network matters most — facilities at this scale typically have service contracts and expect rapid emergency response. The turbocharged Generac industrial engine in the SG250 requires the same scheduled ignition and turbo maintenance as the SG200, at intervals appropriate for the unit's runtime hours. We recommend confirming local Generac industrial dealer coverage before specifying the SG250 for life-safety applications.
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Tell us about the application — kW, voltage, application, install timeline — and we'll respond within one business day with budgetary pricing, lead time, and any sizing notes.
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
2,625,000 BTU/hr≈ 2625.0 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 SG250 under standby duty. Field intervals may differ based on load profile, ambient conditions, and fuel quality.
Oil & filter
Every 250 hours or 12 months
Coolant change
Every 4000 hours
Air filter
Every 1000 hours
Spark plugs
Every 1500 hours
Major overhaul
≈ 15,000 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.
Component
Symptom
Typical hours
Severity
Turbocharger
Loss of power, excessive smoke under load
12,000+
moderate
Spark plugs / ignition
Misfire at load, rough running
1,500+
minor
Charge air cooler
Reduced power output, elevated intake temps
10,000+
moderate
Battery
Failed to start during outage
8,760+
minor
Frequently Asked Questions
Is the Generac SG250 available in single-phase?
No. At 250 kW, the SG250 is a three-phase-only unit. Single-phase loads at this scale are uncommon in commercial construction; three-phase distribution is standard for large commercial, industrial, and healthcare facilities.
Can the SG250 be used in a paralleling array?
Yes. With Generac's paralleling controller option, multiple SG250 units can be synchronized to achieve higher aggregate capacity or provide N+1 redundancy. This is a common configuration for data centers and mission-critical facilities that need scalable gaseous standby without committing to a single large diesel unit.
What is the difference between the SG250 and SG300?
Both share the turbocharged Generac industrial platform and three-phase-only configuration. The SG300 provides 50 kW more standby capacity, making it appropriate when load calculations show sustained demand approaching 250 kW or when future load growth is anticipated.
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