The Kohler KG125 is a 125-kilowatt commercial standby generator — the top of the 6.2L KG6208 V8 platform, before the lineup transitions to the 10.3L KG10V08T V8 used in the KG150 and KG200. It serves larger commercial facilities, campus-scale buildings, and light industrial operations where 80-100 kW of sustained load demands a genset with margin.
Common deployments: full-service hotels with significant HVAC load, large multi-family residential complexes, school campuses, light industrial facilities, and commercial cold-storage operations where gaseous fuel avoids the diesel storage complications.
Three-phase only at this size — single-phase applications should look at the KG100 or below
The KG125 is the right unit when the KG100 is too close to the line. If your load study shows 75-100 kW peak with HVAC cycling or frequent motor starts, the KG125 provides the headroom that prevents nuisance under-frequency trips during transient loading.
The KG125 shares the KG6208THD turbocharged-aftercooled 6.2L V8 with the KG100, so service procedures are essentially identical. The 500-hour / 12-month oil interval applies. We see these units primarily in hospitality (larger hotels) and multi-family (150+ unit complexes) where the building's common-area load justifies the step up from KG100.
Engineering specifications
Physical
Length
138.8 in
Width
45.4 in
Height
65.5 in
Wet weight
3,562 lb
Acoustic
Sound @ 7m, full load
71 dBA
Enclosure
Sound-attenuated
Fuel system & runtime
BTU/hr @ full load
1,678,000
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Configure your Kohler KG125
Lock the enclosure, fuel system, transfer switch, and add-ons — we'll confirm pricing, availability, and lead time within one business day. Prefer a free-form quote? That option is still here.
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
1,312,500 BTU/hr≈ 1312.5 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 Kohler KG125 under standby duty. Field intervals may differ based on load profile, ambient conditions, and fuel quality.
Oil & filter
Every 500 hours or 12 months
Coolant change
Every 4000 hours
Air filter
Every 1000 hours
Spark plugs
Every 2000 hours
Major overhaul
≈ 20,000 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 bearings / seals
Oil in intake, blue smoke, reduced power
12,000+
moderate
Spark plugs / ignition coils
Misfire under load, cylinder dropout
2,000+
minor
Intercooler system
Boost leak, reduced power, hissing
8,000+
minor
Exhaust manifold / turbo gaskets
Exhaust leak, soot staining, ticking
8,000+
moderate
Parts cross-reference
starting Battery
Group 31 (recommended)
Frequently Asked Questions
What is the standby power rating of the Kohler KG125?
The KG125 is rated 125 kW standby (113 kW prime) at 60 Hz. It uses Kohler's KG6208THD 6.2L turbocharged-aftercooled V8 — the top of the KG6208 platform before the line steps up to the KG10V08T 10.3L V8 used in the KG150 and KG200.
What's the difference between the KG100 and KG125?
Both share Kohler's 6.2L KG6208THD V8 (turbocharged and aftercooled). The KG125 is rated 25% higher (125 kW standby vs 100 kW) through alternator winding and tuning differences. Choose the KG125 when peak demand is 80-100 kW or motor-starting transients are a factor.
What ATS sizing for the KG125?
At 480V three-phase: 200-250A ATS. At 208V three-phase: 400-600A ATS. ASCO 7000 Series or Kohler KCS are common at this capacity.
