Kohler 20RZ, 25RZGB, 30RZGB, 50RZGB, 150RZGB, 30RZG, 125RZG, 35RES, 125RES Industrial Generator Sets Wiring Diagrams (tp6274)

These Kohler industrial generator sets usually sit in plant rooms, hospitals, data centers, or outdoor enclosures, picking up the load when the main power drops. This wiring-diagram manual is what I’d keep open when I’m tracing control circuits or verifying a harness after a repair. If the set won’t crank from the automatic transfer switch, for example, I use this to follow the start signal from the controller, through each connector and relay, until I find where it dies.

Applications & Use Cases

• Trace wire routing from the controller to relays, sensors, and actuators so you can isolate a bad connection instead of guessing.
• Verify harness repairs after replacing damaged loom or connectors, confirming each pin lands where it should.
• Check retrofit work, like adding remote start/stop or monitoring, making sure you tie into the correct terminals without backfeeding anything.
• Continuity-test circuits with a meter, using the diagrams to know which two points should talk to each other.
• Confirm correct grounding and shielding on sensitive circuits to prevent nuisance shutdowns and false alarms.

FAQ

Q: Can I use this on a tablet at the jobsite?

A: Yes, it works well digitally; you can zoom in on connector callouts and wire IDs while you’re at the generator.

Q: Is it worth printing parts of it?

A: I’d print the diagrams for the specific model I’m working on and keep them in a plastic sleeve near the set for quick reference.

Safety Note

Always lock out/tag out all power sources and verify zero voltage before opening panels or handling any wiring.