Generac GT-990 — Stator Insulation Resistance Test
Testing & diagnosis
For the Generac GT-990, from the Generac service manual.
Browse Generac generators & specs →
Before you start
- Disconnect and isolate all leads before testing.
Procedure
- Disconnect stator output leads 11 and 44 from main line circuit breaker.
- Remove stator output leads 22 and 33 from neutral connection and separate.
- Disconnect C2 Connector from side of control panel.
- Connect terminal ends of Wires 11, 22, 33, and 44 together.
- Connect red Hi-Pot test probe to joined leads; black lead to clean frame ground.
- Set tester to 1500 volts and apply for one second only.
- Observe breakdown lamp.
- If lamp comes on, clean and dry stator, then repeat test.
- If second test fails, replace stator assembly.
Tools required
- Hi-Pot tester Amazon
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Specs & values
- Do not apply voltage longer than 1 second
- Minimum insulation resistance: rated volts / 1000 + 1 megohm
Source: Generac service manual. Steps and values are as documented; always cross-check against the official manual and any later revisions for your exact serial number before servicing.