Cummins/Onan P1700i — Measuring insulation resistance
Testing & diagnosis · Generator
For the Cummins/Onan P1700i, from the Cummins/Onan service manual.
Applies to: Cummins/Onan P1700i, Cummins/Onan EH09-2D engine
Before you start
- If insulation resistance is less than 1 MΩ, disassemble the generator and measure stator, rotor and control panel individually.
- Insulation failure may cause electrical leak which may result in electrocution.
Procedure
- Short-circuit the terminals of an AC receptacle using a wire to discharge remaining electricity.
- Connect the megger tester across either one output terminal of the AC receptacle and the ground terminal.
- Measure with the AC breaker on.
- An insulation resistance of 1 MΩ or more is normal (factory value is 10 MΩ or more).
Tools required
- Megger tester (500 V range) Amazon
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Specs & values
- 1 MΩ or more normal; 10 MΩ or more at factory shipment
Source: Cummins/Onan 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.