Cummins/Onan — Generator Set Grounding Procedure (Medium Voltage)
Maintenance
From a Cummins/Onan service manual — check it applies to your exact model before use.
Applies to: Cummins/Onan DFHA, Cummins/Onan DFHB, Cummins/Onan DFHC, Cummins/Onan DFHD, Cummins/Onan QST30 engine
Before you start
- Hazardous voltage. A definite static charge remains on the windings after DC test voltage is applied; reconnect Grounding Cluster after each generator test.
- Only persons fully trained in medium voltage grounding procedures with the necessary safety tools and equipment may perform these procedures.
Procedure
- Open, lock-out and tag-out all sources of power to the immediate work area.
- Disable the starting system: disconnect battery charger AC source, remove negative battery cable, install lockout device.
- Put on high voltage gloves with leather protectors.
- Using two pre-tested voltage detection devices, verify de-energized condition in the work area; retest devices after verification.
- Remove the metal cover from the generator output box to access generator load terminals.
- Securely install the Grounding Cluster ground clamp to a verified grounded conductor.
- Leave grounds connected for one minute to ensure static charge dissipation, then remove and perform tests; reconnect grounds if more service is needed.
- When work is complete, remove the Grounding Cluster in reverse order of installation.
- After clearance from all personnel, remove all lock-out devices in reverse order of installation.
Tools required
- high voltage gloves with leather protectors Amazon
- two pre-tested voltage detection devices Amazon
- Grounding Cluster ground clamp Amazon
- lockout devices Amazon
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Full service-parts list: Cummins/Onan DFHA →, Cummins/Onan DFHB →, Cummins/Onan DFHC →, Cummins/Onan DFHD →
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.