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Cummins/Onan NTA855 — Generator Set Grounding Procedure

Maintenance · Medium voltage generator set (>600 V)

For the Cummins/Onan NTA855, from the Cummins/Onan service manual.

Applies to: Cummins/Onan DFAB, Cummins/Onan DFAC, Cummins/Onan DFBF, Cummins/Onan DFCC, Cummins/Onan DFCE, Cummins/Onan NTA855, Cummins/Onan LTA10 engine, Cummins/Onan NT855 engine, Cummins/Onan NTA855 engine

Before you start

  • No person should attempt these procedures unless fully trained in medium voltage grounding procedures with necessary safety tools and equipment.
  • Hazardous voltage. Can cause severe personal injury or death. Reconnect Grounding Cluster to remove static charge from the winding after each generator test.

Procedure

  1. Open, lock-out and tag-out all sources of power to immediate work area.
  2. Disable starting system: disconnect battery charger AC source, remove negative battery cable, install lockout device on cable end.
  3. Put on high voltage gloves with leather protectors.
  4. Using two pre-tested voltage detection devices, verify de-energized condition; retest devices.
  5. Remove metal cover from generator output box to access generator load terminals.
  6. Securely install Grounding Cluster ground clamp to a verified grounded conductor.
  7. Leave grounds connected one minute to insure static charge dissipation; remove ground cluster to perform tests.
  8. When work is complete, remove Grounding Cluster in reverse order of installation.
  9. 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 Amazon

Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.

Specs & values

  • Leave grounds connected for one minute

Full service-parts list: Cummins/Onan DFBF →, Cummins/Onan DFCC →, Cummins/Onan DFCE →

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.

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