3794

Common Causes

• Lighting cable shorted between conductors
• Lighting cable or fixture shorted to ground (chafed insulation touching the machine frame)
• Failed work light fixture or lamp socket drawing excess current
• Moisture or coolant inside a light fitting causing a leakage path

Troubleshooting Steps

1. 1Lock out the main power and verify the circuit is dead before opening the EC power unit or any light fixture.
2. 2Inspect the work light fixtures and their cable runs for crushed insulation, coolant inside the housing, or bare wire touching the frame.
3. 3With power locked out, disconnect the lighting load at the power unit, then re-energize and reset the breaker; if it holds, the fault is in the lighting circuit, not the power unit.
4. 4Reconnect lights one at a time (or test each branch with a meter) to isolate which fixture or cable section trips the breaker.
5. 5Repair or replace the shorted cable or fixture, confirm the breaker holds under normal lighting load, and only then return the machine to service.
6. 6If the breaker trips even with all lighting disconnected, the fault is inside the EC power unit; record the alarm number and contact Okuma service.