With reference to emergency electrical power in cargo ships, describe the source, list essential services, and explain testing?

flowchart TD
    A[Emergency generator above bulkhead deck] --> B[Independent fuel & starting means]
    B --> C[Supplies emergency switchboard]
    C --> D[Emergency lighting]
    C --> E[Navigation lights]
    C --> F[General alarm]
    C --> G[Daylight signalling lamp]
    C --> H[18-hour endurance for cargo ships]

• Source: diesel generator above the uppermost continuous deck, independent fuel and starting means
• Services: emergency lighting, navigation lights (if electric), general alarm (if electric), daylight signalling lamp (if applicable)
• Duration: 18 hours for cargo ships
• Testing: routine on-load tests and simulated blackout tests
• Trap: must be independent of main power and protected from fire/flooding in main machinery spaces