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3.3 Power Supply Overview

This document provides an overview of the estate power supply, including grid connection, distribution, protection, and backup power arrangements. Sub-pages provide detailed specifications for the grid connection and backup systems.

System Status

Current Assessment

The estate electrical supply is operational. Routine inspection, testing, and preventative maintenance are required to ensure ongoing reliability and safety.

Supply Architecture

  • Primary Supply: Utility grid connection feeding the main switchboard (MSB)
  • Distribution: Sub‑mains supply to estate facilities and common infrastructure
  • Backup Supply: Generator-based backup (with manual or automatic transfer, where installed)

Protection and Metering

  • Metering: Utility revenue meters at point of supply; sub‑metering where applicable
  • Protection: Circuit breakers and RCDs per AS/NZS 3000; surge protection at MSB and sensitive loads
  • Earthing: MEN system per AS/NZS 3000; equipotential bonding at metallic services

Load Management

  • Prioritise critical services: water supply (bore pumps, treatment), wastewater pumping, critical lighting, comms
  • Implement staged start and load shedding when on backup to avoid overloads

Operations and Maintenance

  • Routine Checks: Visual inspection of MSB, enclosure integrity, labelling, indications, and ventilation
  • Testing: RCD push-button monthly; trip-time testing annually; verify SPDs; thermographic scans annually
  • Documentation: Keep single line diagrams, test records, and maintenance logs current and accessible

Safety and Compliance

  • Comply with AS/NZS 3000 (Wiring Rules), AS/NZS 3010 (Generators), and relevant utility service rules
  • Lock‑out/Tag‑out for all work; maintain clearances and ingress protection ratings
  • Signage and labelling on all switchboards, transfer switches, and isolation points

Risks and Mitigations

  • Overload or Nuisance Trips: Review protective coordination; stage large motor starts; verify cable sizing
  • Surge/Lightning: Maintain SPDs; verify earthing and bonding; inspect after storm events
  • Backup Failure: Monthly test runs under load; maintain fuel; service per OEM schedule

Sub-Pages

Version Control

Version Date Description
1.0 2025-10-06 Initial Release

Next Review Date: 2026-04-06