Henderson Substation


  • Location: Auckland
  • Year: 2016

Technical Overview

Construction of a new ODID building including cable stand foundations, direct buried cable trenches, precast cable troughs, drainage and demolition of existing 33kV bank foundations.

The existing 33kV switchyard was replaced with indoor gas-insulated switchgear housed in a new ODID building.

The location of the building was in close proximity to overhead cables and the existing 33kV bank so protection measures were introduced to protect site personnel and the client’s assets. Movement corridors were restricted to designated areas defined by temporary fencing and barriers.

Connell’s scope included:

– Construction of a new 33kV switchroom building
– Construct cable stand foundations
– Excavate/backfill feeder cable trenches
– Manufacture and install Connell’s precast concrete troughs
– Install stormwater drainage scheme
– Demolish existing 33kV bank
– Re-metal existing switchyard yard

The two storey building is constructed of concrete blocks with insulated roof panels. Midfloor was cast in situ to accommodate the new switchgear panels. Cable entry was through penetrations in the basement. All structural steel was coated with intumescent paint for fire protection.

Connells manufactured and installed precast concrete troughs for cable access. Cable stand foundations were cast in situ and connected to the existing transformer bank.

Extensive cable trenches were formed through the existing switchyard where many high voltage cables and earth straps had to be negotiated – none were damaged. TPCR40 was laid through the construction zone to complete the yard works.

A stormwater drainage scheme was installed to accommodate the new building roof catchment including the basement pumps. The project was completed on time and budget with no serious harm incidents reported.

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