Substation Civil Construction SWMS

Substation civil construction involves the formation of reinforced concrete plinths, transformer bunds, cable trenches, earth grids and perimeter security fencing within or adjacent to energised high-voltage switchyards. This work is High Risk Construction Work under WHS Regulation 2011 r291 because it is performed in proximity to energised electrical installations exceeding the no-go zones in AS 5804, frequently involves excavation greater than 1.5 metres for cable routes and earth mats, and includes structural concrete work supporting plant in excess of 25 tonnes. A documented Safe Work Method Statement is mandatory before any work commences on site and must be developed in consultation with workers under WHS Act s47. The SWMS must address electrical induction from adjacent live conductors, mobile plant clearance from live apparatus, and the coordination interface with the network operator's access permit system. Failure to prepare, communicate and monitor a compliant SWMS exposes the PCBU to enforcement under WHS Regulation r299–r300 and personal liability for officers under WHS Act s27.

Hazards identified

7 hazards covered, sorted by priority.

Control measures

Hierarchy-of-controls order: elimination → substitution → isolation → engineering → administrative → PPE.

1. 1Elimination — Sequence civil works to occur during a network access permit with adjacent feeders isolated, earthed and tagged before any plant enters the switchyard footprint.
2. 2Elimination — Prefabricate fence panels, formwork cages and bund liners off-site to remove cutting, welding and grinding activities from the live substation environment entirely.
3. 3Substitution — Replace diesel concrete boom pumps with line pumps and ground-level placement to remove elevated boom encroachment risk into HV no-go zones under AS 5804.1.
4. 4Substitution — Use self-compacting concrete and screw-pile bund anchors to substitute for vibrator and percussion-driven plant near sensitive protection relays.
5. 5Engineering — Install temporary insulated tiger tails, goal posts and physical barricades at AS 5804.1 clearance distances, verified by the network operator's authorised access officer before plant mobilisation.
6. 6Engineering — Bond all formwork, rebar mats and crane outriggers to the station earth grid using 70 mm² copper conductors to dissipate induced voltages to ground.
7. 7Engineering — Shore all excavations over 1.5 m with hydraulic struts or trench boxes designed by a competent person under AS 5100 and the Excavation Work Code of Practice.
8. 8Administrative — Conduct daily pre-start briefings against this SWMS, network operator switching program and JSEA, with sign-on register retained for the project plus two years.
9. 9Administrative — Restrict access using a switchyard entry permit system; only HV-inducted workers holding current EWP, dogging and confined space tickets enter the live yard.
10. 10PPE — Issue Cat 2 arc-rated coveralls (minimum 8 cal/cm²), Class 00 insulated gloves, P2 respirators for silica tasks and dielectric boots compliant with AS/NZS 2210.3.

Applicable Codes of Practice

High-Risk Construction Work triggered

Worked example

On a 132/33 kV zone substation augmentation in a regional industrial precinct, the civil crew is pouring a new transformer plinth and bund three metres from an energised 132 kV busbar that cannot be isolated due to network load. At the 6:30 am pre-start, the site supervisor opens this SWMS on a ruggedised tablet and works through the hazard register with the four-person crew, the concrete pump operator and the network operator's authorised access officer. The induction hazard row prompts the team to verify that the rebar cage and pump boom are bonded to the station earth grid with a 70 mm² copper conductor, which the leading hand tests with a clamp meter before the pour. The no-go zone control triggers the access officer to confirm the tiger tails and goal posts are positioned at the AS 5804.1 vicinity distance for 132 kV, and the pump operator demonstrates the boom-height limiter setting. Each worker signs the SWMS sign-on register, noting their HV induction expiry. Mid-pour, wind gusts increase and the spotter calls a stop because the boom is drifting toward the vicinity zone; the supervisor reopens the SWMS, applies the documented adverse weather trigger, and the crew switches to a ground-level line pump for the remaining two cubic metres. The amendment, the stop event and the resumed sign-on are recorded against the SWMS revision log for retention.

Related legislation

• WHS Act 2011 (model)
• WHS Regulation 2025
• AS/NZS 3000 — Electrical installations; AS/NZS 3012 — Electrical installations construction sites

Frequently asked questions