ENE/General/TBT-ENE-014

Substation Upgrade for EV Loading

Energy & Renewables › General › Substation Upgrade for EV Loading

Presenter		Project
Location		Date

EV charging hubs require significant electrical capacity, often necessitating new or upgraded substations.
Substation construction involves excavation, civil works, HV cable installation, and transformer delivery.
High voltage equipment operates at 11kV or 33kV — contact or proximity causes instant fatal electrocution.
Only HV authorised persons may enter live switchgear rooms or operate HV switching equipment.
Transformer oil (mineral or ester-based) is a potential environmental pollutant requiring bunded containment.
HV cable jointing is a specialist activity requiring specific training and controlled clean conditions.
Coordination with the distribution network operator (DNO) is required for connection and commissioning.
The substation must be designed to accommodate future EV demand growth, not just current requirements.
Arc flash hazards at HV switchgear require arc-rated PPE for all persons in the arc flash boundary.
Commissioning involves first-time energisation of HV equipment with a detailed switching schedule.

Fatal electrocution	HV equipment at 11kV or above causes instant death on contact or flashover — strict access controls are essential.
Arc flash	HV switchgear faults produce arc flash with extreme heat and pressure, causing fatal burns and blast injuries.
Environmental risk	Transformer oil spills contaminate soil and groundwater, requiring bunded containment and spill response.

Don't

Ensure only HV authorised persons access live switchgear rooms and operate HV equipment
Wear arc-rated PPE including face shield and gloves within the arc flash boundary
Follow the approved switching schedule for all HV energisation and commissioning activities
Install bunded containment for transformer oil to prevent environmental contamination
Coordinate all HV connections and commissioning with the distribution network operator
Use HV cable jointers with specific certification for the cable type and voltage class
Complete a detailed risk assessment for every phase of the substation construction
Establish exclusion zones around HV equipment during testing and commissioning
Verify all safety interlocks, earth switches, and protection systems before first energisation
Brief the entire team on the HV hazards, boundaries, and emergency procedures daily

DON'T allow unauthorised persons near HV switchgear or live electrical equipment
DON'T approach HV equipment within the arc flash boundary without arc-rated PPE
DON'T energise HV equipment without a fully approved switching schedule in place
DON'T carry out HV cable jointing without the specific certification for that voltage class
DON'T spill transformer oil — contain it immediately using the site spill response kit
DON'T bypass HV safety interlocks or earth switches during any phase of the works
DON'T commission HV equipment without coordination and approval from the DNO
DON'T work on civil excavations beneath HV cables without confirmed isolation or protection
DON'T undersize the substation — design for future EV demand growth from the outset
DON'T treat LV and HV commissioning as the same — HV requires specialist procedures

See also: High Voltage (HV) Safety | EV Charging Electrical Installation

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