EV Charger Cabling & Power Supply in Singapore
A technical reference for facility managers, M&E consultants and contractors planning EV charger installations in Singapore — covering cable sizing, SS 638 requirements, load management for condominiums and industrial sites, and when a 22kV HV feeder is needed to support fast-charging hubs.
1. Charger ratings and supply types
2. SS 638 requirements for EV charging
EV charging installations in Singapore are governed by SS 638 (Singapore Standard for Electrical Installations), including its EV-specific sections. The headline requirements: dedicated final circuits (one circuit per charger), Type B RCD protection (to detect smooth DC residual currents that Type A misses), correct earthing arrangement (TT or TN-S per the building intake), and proper voltage-drop calculation for the cable run from the distribution board to the charger.
3. Load management for condominiums and carparks
Most Singapore condos cannot upsize their SP Group intake just to add EV chargers — the economics rarely work. Instead, modern installations use dynamic load management: a controller monitors the building's live demand and throttles each charger so the total never exceeds the available headroom. This lets a 200–300A site safely run 10–20 AC chargers off the existing intake. Cable infrastructure is still sized for the full theoretical load to keep the system future-proof.
4. When you need HV (22kV) infrastructure
Once a charging hub's peak demand exceeds the LV intake capacity of a single building — typically around 200–500kVA — the cheaper option is a dedicated HV feeder from SP Group. The works package then becomes:
- 22kV underground cable installation from the nearest SP substation
- HT cable jointing & termination at the substation and customer side
- 11/22kV step-down transformer (typically 500kVA–2MVA for fast-charging hubs)
- LV distribution to the chargers, with metering and load management
- VLF / Hi-Pot testing of the HV cable before energisation
5. Cable types commonly used
- LV final circuit to charger: XLPE/SWA/PVC copper, single or multi-core, sized 6–35mm² for AC chargers
- LV submain to charger bank: XLPE/SWA copper, typically 95–300mm²
- HV feeder: 22kV single-core or three-core XLPE, copper or aluminium, sized per SP Group spec
6. Common mistakes to avoid
- Skipping Type B RCD — Type A does not detect DC residual current and is non-compliant for most modern EV chargers.
- Sharing a circuit between two chargers — every charger needs its own dedicated final circuit under SS 638.
- Undersizing cables for voltage drop on long carpark runs — leads to charger faults and reduced charging power.
- Forgetting future expansion — running a single 25mm² to a charging bay today often forces a full re-cable in two years.
Planning an EV charging installation in Singapore?
We provide the underground cable installation, HT and LT cable jointing, termination and VLF/Hi-Pot testing for EV charging projects across Singapore — from a single fast-charging bay to a full HV-fed hub.
Frequently asked questions
What cable size do I need for an EV charger in Singapore?
Cable sizing depends on the charger rating, run length and installation method. As a rough guide: a 7.4kW (32A) AC charger typically runs on 6mm² copper for short runs; a 22kW (32A three-phase) on 6–10mm²; and a 50kW+ DC fast charger on dedicated LV feeders sized per SS 638 voltage-drop calculations. Always confirm with a Licensed Electrical Worker.
Do EV charger installations need to follow SS 638?
Yes. EV charging installations in Singapore fall under SS 638 (Singapore Standard for Electrical Installations), including the EV-specific sections covering circuit protection, RCD requirements (Type B for DC fault current), earthing, and dedicated final circuits.
When does an EV charging hub need HV cable infrastructure?
Fast-charging hubs with multiple 50kW+ DC chargers typically exceed the LV intake capacity of a single building. From around 200–500kVA peak demand, the most economical option is a dedicated 22kV HV feeder from SP Group, an 11/22kV step-down transformer and LV distribution to the chargers — which is where HT cable jointing comes in.
Who can install EV charger cabling in Singapore?
LV final-circuit work to the charger must be carried out by a Licensed Electrical Worker (LEW). HV feeder works (22kV/11kV) require an SP Group permitted cable jointer in addition to the LEW design and supervision.
Do you do EV charger cabling for condominiums and industrial sites?
Yes. We provide the cable jointing, termination, testing and underground cable installation for EV charging projects across Singapore — from single-tenant industrial fast-charging bays to full condominium load-managed installations.