Investigating Potential New Load Patterns on Distribution Transformers from Residential Electrification

As nations set ambitious targets to phase out internal combustion engine (ICE) vehicles and electrify transport and household systems, it is anticipated that there will be a surge in demand for electric vehicles (EVs), heat pumps (HPs), and electric water heaters (EWHs). Utility providers must assess what this shift means for the existing grid. Although generation may be sufficient, attention must turn to local distribution, particularly individual street- level transformers. As EV chargers are installed and households replace gas systems with HPs and EWHs, the grid faces rising pressure. Many consumers prefer to charge vehicles at home in the evening, placing extra demand on local infrastructure. When several residents charge EVs while using water heating and cooling systems, transformer capacity may be exceeded. This study uses data from an Ontario utility to examine new loading scenarios as EVs, HPs, and EWHs are adopted in Canadian neighbourhoods. One transformer showed a maximum hourly load increase of 706.59% at 25% uptake and 1292.22% at 50%. Sustained high loads accelerate insulation ageing and raise the risk of early failure, with overloads possible when 11 EVs charge simultaneously at high speed.