The impact of electric vehicles (EVs) and heat pumps (HPs) on the voltages seen on a low voltage (LV) feeder is investigated in this paper. The Monte Carlo (MC) method was adopted to understand the impact of diversity of demand on LV feeders and especially the effect of uncontrolled human behaviour. The statistical models of EV demand and HP demand were established and a simulation study was carried out in both balanced and unbalanced scenarios. Moreover, the effectiveness of the TOU tariff on mitigating the violations of the voltage limits caused by EVs and HPs was investigated and the result shows that the TOU tariff helps to shorten the violation time period but may induce a new violation period.