Electricity is produced at the power station. The National Grid network From the step-up transformer the electricity is distributed across the country through a network of overhead and underground cables. They carry electricity at a voltage of at least 132,000V The power station Electricity is produced at the power station. Power stations produce electricity at a voltage of 25,000V Homes The underground mains cables runs into houses carrying electricity at a voltage of 230V Underground mains cables These run away from the step down transformer. They carry the electricity at a voltage of 230V Step down transformers These are local substations, they are connected to the National Grid Network and step the voltage down to 230V Step up transformer Outside the power station is a step up transformer. This increases the voltage to at least 132,000V