Most customers use electricity at 230 volts. This is known as low voltage electricity which can only travel a short distance therefore we have lots of local substations where the power comes in at high voltage (usually 11,000 volts) and we reduce it to the low voltage (230 volts) you use in your home.

We can send power at high voltage over tens of kilometres from our main substations.

Medium-sized towns usually have one main substation supplying the town and the rural area beyond whereas larger towns may have two or three main substations and possibly a Grid substation too.

At the highest voltages there are two or more of most pieces of equipment so the occasional breakdown does not affect customers' power. At the lower voltages however it costs too much to have two of everything, and breakdowns can affect customers. To combat this our network is designed to interconnect with alternative circuits where possible. This means that when a fault happens we can use the alternative circuit to get power back on quickly. We can operate most of our high voltage equipment from our control centres. When there's a high voltage fault we know about it straight away however if the fault is on the local low voltage system we won’t know about it until you tell us. That’s why you we ask that you call us if you do have a power cut.

Click here for details on how to contact us.