The first transforming station was an outhouse at Grosvenor Gallery receiving alternating current (based on Nikola Tesla’s design) from the world’s first power station in Deptford. It was destroyed by fire in 1890. Substations enabled mass production and capital growth, routing and distributing power to far-reaching places. The grounded infrastructure assemblage varies in size, housing the switching arrangements of connected hardware and software which control and monitor power consumption. Protected from attack they are entombed within fenced enclosures or purpose-built buildings, or are underground, from where their electric fields can be faintly detected. Substations are interconnectors within the largest machine, the oldest networked system: ‘the power grid’.