In electricity distribution networks, spot network substations are used in interconnected distribution networks. They have the secondary network (also called a grid network) with all supply transformers bussed together on the secondary side at one location. Spot networks are considered the most reliable and most flexible arrangement of connecting power to all types of loads. Switching can be done without interrupting the power to the loads.
Urban [Spot] network substations can be used to make the interconnected distribution networks to serve a single campus or facility. Examples of such single campuses and facilities include airports, hospitals, major data processing centers (especially those using uninterruptible power supply), and sports arenas that regularly broadcast nationally televised events.
EPRI lists urban network supply systems has having Momentary and Long-duration Interruptions on 50 year intervals .
In large cities, many electric utility companies use grid feeders to make interconnected distribution networks to serve the downtown core. The interconnected network has multiple connections to the points of supply.
Reverse current relays are used to detect any open circuits that are letting the electrical current flow back towards its source.