They don't "reset" it. A cable TV network will continue to operate as long as it's physically intact and has operating power available. At any given customer location, it's entirely possible for the power to be off, but cable TV to be operating normally.
Virtually all cable TV facilities are now protected by backup power:
- Headends are protected by on-site standby generators. Some headends also have batteries to cover transitions between utility power and generator power.
- Nodes are protected by batteries capable of maintaining service for several hours. They are equipped with power input connectors and transfer switches to accept power from vehicle-mounted generators (similar to telco DLC cabinets).
- Pole-mounted power supplies are also protected by batteries. During extended outages, they can be connected to vehicle-mounted generators (standard off-the-Home-Depot-shelf generators work fine).
A more likely reason for simultaneous power-and-cable TV outages is plant damage. If a poleline is damaged (falling tree, drunk driver, house fire) it's likely to affect everything on the on the line: power, cable TV, and landline telephone. In such situations, the power company always gets its repair work done first; cable and telco crews can't get near the line until power has finished its work and declares the area safe.
All of which means that cable TV indeed "stays out" until after power is restored. But it doesn't necessarily mean that the same customers are affected. Depending on the topology of the cable network vis-a-vis the power network, it's possible for the cable signal and electric power to be running in opposite directions along the same poleline. In such situations, a damaged poleline would affect different sets of customers. A house fire at a critical intersection could knock out power on the north side of town, cable TV service on the west side, and landline telco service on the south side.
Neal McLain