Relating to the reliability of the electricity supply chain.

HB 4851 requires electricity providers in Texas' ERCOT power region to conduct regular practice drills focused on maintaining grid stability during emergencies. Specifically, it mandates annual summer and winter load-shedding exercises for all electric generation, transmission, and distribution providers, plus additional attack-preparation drills every two years if a critical facility (like a key substation) faces physical threat. The bill ensures these drills clearly define roles for providers, law enforcement, the grid operator, and the state utility commission. It also protects providers from having to disclose exact locations of critical infrastructure during these exercises. The law applies directly to all electricity service providers operating within ERCOT's grid.