Electric reliability is often presented as a single score. In practice, regulators track several measures, and each describes a different part of the system.

System-wide supply asks whether enough electricity is available when demand peaks. Distribution reliability tracks interruptions closer to homes and businesses. Public-safety shutoffs, storm damage and equipment failures can therefore move the figures in different directions.

The distinction matters when comparing utility performance or evaluating a proposed investment. A statewide reserve margin cannot explain a neighborhood outage, while a local outage count does not by itself indicate a shortage of generation.

Sources & methodology

This report was written from the primary materials below. Links open at the original publisher.

California Public Utilities Commission

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