With a Drain on Power, State Declares Stage 1 Emergency

California power officials declared a Stage 1 power emergency Friday as hot weather and afternoon air conditioning demand drained available electrical supplies in the state.

The California Independent System Operator, or ISO, which oversees operation of about 75% of the state’s power transmission system, said the emergency would be in effect from 2 p.m. until 6 p.m., the hours when electrical demand typically peaks this time of year.

This is the 24th time since May the ISO had declared a Stage 1 alert, triggered when operating reserves on the system dip below 7% of actual load.

The amount of power being sent over the California grid was forecast by the ISO to peak Friday at 40,378 megawatts, well below the 45,884 megawatts record hit on July 12, 1999.

One megawatt is roughly the amount of electricity needed to power 1,000 homes.

A Stage 2 alert is declared if reserves drop below 5% of load, followed by a Stage 3--the highest level--if the strain on the system threatens to damage transmission equipment and cause widespread blackouts.

California has never gone to a statewide Stage 3 emergency but has come close several times this summer as the state’s appetite for electricity continues to grow at a rate faster than new power plants are being built to satisfy it.