Energy shortages are declared by Cal-ISO (California Independent System
Operator), the nonprofit agency that manages the state electric
transmission system. Cal-ISO balances the supply of electricity from
generators inside and outside the State, with the demand for electricity
from users. Shortages occur when there is not enough power available to
support the needs of residents and businesses throughout California.
When demand exceeds supply, or demand is more than the transmission
system can move from the generators to your utility, Cal-ISO takes steps
to keep the system in equilibrium and avoid grid failures. These steps
can include day-ahead Warnings, Alerts, or Stages of Emergency.
- Stage One Emergency: Takes effect when electric
generation reserves fall below seven percent statewide. The media is
alerted and electric consumers are asked to reduce unnecessary
- Stage Two Emergency: Is declared when reserves drop
below five percent. At this level, large commercial customers
throughout the State who have contracts to curtail power during high
demand are asked to do so. Silicon Valley Power also asks Santa Clara
businesses and residents to voluntarily reduce power usage during a
Stage Two Emergency.
- Stage Three Emergency: Is initiated when generation
reserves fall below one and one-half percent and can result in rolling
blackouts among large blocks of electric utility customers throughout
California, including Santa Clara.
A Stage Three Emergency alert is serious. If more power
generation is not found and/or customers do not reduce energy use
enough, the entire electric grid could fail. This would affect everyone
regardless of their source of power. Because of this, all utilities
throughout the State are required to reduce their energy load during a
Stage Three Emergency.
In Case of a Power Alert…