The heat wave that triggered widespread blackouts around Southern California occurred as the Department of Water and Power underestimated how much power Angelenos would use at one time while overestimating the quality of its equipment, according to interviews and documents.
The record temperatures sent power usage to an all-time high of 6,165 megawatts -- an amount that shocked agency officials.
"They didn't even believe our customers could ever put such a load on our system -- that we could even have energy use from our customers up to that kind of level," said David Nahai, a DWP board member.
Until this week, the highest peak energy use was during a heat wave last summer, at 5,661 megawatts. DWP projections didn't call for energy usage in L.A. to top 6,100 megawatts until four years from now.
But officials said several factors conspired to cause a surge in power use. A week of 100-plus-degree temperatures -- and record heat at night -- prompted many residents to run their air conditioners 24 hours a day.
Moreover, the DWP's projections didn't fully account for the increased energy use of today's larger, highly electronic homes -- including the growing popularity of big-screen plasma TVs, which eat up about as much power as a large refrigerator and about a third the energy of a central air system.
Nationally, power companies are expecting a 50% increase in the power used by televisions as more people convert to more sophisticated sets.
"We were very, very surprised at the experience we were having over the weekend, which was the unbelievable demand," Kim Hughes, a DWP spokeswoman.
DWP Commissioner Nick Patsaouras, an appointee of Mayor Antonio Villaraigosa, blamed the mayoral administration of James K. Hahn for moving money into the general fund that could have been used to upgrade DWP systems.
He said the utility's staff had known for years that its equipment was outdated.
"We know staff knew for a long time," Patsaouras said. "You know when equipment is bad."
The DWP has not yet calculated the total number of customers who lost power. The greatest number of customers without electricity at any given time was 30,000, but the total number of those affected during the course of the heat wave was much higher.
Southern California Edison has said a total of 1.1 million of its customers lost power.
