It’s those hot nights that spur outages

Southern California has been struggling through a summer heat wave, with thousands of residents suffering power outages again on Monday. The Times talked with officials from Los Angeles Department of Water and Power and Southern California Edison about why there are outages and what you can do to keep the lights on.

Why is the power failing?

The simplest answer is persistent, high nighttime temperatures. Southern California systems are designed to handle high daytime temperatures, then cool down at night when customers switch off their air conditioners. But in recent days, the temperature has been as high as 95 degrees at night in some areas, prompting residents to keep their air conditioners running all night. This causes the oil in small transformers that each serve up to 25 homes to overheat and fail. On Tuesday, about 29,000 Los Angeles residents were without power, according to DWP officials.

Are aging transformers and other equipment to blame for the outages? If so, what is being done to upgrade older infrastructure?

The number of outages during the current heat wave are about half of what they were during a similar weeklong spell last summer because of stepped-up efforts to fix or replace faulty or aging transformers, power poles and circuits. Most of Southern California’s equipment was built just after World War II, and its normal life expectancy is 40 to 60 years. Homes are also sucking in more power because of new electronics like 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. Both Los Angeles Department of Water and Power and Southern California Edison are in the middle of large retrofitting and replacement programs. The DWP recently replaced or repaired 3,000 transformers at a cost of $13.5 million and is seeking to spend $1 billion more over the next five years for new equipment. Edison replaced 9,000 power poles in the region to prepare for this summer and has pledged to spend a projected $14 billion over the next few years on upgrades and system expansion.

What is a megawatt?

A single megawatt is equal to 1 million watts and can supply up to 250 homes. Last Friday was the highest energy demand period of the summer, with Southern California Edison reporting energy use at 23,303 megawatts, breaking last year’s record of 22,889. On that same day, DWP reported energy use at 6,107 megawatts, the second-largest daily use ever. The state energy grid hit 48,617 megawatts.

What should the average consumer do to keep the lights on?

Keep the air conditioner thermostat set at 78 degrees, or low to medium. Edison officials recommended turning off air conditioners during the daytime, if possible, and then running them at 78 degrees at night. But DWP equipment managers say it is more efficient to keep your air conditioner on at 78 degrees throughout the day, rather than expending large amounts of energy to try to cool down a house at night. Other tips include keeping shades drawn and vents closed, if possible. Do not run washing machines and dryers in the daytime, particularly in the San Fernando Valley.

There have been several heat-related deaths in the past few days, including an elderly couple whose air-conditioner was not on. Should people turn off the air conditioner when they are at home during a heat wave to try to conserve power?

Individual health and safety comes first. Keep your air conditioner on, particularly if you are elderly or have health problems. If you are having trouble paying your bills, discount programs are available for elderly and low-income customers. If you have no air conditioner, you are advised to stay with family or go to a commercial area or building that is air conditioned.

How does Edison’s voluntary shut-down program work? Can you get your air conditioner turned back on under that program in an emergency?

Southern California Edison has 276,000 residential and small commercial customers enrolled in a “voluntary interruption” summer program. Customers can save up to $50 a month in exchange for agreeing to have a device installed on their air conditioners that automatically shuts them down for up to six hours when regional power reserves dip to dangerously low levels. A signal is sent out from a remote location to shut down a group of homes or businesses. It is not possible to override the shutdown signal for individual customers. People whose doctors say they need air conditioning for health reasons are not allowed to participate in the program.

janet.wilson@latimes.com