Big companies are bracing for a possible limit in the power supply as the government is struggling to increase its power reserves to avoid blackouts.

The government issued the “watch” warning across the nation on Tuesday morning as the nation’s power reserve dropped below 4 million kilowatts due to a surge in electricity consumption caused by cold temperatures. It is the fourth-highest level warning after seriousness, vigilance and attention.

The companies’ move came after the Ministry of Knowledge Economy, which is a control tower for energy demand and supply management, said if power reserves keep falling, it will ask companies using more than 3, 000 kilowatts to cut their daily power consumption by up to 10 percent between Jan. 3 and Feb. 22, 2013, to keep its daily power reserves above 4 million kilowatts.

The ministry has no choice but to limit power usage of big power spenders, whether private or public, as the extended cold spell pushes power reserves to an unstable level, officials said.

Companies are developing a variety of ideas to cut power without an impact on their business. Hyundai Heavy Industries, for instance, will reportedly control operations of key plants in the peak times for power usage from 10 a.m. to noon and 5 p.m. to 7 p.m.

Hyundai Motor, the nation’s largest automaker, plans to turn off office heaters during the peak times, while turning them off for the day 30 minutes earlier than usual.

Hyundai Steel also plans to cut use of its electric furnace during the peak times.

Companies also join the energy-saving initiative to keep the indoor temperature of their office buildings at below 20 degrees Celsius during the wintertime.

The nation’s power demand management has been challenged by the extended cold spell from the beginning of December. It is the third time since November that the Korea Power Exchange has issued the watch warning.

As further severe cold spells are expected this winter, the ministry closely monitors power demand trends on a daily basis to avoid a possible blackout, officials said.

By Seo Jee-yeon (jyseo@heraldcorp.com)