Unprecedented power blackouts struck Seoul and many parts of the nation Thursday, causing enormous inconvenience to the public and temporarily disrupting industrial and commercial activity in the affected areas.

The unexpected power outages, the first of their kind in Korea, paralyzed banks, offices, stores and schools in Seoul, Busan and other cities across the nation for hours. In Seoul alone, there were about 1,000 cases of people trapped in elevators. Traffic lights went out in many places, worsening congestion during the rush hour.

Industrial complexes in many regions of the nation also suffered power shortages. They included the steel industry complex in Pohang on the southeastern coast, the auto parts cluster in nearby Ulsan, the electronics industry hub in Gumi, and the machinery complex in Gimhae, near Busan.

However, the damage was limited as the regional power outages lasted 30 minutes and many companies had their own emergency power generating equipment.

According to Korea Electrical Power Corp., the cause of the mess was a sudden spike in electricity consumption that overshot the supply capacity. The grid operator said power demand surged Thursday afternoon due to the ongoing unseasonable heat wave.

KEPCO said it was forced to implement rolling blackouts as the reserve power capacity fell to as low as 1.48 million kilowatts at around 3 p.m. Under the power utility’s manual, rolling blackouts are implemented when the reserve capacity reaches the “serious” level of below 1 million kilowatts.

But KEPCO justified its decision by saying that if action is taken after the reserve capacity has fallen below the alert level, it is already too late. In this regard, it said, the manual needs change.

On Thursday, peak electricity consumption hit 67.26 million kilowatts, much higher than the 58.75 million kilowatts recorded on the previous day. But it was not particularly high compared with this year’s peak demand of 72.19 million kilowatts recorded on Aug. 31. The problem was that a number of power plants were undergoing maintenance.

Since Sept. 9, KEPCO has put a total of 23 power plants, which account for 8.34 million kilowatts or 11 percent of the nation’s maximum power generation capacity of around 79 million kilowatts, under maintenance. It judged that the summer heat has subsided.

But it was wrong. The thermometer began to go up this month, boosting power consumption to above 60 million kilowatts. On Thursday, demand for power surged as the heat wave gripped much of the nation.

Faced with unexpected surge in power consumption, the grid operator cut off the power supply to prevent the collapse of the grid from too much demand. As a result, a total of 2.12 million homes throughout the country were affected.

KEPCO normalized power supply around 8 p.m. by activating some of the power plants under maintenance. But it inflicted damage on businesses and caused inconvenience to people by implementing blackouts without any prior notice. Companies that have suffered damage due to the grid operator’s failure to alert them in advance are expected to file suits against it.

The power company could have avoided the disaster had it heeded the weather forecast by the Korea Meteorological Administration that a heat wave could hit the country after the Chuseok holiday, which ended Tuesday.

Now KEPCO should turn the debacle into a teaching moment. It should always remember the maxim that the danger comes when you least expect it. The public should also use it as a learning moment. It was an expensive reminder of the importance of energy conservation.

The Japanese set a good example of electricity conservation following the Fukushima nuclear plant meltdown in March. It is a shame that Korea suffered a blackout, which has not occurred in Japan even under a severe power shortage. To avert the recurrence of another such debacle, we all need to step up power-saving efforts.