The electrical failure occurred in an apartment complex, Eunma Town, which consists of some 4,400 units. The complex was built in the 1970s.
A similar incident took place in Goyang, Gyeonggi Province, where 580 units in an apartment complex lost electricity.
“We will do our absolute best to assure households and firms through solid management of the power supply and demand,” said Prime Minister Lee Nak-yon on Thursday, ordering civil servants to pay closer attention to the nation’s electricity situation.
According to Lee, the Korean government had previously predicted that the maximum electricity load would likely reach 88.3 million kilowatts this year.
Due to the prolonged heatwave, however, power demand has already surpassed 90 million kW, he added.
Still, Lee said there is no need to be concerned, as the government has additionally secured power reserve of some 6.81 million kW.
As of Thursday morning, some 29 Koreans have died from heat-related illnesses, while 2,300 have sought medical attention for health conditions caused by the hot weather.
"I'm feeling dizzy all the time, even though I'm rarely outdoors," said Jang Ji-hye a 28 year-old professional in Seoul.
"Spending five minutes outside makes you feel like you are going to throw up in any minute."
South Korea hit an all-time highest temperature of 40.7 degrees Cesius on Wednesday. The ongoing heat wave has been plaguing the nation since early July.
Daytime highs reached 40.3 degrees Celsius in Hongcheon, Gangwon Province, marking the highest level since 1907, the year country started recording weather data, authorities said.
A series of rather unusual events have been attributed to the hot weather in the country throughout the last month.
In Gangneung, Gangwon Province, a chick was hatched from an egg last month, without a mother hen or brooder lamp -- thanks to the blazing heat and continued tropical nights.
Also last month, a glass window fell from the eighth floor of a department store in Seoul, as the window’s silicone sealant reportedly melted in the blazing heat. A similar incident took place in one of the police stations in Gwangju.
"I can't imagine what it would be like in the year of 2050, if the weather is this unbearable now," said Park Jin-kyu, a 53-year-old taxi driver in Seoul.
"I feel sorry for the next generation."