A major power failure plunged large parts of Pakistan's Karachi into darkness since early Friday morning.

About 90 percent of Karachi, a city of 23 million citizens, was hit by a huge power cut after a 500KV transmission line supplying electricity to the metropolis tripped near Jamshoro, bringing much of normal life in Pakistan's largest city to a standstill, Pakistan's GEO News reported.

The third major outage of the country's dilapidated electricity grid within a month forced shops, hospitals and businesses to turn to back-up generators as the lights went out, including those in the provincial assembly. Trading at the stock market was not interrupted by the breakdown.

According to K-Electric, the main electricity supplier for the city tripped near Jamshoro, resulting in suspension of power supply to more than two-third of Karachi.

K-electric said high levels of humidity caused the transmission line to trip.

A 72-inch diameter water pipeline burst at the Dhabeji pumping station after the power breakdown due to excess back pressure, Karachi Water and Sewerage Board (KWSB) executive engineer Lal Baksh Samoon told Geo News.

The pipeline burst also caused suspension of water supply to Karachi. According to Samoon, it could take up to 48 hours for the pipeline to be repaired.