The power cuts also affected water supplies and forced many to sleep in their air conditioned cars as the mercury reached 48 degrees Celsius (118 degrees Fahrenheit).
Angry residents blocked roads and protested outside power distribution companies on Friday, demanding government action and saying that helplines set up to take complaints were not functioning.
Traffic lights and universities were not spared from the cuts and even New Delhi's main international airport had to rely on a back-up power supply.
New Delhi's Chief Minister Sheila Dikshit said she was "monitoring the situation," while government officials blamed neighbouring states for using too much electricity from the shared power grid.
Water supplies have also been hit by this year's delayed monsoon season.
Annual monsoon rains failed to appear two weeks ago, prompting concerns about the impact on water supplies and agriculture as lakes run dry after a long, hot summer.
Since April more than 100 people have died in a heatwave roasting mostly northern and eastern India.
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Angry residents blocked roads and protested outside power distribution companies on Friday, demanding government action and saying that helplines set up to take complaints were not functioning.
Traffic lights and universities were not spared from the cuts and even New Delhi's main international airport had to rely on a back-up power supply.
New Delhi's Chief Minister Sheila Dikshit said she was "monitoring the situation," while government officials blamed neighbouring states for using too much electricity from the shared power grid.
Water supplies have also been hit by this year's delayed monsoon season.
Annual monsoon rains failed to appear two weeks ago, prompting concerns about the impact on water supplies and agriculture as lakes run dry after a long, hot summer.
Since April more than 100 people have died in a heatwave roasting mostly northern and eastern India.
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