It is the latest drastic measure to alleviate a severe electricity crisis which President Nicolas Maduro and his government blame on the El Nino weather phenomenon that causes drought.
Critics say it's the result of years of economic mismanagement.
Luis Motta Dominguez, minister for electric power, made the announcement during a televised broadcast and said further details would be released in the coming days.
Maduro is under growing pressure from the center-right opposition, which vowed to oust him when it took control of the legislature in January after winning elections, blaming him for the crippling economic crisis.
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Maduro blames the collapse on an "economic war" by capitalists.
Last week, his government said it was shifting its time zone forward by 30 minutes to save power.
Other measures include giving government workers an extra day off each week for the next two months, and Maduro has urged Venezuelan women to stop using their hairdryers.
"The greatest power consumption is residential," Motta said, speaking at the Guri hydroelectric plant.
Maduro said yesterday that residential energy-saving targets had not been met, necessitating the rationing that "will save the Guri" from collapse.
Water levels in the country's 18 hydroelectric dams have dropped to dangerously low levels, and citizens regularly suffer blackouts and water rationing.
Venezuela has the world's largest proven oil reserves, but the government has resisted using crude to generate electricity, calling it inefficient.
He has also ordered shops and hotels to ration electricity, obliging them to generate their own power for several hours a day.
Shopping centers have cut back their hours since that plan was introduced.