New Delhi, July 31 - Many parts of the capital are expected to go dark as the clock strikes 8.30 p.m. Friday with Delhiites planning to voluntarily switch off non-essential lights for one hour to save power.

The initiative comes on the lines of a global Earth Hour observed March 28 when Delhi managed to save a whopping 10,000 MW of power in an hour.

Taking a cue from the event, the Delhi government decided in April to observe Earth Hour quarterly on the last working day of every third month.

The government has asked 2,000 residents welfare associations (RWAs), 2,000 students in school ecological clubs and market associations to join the campaign.

Residents have also pitched in and are sending SMSes and email messages urging people to join the campaign to save power by turning off non-essential lights from 8.30 p.m. to 9.30 p.m.

'My friends and I are sending email and text messages to relatives, friends and acquaintances asking them to switch off lights during Earth Hour,' said Charu Gupta, a college student living in Malviya Nagar.

Many communities have been formed on social networking site Facebook, urging people to observe Earth Hour.

Uzzwal Madhab, who started the Earth Hour 2009 group on Facebook, said: 'I welcome the Delhi government initiative and we have been asking people to join hands in saving power.