CHENNAI: The Election Commission has ordered by-election to Dr Radhakrishnan Nagar constituency in Chennai on April 12. It has been necessitated following the death of former chief minister J Jayalalithaa. "The commission has decided to use electronic voting machines in the by-poll. Adequate numbers of EVMs have been made available and all steps have been taken to ensure that the polls are conducted smoothly with the help of these machines," the commission said. Meanwhile, the model code of conduct comes into force with immediate effect. Also, the commission has decided that the voter's identification will be made mandatory at the time of poll.