Polling Day for a General Election is a public holiday, and polling hours are from 8am to 8pm. That should give voters enough time to cast their vote.
If you are required to work and your work hours coincide with the polling hours, you should request time-off from your employer. The law requires employers to give employees, who are voters, a reasonable amount of time to vote.
Voting is also compulsory. If you fail to vote, your name will be taken off the Registers of Electors after the election. But you can apply for your name to be restored to the Registers should you wish to vote in future elections.
Do take note that you must vote in person. You cannot authorise another person to vote in your place.
Source: ELD FAQ
This article is accurate as of Aug 2015.