Some 16 240 voters intend casting their votes at the 124 South African missions overseas on Wednesday.
Of these, 7427 voters are registered to vote at the South African mission in London, making it the largest polling station in the elections, said the Independent Electoral Commission (IEC).
The largest voting station in South Africa is at Joubert Park, Johannesburg. The IEC was not able to give the exact number of registered voters at Joubert Park but suggested the figure was around 3000 to 4000.
The second largest overseas polling station is in Canberra, Australia, with 1235 registered voters, then Dubai in the United Arab Emirates with 900 registered and Wellington, New Zealand with 410.
The Hague in The Netherlands has 378 registered voters and Dublin, Ireland has 360.
The voting stations with the lowest number of voters are Asmara (Eritrea), Suva (Fiji), Ramallah (Palestine), Bujumbura (Burundi) and Trinidad & Tobago (Port of Spain) with only one voter each.
To ensure both the secrecy and legitimacy of overseas votes, the IEC has set up a two envelope system.
Once a voter at an overseas mission has cast their vote in secret it is placed in an unmarked envelope and sealed.
This unmarked envelope is then placed in another envelope with the voter's name, ID number and voter district number.
These envelopes are then placed in a ballot box which is sealed.
When it is opened on election day, the details on the marked envelope are checked against the voters' roll and if there is no irregularity, the unmarked envelope is placed in the ballot box.
This ensures the vote is anonymous when the ballot is then counted.
Overseas voters must be registered and produce their ID and passport to be allowed to cast their vote.
Voting stations at South African missions abroad will be open from 7am to 7pm.
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