Different voting rules are already catching Wanganui voters out with a number of votes being declared invalid because they have been filled out incorrectly.
The problem has occurred with voting for the Whanganui District Health Board.
The WDHB uses the single transferable voting (STV) system which means electors must list their preferred candidates with a number rather than a tick.
But Wanganui electoral officer Noeline Moosman said yesterday that some papers had already been returned and voters had used a tick rather than a numeral for the DHB candidates.
A tick is used for the Wanganui mayoralty, district council and regional council elections. The councils use the first past the post (FPP) voting system with electors ticking the box beside the name of their preferences.
But Mrs Moosman said when voting for WDHB members, voters must number their preferred candidates in the order they want to see them elected.
She said with the STV system, if a voter gives a candidate a "1", then that voter is indicating that the candidate is their first choice.
Voting papers were posted out last week but already a number of papers for the DHB elections have been declared invalid. Mrs Moosman said under FPP voters tick only one preferred candidate out of three for the Wanganui mayoralty, 12 candidates out of a total of 36 for the Wanganui District Council election, and tick two candidates out of three for the regional council election.
The WDHB election appears in a light yellow box on the voting paper, and carries clear instructions above about how the STV system works.
She said it was obviously important for people to read the instructions carefully for all four elections, paying particular attention to the instructions for the WDHB voting paper.
To date, 2875 voting documents have been returned, which is 9.27 per cent of the eligible voters on the roll.
The STV process had earlier been highlighted as a trap by two current members of the district health board.
Allan Anderson and Ray Stevens had been asked by the board to prepare a paper on STV and it is expected to be tabled at the board meeting tomorrow.
In it they said an "alarming number" of voting papers ruled invalid in elections in 2007 and again in 2010. In 2007 1747 - nearly 7 per cent - of votes were disallowed because voters had incorrectly filled in the voting papers.