For electoral purposes, the country is divided into areas known as constituencies, each of which elects either three, four or five TDs. Under the Constitution there must be at least one TD for every 20,000 to 30,000 people. A candidate to become a TD must be an Irish citizen and over 21. Members of the judiciary, the Garda Síochána and the Defence Forces are disqualified from membership of the Dáil.
Feb 26 2015, 12:01 AM
There are 166 TDs in the 31st Dáil. The next general election will elect 158 TDs, a reduction of 8, following the passing of the Electoral (Amendment) (Dáil Constituencies) Act 2013.
Source of Reference:- Wikipedia - Teachta Dala