Kandelaars was born in Australia after his Dutch parents Leo and Nelly left the Netherlands after World War II.
He was also a director on the Board of Telstra Super, Australia's largest corporate superannuation fund with over $11 billion in funds under management and was a member of its Audit, Risk and Management Committee and its Remuneration Committee.
He gained Labor preselection to the Legislative Council in a joint sitting of the Parliament of South Australia on 13 September 2011 to replace outgoing MLC Paul Holloway.
Kandelaars has expressed dismay at prejudice towards migrants in South Australian society and condemned Liberal Senator Cory Bernardi for his support of Dutch far-right politician Geert Wilders.
Kandelaars resigned from parliament on 17 February 2017 to care for his sick wife, which created a casual vacancy and subsequent appointment.