These are extracts from the Human Ethics Committee Guidelines:
5.2 Research and teaching activities which do not require approval
5.2.1
From the start of any research that involves human subjects, it is always important for researchers to consider whether ethical approval is required. The following should be read in that light.
5.2.2
Ethical approval is not required for:
(a) Exploratory research consisting solely of preliminary interaction or discussion where the exact research aims have not yet been formulated. If a researcher later wishes to use data collected at an exploratory stage, retrospective consent should be obtained.
(b) Research in which the investigator is the subject of his or own research, and where no physically dangerous or emotionally hazardous procedure is involved.
(c) Some interviews which merely seek non-sensitive factual information as set out in section 5.6.
(d) Research involving existing publicly available documents or data (or, for example, analysis of public archival records).
5.2.3
Research involving oral or written questionnaires may fulfill the criteria set out in paragraph 5.5.2. In such cases a single application should be made to the head or manager who has the responsibility to ensure that the research undertaken observes the ethical principles set out.
...
5.6 Procedures regarding interviews
5.6.1
(a) Ethical approval is always required where the interviewee's name will be used as the source of data or of a quotation. Interviews where the interviewee's name will be kept confidential also require approval. The only exceptions are: (i) where the object of the interview is merely to seek non-sensitive factual information (e.g. requests for statistical information or information about services from public agencies); (ii) Informal discussions with colleagues, family and friends. Where the information is to be attributed or used in a formal sense, ethics approval must be obtained.
...