A risk assessment should be done when:
there is uncertainty about how a hazard may result in injury or illness
the work activity involves a number of different hazards and there is a lack of
understanding about how the hazards may interact with each other to produce new or
greater risks
changes at the workplace occur that may impact on the effectiveness of control measures.
A risk assessment is mandatory under the WHS Regulations for high risk activities such as
entry into confined spaces, diving work and live electrical work.