In this study, investigation on risk assessment and underlying root causes of accident was conducted in a power services company within the Port Harcourt metropolis of Rivers State, Nigeria. Both primary and secondary data were used. Primary data was obtained with the aid of a structured questionnaire on the responses on fifty-four persons consisting of office, maintenance and field workers. Descriptive statistics (i.e. mean and frequency distribution) was used in analysing the data. Results show that employees were exposed to workplace hazards such as physical (noise/heat); chemical (vapour/fumes) and ergonomic (stress/sprain). The Human Factor Accident Classification System (HFACS) was able to identify human error as a major cause of accident it the workplace. Unsafe acts of workers (57.8 %), preconditions for unsafe acts (76.7 %), unsafe supervision (69.4 %) and organizational influence (62.3%) were rated by the responded.

Keywords : Risk assessment, human error, unsafe acts, accidents, root causes