This paper presents the probabilistic model of redundant system with common cause failure (ccf), logic failure and human error. The various states of the system are represented by Markov-model. As the number of states grows in size, it is tedious to solve the system state equations by Laplace inverse transform. This paper presents a new approach using standard numerical methods to solve such problems. The numerical results obtained in Ref. B. S. Dhillon and S. N. Rayapati, Common cause failure and human error modelling of redundant systems with partially energized standby units, Reliab. Engng. 19, 1-14 (1987) for redundant system with common cause failure and human error compare well with the results obtained with this new approach.