This paper presents an efficient technique for placement and routing of sensors/actuators and processing units in a grid network. Our system requires an extremely high level of robustness and efficient power optimization techniques. By modeling the faults, we evaluate the probability of having failures in network. Then we study two problems of placement and routing in the sensor networks such that the fault tolerance is maximized while the power consumption is minimized. We develop efficient methodology to address these problems and perform both placement and routing simultaneously. This ensures that the solution is a lower bound for both problems. We evaluate the effectiveness of our proposed techniques on a variety of benchmarks. Categories and Subject Descriptors B.8.0 [Performance and Reliability]: Fault-tolerance and power optimization in grid sensor networks. General Terms Algorithms, Management, Performance, Design, Reliability. Keywords Sensor Networks, Placement, Routing, Fau...