Power blackouts (outages) are a common occurrence in Kenyan households. They affect people's livelihoods, and damage their property (household electrical items). We explore the role of GridAlert-A sensor-based technology we designed-in monitoring power blackouts. We worked with local technicians to design GridAlert's housing and integrate GridAlert with Kenya's electricity infrastructure. Then, we used interview, observation, diary, and data logging methods to understand 18 households' experiences using the system. Our findings provide insights for using sensor-based technology to monitor power usage and blackouts in Kenyan households. We also present participants' thoughts about GridAlert's housing, and about how it influenced their actions when using the system. We use these findings to discuss design insights for power monitoring systems, and to offer new perspectives on the role of technology in monitoring blackouts in Kenyan households.