Management tasks in datacenters are usually executed in-band with the data plane applications, making them susceptible to faults and failures in the data plane. In this paper, we introduce power line communication (PLC) to datacenters as an out-of-band management channel. We design PowerMan, a novel datacenter management network that can be readily built into existing datacenter power systems. With commercially available PLC devices, we implement a small 2-layer prototype with 12 servers. Using this real testbed, as well as large-scale simulations, we demonstrate the potential of PowerMan as a management network in terms of performance, reliability, and cost.