As cable broadband networks evolve to meet capacity and performance expectations – pushing legacy functions outward toward the edge – critical facilities are challenged to maintain reliability, forcing operators to revisit their power architectures. The ever-growing reliance on high-speed network connectivity are driving the transition to distributed access architectures, with Remote-PHY Devices (RPDs) in edge nodes taking on much of the work that had been traditionally performed in critical facilities. High-density virtual CMTS (vCMTS) and edge gateway server racks are replacing legacy equipment in the critical facility, increasing network capacity and performance, but at the cost of increased energy consumption and associated thermal loading. Heating Ventilation and Air Conditioning (HVAC) systems, not traditionally backed up by batteries, may need to be reconsidered as a critical load. As described in SCTE 184, “Modern equipment densities can overheat an environment in less than an hour without adequate cooling making any additional installed capacity unusable.” At the same time, external threats to the utility grid – extreme weather events, electric vehicles, heat pumps and air conditioning units – are leading to more frequent and longer utility outages, adding to grid instability, and placing more reliance on the effectiveness of the power backup system. This combination of increasing grid instability, reliability expectations and added thermal load may drive operators to revisit their existing critical facility (CF) power architectures. In addition to increasing reliability, operators are focused on meeting their corporate sustainability goals toward reducing overall energy consumption and reliance on fossil fuel sources. Improving power efficiencies in the critical facilities and introducing distributed energy resources can help these efforts. A nanogrid architecture can allow the use of distributed energy resources (DERs) such as wind or solar to supplement utility power, allowing operators to realize additional cost benefits by avoiding peak usage utility rates or selling power back to the grid. In this paper we will: 1) Walk through a complete critical facility outage with today’s architectures. 2) Identify threats to critical facility reliability. 3) Look at how changes to critical facilities will lead to additional reliability challenges. 4) Explore nanogrid architectural steps that could be implemented to increase reliability. 5) List additional benefits from moving to the proposed nanogrid architecture. 6) Anatomy of a Critical Facility Blackout.