We're building a new facility and updated the electrical plan to provide two dedicated rack circuits: one 208V/240V circuit and one 120V 30A circuit. The MDF will contain four UniFi Pro 48 PoE switches, roughly 26 cameras, seven access points, about 20 desk phones, two UDM Max firewalls in an HA pair, a dual-CPU Dell server with redundant 600W power supplies, a UniFi Enterprise NVR with redundant power supplies, two internet modems, and a few miscellaneous devices.
My original plan used mixed-voltage power for the redundant server and NVR supplies, but I learned that this was not the best approach. I'm now planning to use two APC SRT3000RMXLT-NC UPS units, with one paired with a 120V transformer so both systems can use the same 208V infrastructure. One UPS will primarily support the switches and primary server/NVR supplies, while the other will provide redundant power to the secondary server/NVR supplies and other equipment. Each UPS will have an external battery pack.
The calculated worst-case load approaches the limits of a 3000VA UPS, but that assumes every PoE port is drawing maximum power. In practice, only around 40–50 ports are expected to be active, and normal utilization should remain well below the maximum. The refurbished units, including new batteries, would cost less than $4,500 compared with approximately $10,000–$12,000 for a comparable new setup.
Does this seem reasonable from a capacity and redundancy perspective? Would you change anything while keeping the budget near the same range?
4 Answers
The overall approach sounds solid, but be strict about battery maintenance. Even if the UPS rarely runs on battery, plan on replacing the batteries on a defined schedule—around three years is a sensible interval for these units. Also confirm that the refurbished seller is testing the UPS electronics, not just installing new battery cartridges.
The four 48-port switches may be more capacity than you currently need if only about 50 devices will be connected, so it’s worth checking the expected growth over the design life of the facility. If the extra ports are for future expansion, document that assumption and confirm the rack, power, cooling, and uplink capacity can support it. Otherwise, fewer switches could reduce both UPS load and long-term replacement cost.
Two UPS units improve resilience, but they don’t automatically create seamless failover for equipment that has only one power supply. For the server and NVR, the redundant supplies should be connected to separate UPS systems and circuits. For single-cord devices, consider appropriately rated automatic transfer switches or redundant power hardware. Also make sure the runtime is long enough for an orderly shutdown, and configure monitoring so nonessential services can shut down first.
Using two UPS units on the same voltage is a much cleaner design than splitting redundant power supplies across 120V and 208V. I’d still verify the actual watt load, power factor, startup transients, and the UPS output connector requirements rather than relying only on the equipment’s nameplate ratings. Leave meaningful headroom instead of designing around the absolute maximum capacity.
That’s the direction I’m taking now. The original load estimate was intentionally conservative and assumed all PoE ports were at maximum draw, which won’t happen in this installation. Normal usage should be well below the UPS limits, with the external batteries providing additional runtime.
That’s one reason I prefer two UPS units instead of depending on a single unit. I’ve had a UPS fail unexpectedly before and don’t want to be forced to bypass it with basic surge protection while trying to restore service.