I'm the only IT administrator at a company building a new facility, including a main MDF and two IDFs. The IDF racks already have battery backups, but I need to choose a UPS and power layout for the main rack.
The rack will contain a dual-CPU Dell server with two Intel Xeon Gold 5315Y processors, three Hyper-V virtual machines, and 8–10 drives; four 48-port PoE switches; approximately 21 UniFi cameras, six wireless access points, and 15–20 PoE phones; dual firewalls; a network video recorder with 12–16 drives; and possibly a backup appliance, modems, and other equipment.
The initial plan includes standard outlets and a dedicated 20-amp circuit. Since construction is still underway, I may be able to request a 208-volt, 30-amp locking outlet instead. I'm fairly inexperienced with calculating power requirements and would appreciate advice on the required UPS capacity, runtime, voltage, PDU arrangement, and suitable models. I'm also unsure how to handle smaller 120-volt devices such as modems, cellular failover equipment, sensors, and other equipment that uses ordinary two- or three-prong plugs.
4 Answers
Start by measuring or getting the rated input power for every device, then add the totals with some headroom. Don’t size the UPS from the server’s CPU specification alone—the PoE switches, cameras, storage, and NVR may be a significant part of the load. A 120-volt, 20-amp circuit is probably too limiting for this rack, especially once you account for continuous-load rules and desired expansion.
Since the building is still being designed, a 208-volt, 30-amp circuit with a locking connector would give you much more practical capacity. A double-conversion rack UPS such as an Eaton 9PX 2000VA-class unit or a Vertiv/Liebert GXT5 is a reasonable starting point, but confirm the measured load before choosing the final size. Add external battery modules only if you need extended runtime; for many sites, the UPS only needs to bridge short outages or allow an orderly shutdown.
Vertiv/Liebert GXT5 units are worth considering, and Eaton’s 9PX line is also commonly used for this kind of rack. Look at watts as well as VA, and choose a unit that leaves comfortable capacity rather than running near its limit. Runtime depends heavily on the load and battery configuration, so decide whether you need only a few minutes for shutdown or several hours during an outage.
For a new facility, it’s also worth planning the physical installation now: a properly grounded rack, vertical PDUs, adequate front and rear clearance, cable management, and independent cooling for the equipment room if possible. UPS power cannot compensate for an overheated server room.
A clean arrangement would be one appropriately sized 208-volt UPS feeding a rack PDU, with dual-corded servers and switches connected to redundant power paths where available. If you can install two circuits or panels, you can place one power supply on each path for better resilience.
For 120-volt equipment, you usually don’t need a second UPS. Many rack UPS systems provide 120-volt outlets through the PDU, or you can use a listed step-down or distribution solution designed for that UPS. Check the UPS output voltage and receptacle types carefully—don’t use an improvised adapter or overload a convenience outlet. For important single-cord devices, an automatic transfer switch can combine two power sources safely and provide failover.
That clears up my main concern. I was unsure whether moving to a 208-volt UPS meant that ordinary 120-volt modems and sensors would need their own UPS. I’ll verify the output options and use the correct PDU or transfer equipment instead of relying on adapters.
Before buying anything, ask the electrician or equipment vendors for the expected wattage of the server, storage system, switches with their PoE load, cameras, and NVR. The PoE budget is especially important because four switches can consume far more when all cameras, access points, and phones are active. Also check whether each device accepts 100–240 volts; most enterprise servers and switches do, but small modems and miscellaneous equipment may only accept 120 volts.
A UPS is not a substitute for a generator or long-term cooling plan. If outages can last a while, design for graceful shutdown or generator-backed power rather than trying to buy enough batteries for the entire building.
I’m going to ask the contractor whether the 208-volt, 30-amp circuit can be added. Power calculations are still new territory for me, so I’ll start by collecting the actual draw for each device.