Both distribute power downstream of the UPS — but a Remote Power Panel is a room-level circuit breaker panel, and a Power Distribution Unit is the rack-level device that actually terminates in outlets a server plugs into.
Power leaving a UPS still has to travel through several stages of distribution before it reaches a GPU server's power supply, and two of the most commonly confused stages are the RPP (Remote Power Panel) and the PDU (Power Distribution Unit). An RPP is essentially a circuit breaker panel positioned out on the data hall floor, closer to the load than the central switchgear, splitting a large UPS-fed feeder into many smaller branch circuits — each one typically feeding a single rack or a small group of racks. A PDU is the device actually mounted in or beside that rack, taking one of those branch circuits and breaking it down further into the individual outlets that server power cords plug into, often with local monitoring, remote outlet switching, and metering per outlet or per circuit. RPPs live in the room; PDUs live in the rack. Confusing the two — especially when sizing circuits or troubleshooting a tripped breaker — sends an engineer looking in the wrong physical location entirely.
Power distribution in a data hall is a fan-out problem: a UPS plant produces a small number of very large feeders, and a single server needs a small, individually protected outlet. The RPP is the stage that takes one of those large feeders and splits it into dozens of moderate branch circuits — commonly sized at 30A, 50A, or 60A at 208V for GPU racks — one circuit typically routed to each rack or small cluster of racks. The PDU is the next stage down, living inside or beside that rack, taking a single branch circuit and splitting it further into the actual outlets a server plugs into, often adding per-outlet metering, remote switching, and sometimes automatic transfer between A/B feeds for dual-corded servers. Knowing which stage you're at matters operationally: a tripped breaker traced to "the RPP" could take down an entire rack row, while a tripped breaker traced to "the PDU" is isolated to outlets on that one strip.
The term "PDU" is used loosely across the industry and genuinely refers to different equipment depending on context. A "floor-mounted PDU" (sometimes called a power distribution unit in the traditional electrical-room sense) is a larger cabinet containing a transformer and panelboard, functionally very similar to what this article calls an RPP — some facilities use "PDU" for that room-level equipment and reserve "rack PDU" or "rPDU" specifically for the rack-mounted outlet strip. Always confirm which piece of equipment a drawing, spec, or conversation means by "PDU" — a floor-mounted PDU/RPP and a rack PDU sit at completely different points in the distribution chain and have very different fault, capacity, and troubleshooting implications. This article uses "RPP" specifically for the room-level breaker panel and "PDU" specifically for the rack-mounted outlet device to keep the two distinct.
Explains the difference between an RPP (Remote Power Panel), a room-level breaker panel that splits a UPS feeder into branch circuits for individual racks, and a PDU (Power Distribution Unit), the rack-mounted device that breaks a branch circuit down into the individual outlets servers plug into.
A Remote Power Panel is essentially a circuit breaker panel positioned on the data hall floor, fed by a large UPS output feeder and splitting it into many smaller branch circuits — typically 30A, 50A, or 60A at 208V for modern GPU rack loads. Each branch circuit routes across the floor (via cable tray, conduit, or busway) to a single rack or a small group of racks. RPPs are a facility-level distribution asset, and their breakers protect the wiring between the panel and the rack.
A rack Power Distribution Unit (rPDU) mounts inside or beside a single rack, receiving one branch circuit from the RPP and breaking it further into the individual C13/C19 (or similar) outlets that server power cords actually plug into. Modern rack PDUs commonly add per-outlet or per-circuit metering, remote outlet switching for reboot-without-a-truck-roll capability, and — for dual-corded servers — automatic switching between redundant A/B feeds.
The term "PDU" is used inconsistently across the industry: some facility teams use "PDU" for the larger floor-mounted transformer/panelboard equipment that this article calls an RPP, reserving "rack PDU" or "rPDU" for the smaller rack-mounted device. Others use "PDU" exclusively for the rack-mounted unit, as this article does, and "RPP" or "power panel" for the room-level equipment. Confirming which specific piece of equipment a drawing or spec means by "PDU" avoids real troubleshooting and capacity-planning mistakes.
High-density AI/GPU racks routinely draw far more current per rack than legacy enterprise racks, which pushes RPP branch circuit sizing (and PDU capacity) well beyond older 20A/120V norms into 3-phase 208V or even higher-voltage distribution. Getting the RPP-to-PDU capacity chain right — confirming the RPP breaker, the branch circuit conductor ampacity, and the PDU's own rated capacity all support the rack's actual nameplate and continuous load — is one of the most common places electrical designs undersize in a GPU rack retrofit.
In modern data center design, yes — nearly every rack gets at least one (often two, for A/B redundancy) rack-mounted PDUs so per-rack power can be metered, monitored, and remotely managed independently of neighboring racks.
Yes, especially for redundant (A/B) power designs, where a rack has two PDUs, each fed from a physically separate RPP (ideally on separate UPS/utility paths), so a fault in one path doesn't affect the other PDU's outlets.
An overhead busway is an alternative to conduit-and-panel branch circuit distribution — a continuous prefabricated bus bar run above rack rows that individual rack "tap-off boxes" plug into, feeding the rack PDU. Busway systems are increasingly common in high-density AI/GPU halls because they make adding or relocating rack circuits much faster than pulling new conduit runs from an RPP.
Yes — even a simple rack PDU is genuinely distributing power, since it takes one incoming circuit and fans it out to many independently protected (fused or breakered) outlets, exactly the same fan-out function the RPP performs one level up, just at rack scale instead of room scale.