FRC PDH: The Power Distribution Hub Explained (Channels, Fuses & Wiring)

The Power Distribution Hub (PDH) is the electrical spine of a modern FRC robot. Every motor controller, the roboRIO, the radio, your pneumatics, and every sensor rail ultimately pull their current through it. Get the PDH right and the rest of your wiring is calm and debuggable; get it wrong and you spend elimination matches chasing brownouts and popped breakers you can't see. The PDH is REV Robotics' part REV-11-1850, the power-distribution board in the REV ION control-system family, and it replaced the CTRE Power Distribution Panel (PDP) as the default board most teams reach for.

This guide walks through exactly what the PDH does, its full 24-channel layout, how to pick the right breaker for each device, how to wire it cleanly, what the switchable channel is for, and how its CAN telemetry helps you diagnose problems mid-competition. If you're brand new to the electronics, skim the FRC control system explained first so the roboRIO/radio/PDH relationship is clear before you dive into channel assignments.

What the Power Distribution Hub is

The PDH takes a single high-current feed from your 12V battery and splits it into many individually protected outputs. Instead of running every device straight off the battery (a fire hazard and impossible to fuse), you land one heavy pair of wires into the PDH, protect that feed with the robot's main breaker, and then break power out into 24 channels — each one with its own fuse or circuit breaker sized to the device on it.

That protection is the whole point. If a drive motor stalls and draws far more current than its wiring can carry, the breaker on that channel trips instead of cooking the wire, browning out the whole robot, or damaging the battery. The PDH also carries a CAN connection back to the roboRIO, so it isn't just a dumb splitter — it reports per-channel current, total draw, and battery voltage in real time.

Where the PDH sits in the control system

The power chain on a legal FRC robot is short and strict:

1. Battery (12V SLA or equivalent) →
2. Main breaker (120 A) →
3. Power Distribution Hub →
4. every device, each on its own fused/breakered channel.

The roboRIO, the radio, motor controllers, the Pneumatic Hub — all of it hangs off the PDH's channels. The PDH is the one board that touches nearly everything, which is exactly why a clean, labeled PDH makes the difference between a five-minute fix at competition and a dead robot. For the full battery-to-breaker story, see the FRC battery guide and the how to wire an FRC robot walkthrough.

Safety first: Never work on PDH wiring with the battery connected. Disconnect the battery at the Anderson connector and, ideally, flip the main breaker before you touch a terminal. A 12V FRC battery can push hundreds of amps into a short — enough to melt a wrench or a ring.

The channel layout: 24 channels, three flavors

The PDH exposes 24 channels total, numbered 0–23, split into three groups. This is the single most important table to internalize:

That's 20 big channels plus 4 small ones (three always-on, one software-switchable). The board also has an onboard LED voltage display so you can read battery voltage at a glance, and it operates across a 4.7–18 V range, which matters during brownout recovery.

High-current channels (0–19)

Channels 0 through 19 are your workhorses. Each one supports up to 40 A and accepts an ATO/ATC-size fuse or, far more commonly, an ATO-size auto-resetting circuit breaker (the yellow/colored Snap-Action-style breakers you see in every FRC electrical board). Twenty of these is a lot — enough for a swerve drive (8 motors) plus a full complement of mechanism motors without ever touching the low-current bank.

Use these for anything with a real motor behind it: drivetrain motors, arm and elevator motors, intakes, shooters, climbers. If a device draws more than 15 A even briefly, it belongs on a high-current channel.

Low-current channels (20–22)

Channels 20, 21, and 22 are rated for 15 A continuous and 20 A peak (a single channel can sustain 20 A for about five minutes). They take ATM/APM-size ("mini") fuses. These exist for the smaller, always-on loads that don't need 40 A of headroom: the roboRIO, the radio's regulated supply, small electronics, and the Pneumatic Hub (which the low-current channel supports up to 20 A).

The switchable channel (23)

Channel 23 is a low-current channel with a twist: it can be switched on and off in software over CAN. Same 15 A rating and ATM/APM fuse as the other low-current channels, but you get discrete on/off control of whatever hangs off it — most commonly LED indicators, signal lights, or an accessory you want to cut power to without a physical relay. More on how to drive it below.

Choosing the right breaker for each device

The rule is simple but easy to get wrong: the breaker protects the wire, not the device. You size the breaker to the smallest wire on the channel, and you keep it at or below the channel's rating. A 40 A breaker feeding 22 AWG signal wire is not protection — it's a fuse-shaped fire starter, because the wire will fail long before the breaker trips.

Here's a practical starting map for a typical robot:

Match the breaker to the motor's spec, not to what's on hand. REV, VEX, and the motor vendor publish a recommended breaker size for each motor. A NEO or Kraken on the drivetrain wants a 40 A breaker; a small mechanism motor may want 30 A so it trips before the motor or its wiring overheats. Oversizing "so it stops popping" just moves the failure from the breaker to the wire.

High-current: drive and mechanism motors

Nearly all your motor controllers land on high-current channels with a 40 A (or sometimes 30 A) auto-reset breaker. Auto-reset breakers are the norm because a momentary stall shouldn't end your match — the breaker trips, cools for a second or two, and re-closes. If you're seeing repeated trips, that's a signal to check current limiting in software, not to jump to a bigger breaker.

Low-current: roboRIO, radio, sensors

The roboRIO accepts a wide input voltage and draws modestly, so a low-current channel with a 10 A fuse is the standard. The radio must be fed regulated power — never raw battery voltage straight off a channel — so it goes through a Voltage Regulator Module (VRM) or a dedicated Radio Power Module, and that regulator's input lands on a low-current channel. Sensors, LED controllers, and other small boards fill out the remaining low-current and switchable channels.

ATO vs ATM: don't mix up the form factors

This trips up rookies every year. The high-current channels take ATO/ATC (full-size) fuses and breakers; the low-current and switchable channels take ATM/APM (mini) fuses. They are physically different sizes and not interchangeable. Order both, label your spares, and keep a few of each amperage in your pit kit — a blown fuse with no replacement is a match-ending problem you can prevent for a few dollars.

Wiring the PDH cleanly

A tidy PDH is a debuggable PDH. When something fails at competition, you want to trace a channel by eye in seconds, not unpick a bird's nest.

Battery input and the main breaker

The battery feeds the PDH through the 120 A main breaker. Run your heavy leads (typically 6 AWG) from the battery's Anderson SB connector to the main breaker, then from the main breaker into the PDH's main power terminals. The main breaker is the master cutoff for the whole robot — it must be reachable and it must be in the battery-positive path.

Wire gauge is not optional. The battery-to-PDH run carries the entire robot's current, so it uses heavy gauge (commonly 6 AWG). Per-channel wire is sized to the breaker: roughly 10 AWG for 40 A channels, 12–14 AWG for 30 A, and thin 18–22 AWG only on low-current channels. Undersized wire on a high-current channel is the classic hidden cause of brownouts and melted insulation.

Landing wires in the WAGO terminals

One of the PDH's nicest upgrades over older boards is toolless latching WAGO terminals. You lift the lever, insert a properly stripped and (ideally) ferruled wire, and close the lever — no screwdriver, no wago tool, no stripped screw heads. Strip to the length REV specifies, make sure no stray strands stick out to short against a neighbor, and give every wire a gentle tug test before you call it done.

Wire gauge per channel

Keep runs short, route power and signal separately where you can, and label both ends of every channel wire (channel number + device). Color discipline helps: keep red on positive and black on negative throughout, and don't let a channel's pair diverge in gauge. If you're standardizing your whole robot's harness, the how to wire an FRC robot guide covers gauge charts and routing in depth, and the guides hub links the rest of the electrical series.

Using the switchable channel

Channel 23's software on/off control is genuinely useful once you know what to do with it. The classic use is status LEDs and signal lights — you can cut or restore their power from robot code without wiring a physical relay or spare Spike. Because it's controlled over CAN, you toggle it from your robot program (the WPILib Power Distribution API exposes the switchable channel as a settable output), so you can, for example, light an indicator when a game piece is captured or when the robot is aligned.

Treat it like any other low-current channel for protection — 15 A rating, ATM/APM fuse — and don't try to switch a real motor on it. It's for indicators and light auxiliary loads, not drivetrain power.

CAN telemetry and current monitoring

The feature that makes the PDH more than a splitter is its CAN telemetry. The PDH sits on the robot's CAN bus and reports, in real time: the current on every one of the 24 channels (0–23), total robot current draw, and battery voltage — at higher resolution and refresh rate than the older PDP. It carries a 120 Ω CAN termination like other bus-end devices, and it also has a USB-C port so you can connect it to the REV Hardware Client to update firmware and diagnose faults directly.

Why you care: per-channel current is a debugging superpower. A motor that's binding shows up as an abnormally high current on its channel. A brownout becomes explainable when you can see battery voltage sag against total draw. Many teams log PDH data every match and review it afterward to catch a mechanism that's drawing more than it should before it becomes a failure. If CAN is new to you, the FRC CAN bus guide explains addressing, termination, and wiring order — the PDH is just one more device on that daisy chain.

Wire the PDH into your CAN chain, not off to the side. The PDH's telemetry only reaches the roboRIO if it's actually on the bus. A loose CAN connection means no current data and, worse, can silently break communication for devices downstream of it.

PDH vs PDP: what changed

Older robots (and plenty of veteran teams' spares) run the CTRE Power Distribution Panel (PDP). Both boards are legal and both do the same core job, but the PDH is the newer design with more channels and more diagnostics. Here's the honest comparison:

The practical takeaways: the PDH gives you more high-current channels (20 vs 8), a switchable channel, an at-a-glance voltage readout, and toolless terminals. The PDP is completely fine if you already have one and your channel count fits — it even reports temperature, which the PDH does not surface the same way. In WPILib the two are nearly interchangeable in code via the Power Distribution class; you just tell it which module type you have. The PDH slots into the broader REV ION ecosystem alongside the SPARK motor controllers and the Pneumatic Hub, which is a real reason teams standardize on it.

Common mistakes

A short list of the PDH mistakes that actually cost teams matches:

• Oversizing breakers to stop nuisance trips. If a channel keeps popping, the fix is current limiting in software or a mechanical check — not a bigger breaker that lets the wire overheat instead.
• Mixing ATO and ATM. Putting a mini fuse where a full-size one belongs (or vice versa) leaves a channel unprotected or won't seat at all. Know which channels take which.
• Feeding the radio raw battery voltage. The radio needs a regulator (VRM or Radio Power Module). Wiring it straight to a PDH channel can damage it.
• Undersized channel wire. A 40 A breaker on 18 AWG wire is not protected. Match wire gauge to the breaker, always.
• Leaving the PDH off the CAN chain. No CAN, no telemetry — and you lose the current data that makes debugging fast. It also breaks devices downstream on the bus.
• Loose WAGO landings. A wire that isn't fully latched works until vibration shakes it loose mid-match. Tug-test every terminal.
• No spare fuses/breakers in the pit. A blown ATM fuse with no replacement is an avoidable DNP. Stock both form factors in common amperages.

Frequently asked questions

How many channels does the FRC PDH have?

The REV Power Distribution Hub has 24 channels total (0–23): 20 high-current channels rated up to 40 A, 3 low-current channels rated 15 A continuous, and 1 switchable low-current channel also rated 15 A.

What fuses and breakers does the PDH use?

The high-current channels (0–19) take ATO/ATC-size fuses or auto-resetting circuit breakers up to 40 A. The low-current and switchable channels (20–23) take ATM/APM-size ("mini") fuses. The two form factors are not interchangeable.

What is the switchable channel on the PDH for?

Channel 23 can be turned on and off in robot code over CAN, so you can control power to LEDs, indicator lights, or small auxiliary loads without a physical relay. It's a low-current channel (15 A, ATM/APM fuse) and shouldn't be used to switch a motor.

What's the difference between the PDH and the PDP?

The REV PDH has 24 channels (20 at 40 A), a switchable channel, an LED voltage display, USB-C configuration, and toolless WAGO terminals. The older CTRE PDP has 16 channels (8 at 40 A, 8 at 30 A) and reports temperature but has no switchable channel or voltage display. Both are legal and both report per-channel current over CAN.

What breaker size should I use for a drive motor?

Drive motors like the NEO, Kraken, Falcon, or CIM typically use a 40 A auto-resetting breaker on a high-current channel. Always follow the motor vendor's recommended breaker size rather than guessing — oversizing shifts the failure point from the breaker to the wiring.

Can I read PDH current in my robot code?

Yes. The PDH publishes per-channel current, total current, and battery voltage over CAN. In WPILib you access it through the Power Distribution class, which works with both the PDH and PDP — you just specify the module type. Many teams log this data every match to catch mechanisms drawing more than they should.

The PDH rewards teams that treat wiring as a real subsystem: label every channel, size every breaker to its wire, keep it on the CAN bus, and glance at the voltage display before each match. Do that and the board mostly disappears into the background, which is exactly where you want your power distribution to live.