Wire Gauge Selection by Current (AWG)
Why gauge matters
Section titled “Why gauge matters”Wire has resistance. Push too much current through too thin a wire and it heats up, drops voltage, and can melt its insulation or start a fire. American Wire Gauge (AWG) is the standard sizing - counterintuitively, smaller AWG numbers mean thicker wire (6 AWG is much thicker than 18 AWG).
The FRC wire gauge table (Rule R622, Table 8-4)
Section titled “The FRC wire gauge table (Rule R622, Table 8-4)”The Game Manual ties minimum wire gauge directly to the branch circuit’s breaker/fuse rating:
| Circuit / current | Minimum wire gauge |
|---|---|
| Main power path (battery, 120A breaker, PD feed) | 6 AWG (R609) |
| 31-40A breaker-protected circuit | 12 AWG |
| 21-30A breaker-protected circuit | 14 AWG |
| 6-20A breaker / 11-20A fuse; PDH-to-PCM/PH; PD-to-roboRIO; PDH-to-VRM/RPM | 18 AWG |
| Motor power adapter board circuit; =5A breaker / =10A fuse | 22 AWG |
| VRM 2A circuits / =2A fuse | 24 AWG |
| roboRIO PWM outputs | 26 AWG |
| Signal-level circuits (=1A, incl. CAN) | 28 AWG |
These are minimums - you may always go thicker. Many teams use 12 AWG for all 40A motor branches for simplicity.
Concrete examples
Section titled “Concrete examples”- A Kraken X60 or Falcon 500 drive motor on a 40A breaker: 12 AWG to the motor controller.
- The roboRIO on a 10A channel: 18 AWG.
- The VH-109 radio 12V input: 18 AWG (R626 also requires 18 AWG or larger here).
- The CAN bus between devices: 28 AWG minimum (CAN is a signal-level circuit per Table 8-4); many teams use twisted-pair cable and heavier 22 AWG for durability, though neither is required by rule.
- The battery and main breaker leads : 6 AWG (some high-power drivetrains use heavier 4 AWG).
Note: wires originally attached to a legal device (e.g. the leads molded onto a SPARK MAX) are part of the device and exempt, provided they are fed by the smallest breaker/fuse that lets the device work.
Stranded, not solid
Section titled “Stranded, not solid”FRC robots vibrate and flex constantly, so always use high-strand-count stranded copper wire , never solid wire. Stranded wire survives vibration and routes more easily. High-strand 12 AWG is flexible enough to route around tight bends and connectors despite its thicker gauge.
Color coding (R624)
Section titled “Color coding (R624)”Non-signal wiring with constant polarity must follow polarity colors: red, yellow, white, brown, or black-with-stripe for positive; black or blue for negative. Consistent color coding makes debugging dramatically faster and is required for inspection.
Sources
Section titled “Sources”Key takeaways
Section titled “Key takeaways”- Smaller AWG = thicker wire; match gauge to the protecting breaker/fuse per Table 8-4 (R622).
- Use 6 AWG main path, 12 AWG for 31-40A, 14 AWG for 21-30A, 18 AWG for 6-20A (and the radio/roboRIO feeds), 22 AWG for signal/CAN.
- These are minimums - you may always go thicker; many teams default 40A branches to 12 AWG.
- Always use high-strand-count stranded copper and follow the R624 color code (red/positive, black/negative). Device-attached leads are exempt.
This lesson was adapted from learnfrc.com.