Wire Gauge Guide
Edit on GitHubChoosing wire sizes for the beacon: the current table, the voltage-drop math, and the gauges the build actually uses.
Wire Gauge Guide
Wire gauge decides three things: how much current the wire can carry, how much voltage it drops, and how well it survives flexing. The beacon uses three gauges for three jobs.
The current table (AWG)
| AWG | Max current (chassis wiring) | Typical use |
|---|---|---|
| 30 | 0.5 A | Signal wires |
| 28 | 0.8 A | Signal, GPS UART |
| 26 | 1.5 A | Buttons, LED |
| 24 | 2.5 A | Power rails |
| 22 | 4 A | Battery and charger paths |
| 20 | 6 A | Cell leads (overkill, but flexible) |
The beacon’s three gauges
| Path | Gauge | Why |
|---|---|---|
| Signal (UART, I2C, buttons) | 26 - 28 AWG | Small, flexible |
| Power rails (3.3 V) | 24 AWG | 120 mA bursts with margin |
| Cell and charger | 22 AWG | 1 A charging, low drop |
The voltage-drop math
Drop = I x R. Ten cm of 26 AWG at 120 mA drops about 4 mV: nothing. Ten cm of 30 AWG at 1 A (charging) drops about 30 mV: still fine. The drop only matters on the cell path under the TX burst, where the Brownout Protection page explains the consequences.
The flex rule
Thin wire breaks with flexing, thick wire is stiff. In a case that opens and closes, use stranded wire and strain relief at every connector (see Wiring Order and Routing). A broken wire inside a case is the most common intermittent fault in the project.
The colour convention
The project uses a fixed colour scheme: red for the cell positive, black for ground, orange for 3.3 V, and any other colour for signals. Consistency is worth more than any single wire choice.
Related pages
- Connector Types for the connectors
- Wire and Connectors for the wiring guide
- Wiring Order and Routing for the layout