Wire size calculator
wire_sizeRead-onlyIdempotent
Minimum conductor size for a circuit: NEC Table 310.16 ampacity at the termination temperature rating, the 240.4(D) small-conductor limits, voltage drop over the run, and the Table 250.122 equipment grounding conductor, increased in proportion under 250.122(B) when voltage drop upsizes the conductors.
Input Schema
TableJSON Schema
| Name | Required | Description | Default |
|---|---|---|---|
| amps | Yes | Breaker / load (A). | |
| feet | Yes | One-way distance (ft). | |
| temp | Yes | Termination rating. "60" = 60°C (NM-B, UF); "75" = 75°C (THHN in conduit); "90" = 90°C. | 75 |
| limit | Yes | Max voltage drop (%). | |
| phase | Yes | Phase. "1" = Single-phase; "3" = Three-phase. | 1 |
| volts | Yes | Voltage. "120" = 120 V; "208" = 208 V; "240" = 240 V; "277" = 277 V; "480" = 480 V. | 240 |
| material | Yes | Conductor. "cu" = Copper; "al" = Aluminum. | cu |
Output Schema
TableJSON Schema
| Name | Required | Description | Default |
|---|---|---|---|
| ok | Yes | ||
| url | Yes | ||
| code | Yes | ||
| rows | Yes | ||
| table | No | ||
| inputs | Yes | ||
| summary | Yes |