Wire Ampacity Calculator implementation

Binding contract

This record describes what an executable surface must bind and validate. It does not claim that a public calculator, package, or production route is deployed.

Record owner

Guth Instruments

Lifecycle

verified-clean

Evidence ID

t7-068

Effect

Computation or source lookup only

Input and validation requirements

An ambient temperature such as 200 C lies outside the NEC correction-factor table and has no defined derating result. The calculator must reject it; extrapolating a factor or returning a numeric ampacity would be a hazard. The convention probe also shows that the conductor-count field needs an explicit current-carrying-versus-total definition.

Required corrections

No binding erratum is attached to this unique-name record. Implementers must still preserve the declared units, domain, and failure behavior.

Inspectable interface fixture

The sample below is evidence for interface and validation tests, not a production implementation.

{
  "inputs": {
    "material": "copper",
    "size": "12 AWG",
    "insulation": "THHN",
    "ambient_C": 30,
    "current_carrying_conductors": 3,
    "terminal_rating_C": 75
  },
  "expected_outputs": {
    "base_ampacity_90C_A": 30,
    "adjusted_ampacity_90C_A": 30,
    "terminal_limited_ampacity_A": 25,
    "code_max_allowable_ampacity_A": 20
  },
  "reference_data": {
    "table_310_16_copper_12_AWG": {
      "60C_A": 20,
      "75C_A": 25,
      "90C_A": 30,
      "source_convention": "NEC 2020 Table 310.16"
    },
    "ambient_correction_90C_at_30C": {
      "factor": 1,
      "source_convention": "NEC 2020 Table 310.15(B)(1)"
    },
    "current_carrying_adjustment_for_3": {
      "factor": 1,
      "source_convention": "NEC 2020 Table 310.15(B)(3)(a)"
    },
    "small_conductor_limit_12_AWG": {
      "maximum_A": 20,
      "source_convention": "NEC 2020 240.4(D)"
    }
  },
  "working": "Base 90 °C ampacity = 30 A. Ambient factor at 30 °C = 1.00. Three current-carrying conductors require no adjustment, factor = 1.00. Adjusted ampacity = 30 × 1.00 × 1.00 = 30 A. The 75 °C terminal limit is 25 A, so terminal-limited ampacity = min(30, 25) = 25 A. NEC 240.4(D) limits 12 AWG copper to 20 A, so final code maximum = min(25, 20) = 20 A."
}

Other records

Sources and evidence

These pointers bind the page to evidence. They do not grant authority or collapse verification into deployment.

• VERIFIED_LEDGER.json
• evidence-tranche7/tranche7-results.json