Wire Ampacity Calculator
Calculate the current-carrying capacity of electrical wires based on AWG size, temperature, and installation conditions
About this calculator
The Wire Ampacity Calculator determines the safe current-carrying capacity of electrical wires based on American Wire Gauge (AWG) size, ambient temperature, and installation conditions. This tool is essential for electricians, engineers, and DIY enthusiasts to ensure proper wire sizing for electrical circuits. Using the correct ampacity prevents overheating, fire hazards, and electrical failures while maintaining code compliance and system safety.
How to use
Select your wire's AWG size from the dropdown menu, enter the ambient temperature where the wire will be installed, and choose the installation conditions (such as conduit type or free air). The calculator will instantly display the maximum safe amperage rating for your specific wire configuration.
Frequently asked questions
What is wire ampacity and why does it matter?
Ampacity is the maximum current a wire can safely carry without overheating. Exceeding this limit causes insulation damage, fire hazards, and electrical failures.
How does temperature affect wire ampacity?
Higher ambient temperatures reduce wire ampacity because the wire generates additional heat. Most ratings assume 30°C (86°F) ambient temperature with derating factors applied above this.
What installation conditions affect ampacity ratings?
Conduit fill, bundling with other wires, insulation type, and ventilation all impact ampacity. Wires in free air carry more current than bundled wires in conduit.