What wire gauge handles 20A circuit?

NEC: AWG 12 copper minimum for 20A 120/240V branch circuit. AWG 10 for 30A, AWG 8 for 40A, AWG 6 for 55A. Always use next larger gauge if circuit length causes voltage drop > 3%.

How do I derate wire ampacity for high temperature?

NEC Table 310.15(B)(2)(a): multiply by 0.91 at 30°C ambient, 0.82 at 35°C, 0.71 at 40°C, 0.58 at 45°C, 0.41 at 50°C. Use 90°C insulation rating where available to reduce derating penalty.

What is conduit fill derating?

When 4+ conductors in conduit carrying load: derate to 80%. NEC 310.15(C): 4-6 conductors 80%, 7-9 conductors 70%, 10-20 conductors 50%, 21+ conductors 45% of Table 310.15(B) values.

Wire Gauge Ampacity Calculator

Find NEC ampacity for AWG and metric wire sizes. AWG 12 copper = 20A, AWG 10 = 30A, AWG 6 = 55A, AWG 2/0 = 135A. Ampacity derating for conduit fill, high ambient temperature, and continuous loads.

2D stress state at a point. All stresses in MPa.

σx — Normal Stress X (MPa)

σy — Normal Stress Y (MPa)

τxy — Shear Stress (MPa)

⚙ Mechanical Note: Results are based on standard textbook formulas and ISO/AASHTO references. Always verify critical designs with applicable codes (ISO 898, AASHTO 1993, AISC, Eurocode 3) and a qualified engineer.

How to Use

Enter the values for the patient or scenario you are assessing. Find NEC ampacity for AWG and metric wire sizes. AWG 12 copper = 20A, AWG 10 = 30A, AWG 6 = 55A, AWG 2/0 = 135A. Ampacity derating for conduit fill, high ambient temperature, and continuous loads. Use the wire ampacity result to inform your clinical assessment.

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Frequently Asked Questions

What wire gauge handles 20A circuit?

How do I derate wire ampacity for high temperature?

What is conduit fill derating?