40 AWG Wire Gauge Chart

Property	Value
Gauge 40 Diameter (in)	0.00314 in
Gauge 40 Diameter (mm)	0.0799 mm
Gauge 40 Turns of Wire (per inch)	318.0 turns/in
Gauge 40 Turns of Wire (per cm)	125.0 turns/cm
Gauge 40 Cross-Sectional Area (kcmil)	0.00989 kcmil
Gauge 40 Cross-Sectional Area (mm²)	0.0 mm²
Copper Resistance (Ω/km or mΩ/m)	3441.0 mΩ/m
Copper Resistance (Ω/kft or mΩ/ft)	1049.0 mΩ/ft
NEC Copper Wire Ampacity (60°C)	0 A
NEC Copper Wire Ampacity (75°C)	0 A
NEC Copper Wire Ampacity (90°C)	0 A
Fusing Current (10 s)	1.0 A
Fusing Current (1 s)	1.5 A
Fusing Current (32 ms)	8.5 A

Frequently Asked Questions (FAQs) About 40 AWG Wire

What does AWG stand for?

AWG stands for American Wire Gauge, a standardized system for measuring wire sizes. The smaller the AWG number, the larger the wire diameter.

How does 40 AWG compare to 38 AWG?

40 AWG wire is smaller than 38 AWG, with a diameter of 0.0799 mm compared to 0.1 mm for 38 AWG. It has the same ampacity (0 A at 90°C) but a smaller cross-sectional area and higher resistance.

What applications are suitable for 40 AWG wire?

40 AWG wire is typically used for extremely low-current applications, such as fine electronics, hobby projects, or small signal wiring, due to its limited ampacity.

What happens if the fusing current is exceeded?

If the fusing current is exceeded (e.g., 1 A for 10 seconds in 40 AWG), the wire will overheat and melt, potentially causing a fire hazard or circuit failure.