The answer? American Wire Gauge Conductor Size Table. The wire size chart below shows ⦠4 AWG 125 135 145 170 180 2 AWG 170 180 200 225 240 Current carrying capacity is defined as the amperage a conductor can carry before melting either the conductor or the insulation. For reference, the National Electrical Code (NEC) notes the following ampacity for copper wire at 30 Celsius: We assume that: load_current = fuse_size/1.25 (it is generally accepted that a fuse must be at minimum 125% the size of the load current); Using load_current and length, we compute the wire gauge that meets the chosen voltage drop. The number of devices connected to the circuit usually determines how much current will flow through the wire. ; We find a wire gauge for which the ampacity is higher than the fuse size. The smallest AWG size is 40 and the largest is 0000 (4/0). The larger the AWG number or wire guage, the smaller the physical size of the wire. Allowable ampacities of insulated copper conductors rated up to and including 2000 Volts, 60°C through 90°C (140°F through 194°F), Not more than three current-carrying conductors in raceway, cable, or earth (directly buried), based on ambient temperature of 30°C (86°F). Current Load Ratings - Copper (amps) 1) Multicore; 24: 0.51: 1.0: 22: 0.64: 1.5: 20: 0.81: 2.5 Current Limits AWG gauge Diameter Inches Diameter mm Ohms per 1000 ft Ohms per km Maximum amps for chassis wiring Maximum amps for power transmission OOOO 0.46 11.684 0.049 0.16072 380 302 OOO 0.4096 10.40384 0.0618 0.202704 328 239 OO 0.3648 9.26592 0.0779 0.255512 283 190 0 0.3249 8.25246 0.0983 0.322424 245 150 It is important to pick the correct size of wire so that the wire doesn't overheat. Check your local electrical code for the correct current capacity (ampacity) for mains and in ⦠American wire gauge (AWG) is a standardized wire gauge system for the diameters of round, solid, nonferrous, electrically conducting wire. Electrical current is measured in amps. Electrical - Electrical units, amps and electrical wiring, wire gauge and AWG, electrical formulas and motors. Wire Size: 60°C (140°F) 75°C (167°F) AWG (mm²) Copper: Aluminum: Copper: Aluminum: The tables below are intended to be a general guide for wire size and amp ratings. 12 AWG â maximum of 25 Amps in free air, maximum of 20 Amps as part of a 3 conductor cable; 10 AWG â maximum of 40 Amps in free air, maximum of 30 Amps as part of a 3 conductor cable. AWG Diameter (mm) Typical Max. Each wire size, or wire gauge (AWG), has a maximum current limit that a wire can handle before damage occurs. Sponsored Links. 2 amps. Theoretically, the amount of current Current (ampacity) Notes: The current ratings shown in the table are for power transmission and have been determined using the rule of 1 amp per 700 circular mils, which is a very conservative rating. Unless specifically permitted in Section 240.4(E) through (G), the overcurrent protection shall not exceed 15 amperes for 14 AWG, 20 amperes for 12 AWG, and 30 amperes for 10 AWG copper; or 15 amperes for 12 AWG and 25 amoeres for 10 AWG aluminum after any correction. Thatâs just 13% of their stated rating. Letâs stay with this example and see what maximum current the 14 AWG cable can handle over a 20 metre cable run. Conductor Size (AWG) Maximum Current Carrying Capacity Length 6 â 50 feet Length 51 â 100 feet 2 Wire 3 Wire 2 Wire 3 Wire #18 10 7 7 5.6 #16 13 10 10 7 #14 18 15 15 10 #12 25 20 20 15 #10 30 25 25 20 #8 40 35 35 25 ⦠The maximum current in a gauge #10 (5.26 mm2) cable with length 15 m is approximately 5 amps. (AWG or kcmil) Heat, caused by an electrical current flowing through the conductor, will determine the amount of current a wire will handle. Weâll use the same values we started with above, then reduce the current until the cable cross-sectional area is below 2.1 sq. mm (or 14 AWG). Temperature Rating of Copper Conductor. Size. ; We compare 2. and 3. above and keep the wire with the largest gauge.