Current carrying capacity of copper conductors is a measure of the maximum current (in amperes) which a wire can safely carry without overheating, and destroying its insulation. The conductor heat is produced when an electrical current passes through it. The amount of heat dictates the amount of current that can be carried by the copper wire before the insulation or the conductor material starts to wear out.
Simply put, copper cable current carrying capacity is the safe amperage value of any wire depending on its size, the kind of the material it is made of, the type of insulation, and the environment it is used in. Theoretically, the current density of a bare copper wire can be raised to the point where it melts copper – however, in practice, reasons are given to ensure the failure of insulation and safety.
We shall discuss all the details of the current carrying capacity of copper cables in this guide which includes the size of cable gauge, temperature rating and installation location. You will also have ampacity charts and current carrying capacity copper cable ratings in square millimeters ( sq mm ) which will help you make a choice on the wire you use in your electrical projects.
Key Factors Affecting Current Carrying Capacity of Copper Conductors
Several factors decide the maximum current capacity of any conductor. The following list contains the most essential factors:
- Conductor Size: The ability of a conductor to transport current increases with its circular mil area dimension. The cables provide lower resistance and produce less heat.
- Insulation Temperature Rating: The maximum allowable temperature for insulation should not be exceeded by the conductor temperature due to current flow. Insulation will suffer damage when exposed to excessive heat along with safety risks during this time.
- Ambient Temperature: Higher ambient temperatures diminish the current capacity of conductors. The insulation’s limit can be reached with less additional heat which means the current capacity needs to be lower.
- Number of Conductors: When insulated conductors are bundled together the heat dissipation decreases. The current capacity diminishes wh en the number of conductors rises.
- Installation Conditions: The placement of conductors inside trays or conduits or ducts or raceways blocks air movement which reduces heat dissipation. Netting systems that utilize force-air cooling or ventilation provide relief against excessive heat.
The chart shows the current requirements to reach maximum temperature limits for different insulation types when operating a single insulated conductor in free air at 30°C ambient temperature. The current-carrying capacity of bundled conductors decreases because heat buildup becomes more pronounced. The derating table exists to modify the values because of these circumstances. The charts serve as reference material for general use in determining conductor and cable current ratings.
Amperes per Conductor in free air @ 30°C ambient temperature::
|
AWG Size |
Dielectric/Copper Temperature |
||||
|
@ 80°C |
@ 90°C |
@ 105°C |
@ 125°C |
@ 200°C |
|
|
30 |
2 |
3 |
3 |
3 |
4 |
|
28 |
3 |
4 |
4 |
5 |
6 |
|
26 |
4 |
5 |
5 |
6 |
7 |
|
24 |
6 |
7 |
7 |
8 |
10 |
|
22 |
8 |
9 |
10 |
11 |
13 |
|
20 |
10 |
12 |
13 |
14 |
17 |
|
18 |
15 |
17 |
18 |
20 |
24 |
|
16 |
29 |
22 |
24 |
26 |
32 |
|
14 |
27 |
30 |
33 |
40 |
45 |
|
12 |
36 |
40 |
45 |
50 |
55 |
|
10 |
47 |
55 |
58 |
70 |
75 |
Derating Factors for Bundled Conductors:
|
Bundle# |
Derating Factor (X Amps) |
|
2-5 |
0.8 |
|
6-15 |
0.7 |
|
16-30 |
0.5 |
Derating Factors for Bundled Conductors:
| Bundle# | Derating Factor (X Amps) |
| 2-5 | 0.8 |
| 6-15 | 0.7 |
| 16-30 | 0.5 |
Derating Factors for Bundled Conductors:
| Bundle# | Derating Factor (X Amps) |
| 2-5 | 0.8 |
| 6-15 | 0.7 |
| 16-30 | 0.5 |
Copper Cable Current Carrying Capacity Types
35 sq mm Copper Cable Current Carrying Capacity:
Commercial application uses 35 sq mm copper conductor cables because they offer outstanding current carrying capabilities. The copper conductors effectively distribute large electrical energy volumes through their efficient transmission system which upholds safety protocols. The cable’s strong capabilities enable users from homeowners to electricians and industries to choose them for dependable power distribution systems that meet different operational requirements.
10 sq mm Copper Cable Current Carrying Capacity:
The 10 sq mm cross-sectional area of this copper conductor cable provides strong current transmission capabilities, which makes it a top selection for electrical wiring applications. The residential wiring system incorporates these copper conductors for internal wiring applications while they serve medium-load requirements for dimmer switches. These wires successfully endure extended use in harsh conditions since they deliver resistance against heat corrosion and water damage.
6 sq m Copper Cable Current Carrying Capacity:
The electrical wiring sector selects copper conductor cables with a 6 sq mm cross-sectional area as their preferred option because of their superior conductivity and extended service life. The copper electrical conductor properties of this cable enable it to safely manage a maximum current of 67 amps while remaining more efficient than other materials. This cable has a high capacity that allows it to run a smaller number of cable runs hence making the cost of cable installation to be reduced. This copper conductor cable does not diminish under any circumstances and this is the reason why it is the best cable to be used in the residential and commercial power supply systems.
70 sq mm Copper Cable Current Carrying Capacity
The 70 sq mm copper conductor cable stands as an elite option for managing heavy electrical loads. This industrial-grade copper electrical conductor operates effectively in indoor & outdoor settings because it demonstrates exceptional heat resistance and mechanical durability. Large current transportation capabilities of this cable ensure dependable performance and secure connections, which makes it a trusted solution for demanding power distribution systems.
120 sq mm Copper Conductor Cable Current Carrying Capacity
The 120 sq mm copper conductor cable functions as a reliable and efficient wiring solution for residential and commercial applications. The copper electrical conductor maintains safe power transmission across long distances by providing 150 amps of regular current capacity and 175 amps of short circuit capacity. This cable proves to be the best option when high-current reliability and continuous operation are critical requirements
95 sq mm Copper Electrical Conductor Capacity
The 95 sq mm copper conductor features a design that enables safe operation of 240 amps at 240V throughout a single electrical run. The multi-stranded copper electrical conductor maintains flexibility and durability which makes it appropriate for low-voltage electrical systems. The conductor design provides strength that enables it to maintain performance while bending through corners.
16 sq mm 4 Core Copper Conductor Cable Capacity
Industrial facilities depend on the 4-core 16 sq mm copper conductor cable because it provides 95A current capacity. This cable type has protective outer shield combined with robust copper electrical conductors which maintain reliable performance throughout extreme temperature conditions and UV ray exposure.
95 sq mm Single Core Copper Conductor Cable Capacity
Single-core 95 sq mm copper conductor cables function within a current range of 40A to 300A based on installation conditions. The copper conductor cables work perfectly for commercial and residential installations where flexible power distribution with high strength is needed.
3 Core 6 sq mm Copper Conductor Cable Capacity
The key factor for secure wiring involves knowing the current carrying capacity of 3 core 6 sq mm copper electrical conductor cables. The power system requires these cables because they safeguard power systems from overloads together with reducing fire hazards while upholding building code regulations.
1 sq mm Copper Electrical Conductor Capacity
The 1 sq mm copper conductor cables deliver 30A capacity for residential and commercial buildings and warehouses. The wiring solution uses these cables because they provide long-lasting performance alongside excellent corrosion resistance and easy installation capabilities.
1.5 sq mm 3 Core Copper Conductor Cable Capacity
These cables operate at 20A per conductor when the temperature reaches 30°C and they have a regular use rating of 10A. The 1.5 sq mm 3-core copper conductor cable provides dependable power distribution for residential and basic commercial applications.
1.5 sq mm Copper Conductor Cable Current Capacity
The 1.5 sq mm copper electrical conductor functions as a lighting and general wiring component that can handle up to 25A of current. The cable offers affordability and quick installation while providing excellent conductivity which makes electricians choose it frequently.
185 sq mm Copper Electrical Conductor Cable Capacity
The 185 sq mm copper conductor provides 360 amps capacity while delivering high conductivity and tensile strength. The cables serve overhead wiring applications and heavy current load installations because of their suitable design.
2.5 sq mm 4 Core Copper Conductor Cable Capacity
The cables support current flow from 10A to 50A depending on their specific setup. The 2.5 sq mm 4-core copper conductor cable functions as an excellent power distribution tool because it provides dependable operation and safety when used according to system specifications.
2.5 sq mm Copper Electrical Conductor Capacity
The current capacity of 2.5 sq mm copper conductor cables reaches 24A. The copper electrical conductors serve versatile applications in domestic and industrial wiring systems due to their low resistance and low voltage drop characteristics.
240 sq mm Copper Conductor Cable Capacity
The 240 sq mm copper electrical conductor maintains a high capacity of 95 amps which makes it suitable for extensive installations. The cable finds extensive use in industrial motor systems and commercial power distribution networks to transmit power efficiently between distant locations.
25 sq mm 4 Core Copper Conductor Cable Capacity
The 25 sq mm 4-core copper conductor cable maintains stable power flow when installed in dry conditions at a 20A rating. The cable demonstrates strong resistance to environmental changes which allows its use in residential and commercial applications.
In conclusion, understanding about the current handling capabilities of copper cables remains crucial for establishing safe electrical systems. The cables exist in multiple dimensions with distinct capabilities for managing electrical currents. Your selection of appropriate copper cable according to application needs ensures both power reliability and safety compliance during transmission.
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Current Carrying Capacity of Copper Wire Per sq mm
| Nominal CrossSection (mm²) | 0,75 | 1,5 | 1 | 6 | 16 | 10 | 25 | 4 | 2,5 | 35 | |
|---|---|---|---|---|---|---|---|---|---|---|---|
| Group 1 | Protective Fuse(A) | 10 | 6 | 25 | 50 | 32 | 63 | 20 | 16 | 80 | |
| Current Carrying Capacity(A) Copper Wire | 15 | 11 | 33 | 61 | 45 | 83 | 25 | 20 | 103 | ||
| Group 3 | Protective Fuse(A) | 10 | 20 | 16 | 50 | 80 | 63 | 100 | 32 | 25 | 125 |
| Current Carrying Capacity(A) Copper Wire | 15 | 24 | 19 | 54 | 98 | 73 | 129 | 42 | 32 | 158 | |
| Group 2 | Protective Fuse(A) | 6 | 16 | 10 | 32 | 63 | 50 | 80 | 25 | 20 | 100 |
| Current Carrying Capacity(A) Copper Wire | 12 | 18 | 15 | 44 | 82 | 61 | 108 | 34 | 26 | 135 | |
| Nominal CrossSection (mm²) | 50 | 150 | 120 | 185 | 95 | 70 | 240 | 400 | 300 | 500 | |
| Group 1 | Protective Fuse(A) | 100 | 200 | 160 | 125 | ||||||
| Current Carrying Capacity(A) Copper Wire | 132 | 235 | 197 | 165 | |||||||
| Group 3 | Protective Fuse(A) | 160 | 315 | 315 | 400 | 250 | 200 | 400 | 630 | 500 | 630 |
| Current Carrying Capacity(A) Copper Wire | 198 | 391 | 344 | 448 | 292 | 245 | 528 | 726 | 608 | 830 | |
| Group 2 | Protective Fuse(A) | 125 | 250 | 250 | 315 | 200 | 160 | 315 | 400 | ||
| Current Carrying Capacity(A) Copper Wire | 168 | 335 | 292 | 382 | 250 | 207 | 453 | 504 | |||
Copper Wire Size & Amp Ratings
| Copper (Wire Size & Amp Ratings) | |||
|---|---|---|---|
| Wire Gauge Size | 60°C (140°F) NM-B, UF-B |
75°C (167°F) THW, THWN, SE, USE, XHHW |
90°C (194°F) THWN-2, THHN, XHHW-2, USE-2 |
| 14 | 15 | 20 | 25 |
| 12 | 20 | 25 | 30 |
| 10 | 30 | 35 | 40 |
| 8 | 40 | 50 | 55 |
| 1 | — | 130 | 145 |
| 1/0 | — | 150 | 170 |
| 2/0 | — | 175 | 195 |
| 3/0 | — | 200 | 225 |
| 6 | 55 | 65 | 75 |
| 4 | 70 | 85 | 95 |
| 3 | 85 | 100 | 115 |
| 2 | 95 | 115 | 130 |
| 4/0 | — | 230 | 260 |
| 250 | — | 255 | 290 |
| 300 | — | 285 | 320 |
| 750 | — | 475 | 535 |
| 1000 | — | 545 | 615 |
| 350 | — | 310 | 350 |
| 500 | — | 380 | 430 |
| 600 | — | 420 | 475 |
Temperature Rating of 2000 Volts Copper Conductor for 90, 75 and 60°C
| Size | Temperature Rating of Copper (Cu)Conductor | ||
|---|---|---|---|
| (AWG or kcmil) | 75°C (167°F) | 60°C (140°F) | 90°C (194°F) |
| 12 AWG* | 25 | 30 | |
| 1500 KCMIL | 625 | 525 | 705 |
| 2/0 AWG | 175 | 145 | 195 |
| 1750 KCMIL | 650 | 545 | 735 |
| 18 AWG | — | — | 14 |
| 700 KCMIL | 460 | 385 | 520 |
| 4 AWG | 85 | 70 | 95 |
| 800 KCMIL | 490 | 410 | 555 |
| 10 AWG* | 35 | 30 | 40 |
| 16 AWG | — | — | 18 |
| 750 KCMIL | 475 | 400 | 535 |
| 3 AWG | 100 | 85 | 115 |
| 900 KCMIL | 520 | 435 | 585 |
| 2 AWG | 115 | 95 | 130 |
| 1000 KCMIL | 545 | 455 | 615 |
| 1250 KCMIL | 590 | 495 | 665 |
| 8 AWG | 50 | 40 | 55 |
| 350 KCMIL | 310 | 260 | 350 |
| 600 KCMIL | 420 | 350 | 475 |
| 6 AWG | 65 | 55 | 75 |
| 400 KCMIL | 335 | 280 | 380 |
| 4/0 AWG | 230 | 195 | 260 |
| 300 KCMIL | 285 | 240 | 320 |
| 3/0 AWG | 200 | 165 | 225 |
| 500 KCMIL | 380 | 320 | 430 |
| 1/0 AWG | 150 | 125 | 170 |
| 250 KCMIL | 255 | 215 | 290 |
| 14 AWG* | 20 | 25 | |
| 1 AWG | 130 | 110 | 145 |
| 2000 KCMIL | 665 | 555 | 750 |
Single Insulated Copper Conductors Current Carrying Capacity
| Size | Temperature Rating of Copper Conductor | ||
|---|---|---|---|
| (AWG or kcmil) | 90°C (194°F) | 60°C (140°F) | 75°C (167°F) |
| 10 AWG* | 55 | 50 | |
| 600 KCMIL | 780 | 575 | 690 |
| 4 AWG | 140 | 105 | 125 |
| 500 KCMIL | 700 | 515 | 620 |
| 3/0 AWG | 350 | 260 | 310 |
| 8 AWG | 80 | 60 | 70 |
| 700 KCMIL | 850 | 630 | 755 |
| 2 AWG | 190 | 140 | 170 |
| 400 KCMIL | 615 | 455 | 545 |
| 800 KCMIL | 920 | 680 | 815 |
| 6 AWG | 105 | 80 | 95 |
| 250 KCMIL | 455 | 340 | 405 |
| 1/0 AWG | 260 | 195 | 230 |
| 3 AWG | 165 | 120 | 145 |
| 900 KCMIL | 980 | 730 | 870 |
| 1 AWG | 220 | 165 | 195 |
| 300 KCMIL | 500 | 375 | 445 |
| 2/0 AWG | 300 | 225 | 265 |
| 350 KCMIL | 570 | 420 | 505 |
| 4/0 AWG | 405 | 300 | 360 |
| 750 KCMIL | 885 | 655 | 785 |
| 1000 KCMIL | 1055 | 780 | 935 |
| 1250 KCMIL | 1200 | 890 | 1065 |
| 1500 KCMIL | 1325 | 980 | 1175 |
| 1750 KCMIL | 1445 | 1070 | 1280 |
| 2000 KCMIL | 1560 | 1155 | 1385 |
Copper Cable Density
|
Condition |
Standard Conditions |
High-Temperature Applications |
|
Current Density |
1 to 1.5 A/mm² |
Up to 2 A/mm² or more |
|
Description |
Typical range for general applications. |
Can be higher depending on cooling and insulation |
Copper Conductor Resistance Table
| Nom cross section | 0,05 | 0,14 | 0,126 | 0,08 | 0,34 | 0,22 | 0,5 | 6,0 | 1,0 | 16,0 | 10,0 | 1,5 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Cu conductor-tinned wires (Ohm/km) | ~380 | ~134 | ~150 | 237 | 39,0 | 99 | 26,0 | 3,30 | 19,5 | 1,21 | 1,91 | 12,2 |
| Copper conductor-plain wires (Ohm/km) | – | – | – | – | 36,0 | 96 | 24,5 | 3,08 | 18,1 | 1,15 | 1,83 | 12,1 |
| Welding cable (Ohm/km) | ~392 | ~138 | ~175 | ~244 | 40,1 | 76 | 26,7 | 3,11 | 20,0 | 1,24 | 1,95 | 13,7 |
| Cu conductor (tinned wires) | – | – | – | – | – | – | – | – | – | 1,19 | – | – |
| Copper conductor (plain wires) | – | – | – | – | – | – | – | – | – | 1,16 | – | – |
| Nom cross section | 2,5 | 25,0 | 4,0 | 35,0 | 70,0 | 50,0 | 120,0 | 300,0 | 150,0 | 500,0 | 400,0 | 630,0 |
| Cu conductor-tinned wires (Ohm/km) | 7,98 | 0,386 | 4,95 | 0,272 | 0,161 | 0,206 | 0,129 | 0,0641 | 0,0801 | 0,0396 | 0,0486 | 0,0286 |
| Copper conductor-plain wires (Ohm/km) | 7,41 | 0,387 | 4,61 | 0,268 | 0,153 | 0,193 | 0,124 | 0,0601 | 0,0754 | 0,0366 | 0,0470 | 0,0283 |
| Welding cable (Ohm/km) | 8,21 | 0,393 | 5,09 | 0,277 | 0,164 | 0,195 | 0,126 | 0,0607 | 0,0762 | – | 0,0475 | 0,0292 |
| Cu conductor (tinned wires) | – | 0,390 | – | 0,276 | 0,159 | 0,204 | 0,105 | – | – | – | – | – |
| Copper conductor (plain wires) | – | 0,379 | – | 0,268 | 0,155 | – | 0,125 | 0,0654 | 0,0817 | – | – | – |
Copper Wire Current Carrying Capacity Formula
The current carrying capacity of a copper wire can be calculated using the formula:
I = k × Aᵇ
Where:
- I = Current carrying capacity (in amperes, A)
- A = Cross-sectional area of the wire (in mm²)
- k and b = Constants based on factors such as insulation type and ambient temperature
Typical values:k = 2.5 and b = 0.5
Frequently Asked Questions About Copper Conductor
How to calculate the current rating of copper wire?
The current rating of copper wire depends on three main factors: the cross-sectional area of the conductor, the insulation material, its thickness & the surrounding environmental temperature conditions during installation. The standard calculation for current rating includes this formula:
Current (Amps) ≈ Area (sqmm) × Current density (A/sqmm)
Why is copper a conductor?
The low electrical resistance of copper enables quick electron flow because it functions as an excellent conductor. Copper serves as an excellent choice for electrical wiring due to its high conducting properties , corrosion-resistance and ductility alongside its high temperature endurance.
What is the conductivity of copper cable?
Copper exhibits an electrical conductivity value of 5.8 × 10⁷ S/m (Siemens per meter) at 20°C. Copper serves as the fundamental standard for conductivity measurements and industry professionals rate it at 100% IACS (International Annealed Copper Standard).
How much current can a 240 sqmm copper cable carry?
A 240 square millimeter copper cable has the capacity to transport between 415–500 Amps when placed in conduit and up to 600 Amps when exposed to open air. The actual carrying capacity of a 240 sqmm copper cable depends on installation method and insulation type and ambient temperature.
What is copper cable used for?
Copper cable is used in:
-Power generation and distribution
-Electrical wiring in homes and industries
-Electronics and telecommunication systems
-Electric vehicles and renewable energy systems




