Ampacity is the maximum current value a conductor can carry safely in certain working conditions without crossing the temperature safety limit. the unit of current is ampers, the use of accuate wire size for cirucit is important to avoid any damage overheating and fire chances. here we will make a wire ampacity chart that will help to find the accurate wire size for your projects based on wire materials and other parameters. let’s get started with the wire ampacity chart.
What is ampacity?
- The ampacity is a factor that is used for measuring the high current-carrying capacity of wire in amperes for certain loads.
- The current-carrying feature is related to electrical cables and is defined as the high current handled by the cable before it gets heated.
- The resistance factor of the wire causes heating and it is based on conductor size, insulation of conductor, and working condtions.
- The larger size conductor has low resistance for high current flow and losses will also be low for less resistance.
- If we increase the size of conductors the current carrying capacity will increase. The high-temperature resistance also provides a high ampacity of conductior.
- The 90-degree insulation rating will provide a high current carrying capacity as compared to 70-degree created insulation.
- The installation conditions and temperatures have an effect on heat dissipation from the cable and in a result wire ampacity or current carrying capacity.
- Cable installed in air or ground at low temperatures has higher ampacity than in high-temperature conditions.
- Some factors that affect the ampacity of wire are
-
- Device amperage.
- Ambient temperature.
- insulation materials.
- Conductor size.
- Bundling, Grouping, or enclosures.
Factors for Determine Wire Ampacity
Conductor/Wire Size:
- The larger wire gauge size will have high ampacity. Larger AWG wire sizes provide a high surface area for heat dissipation and have a larger cross-sectional area for current flow.
Conductor Materials:
- The material of the wire also affects current-carrying features. Normally copper and aluminum wires are used; copper has high ampacity as compared to aluminum.
Number of Conductors:
- Head dissipation is less for insulated conductors that are in bundle form.
Insulation Type:
- Insulation materials protect wire conductors since they carry current. Different insulations handle different values of heat and affect wire ampacity.
Conditions:
- The environmental conditions also have a high effect on wire ampacity. The technique used for wire installation and environmental temperature also has an effect on wire ampacity since cable in high temperature has low ampacity.
Wire Ampacity Chart
Wire ampacity chart for copper material wires
wire ampacity chart for Copper | |||
60°C (140°F) NM-B, UF-B |
75°C THW, USE, XHHW THWN, SE, |
90°C THWN-2,  USE-2 THHN, XHHW-2, |
Wire Gauge Size
|
15 | 20 | 25 | 14 |
20 | 25 | 30 | 12 |
30 | 35 | 40 | 10 |
40 | 50 | 55 | 8 |
55 | 65 | 75 | 6 |
70 | 85 | 95 | 4 |
85 | 100 | 115 | 3 |
95 | 115 | 130 | 2 |
— | 130 | 145 | 1 |
— | 150 | 170 | 1/0 |
— | 175 | 195 | 2/0 |
— | 200 | 225 | 3/0 |
— | 230 | 260 | 4/0 |
— | 255 | 290 | 250 |
— | 285 | 320 | 300 |
— | 310 | 350 | 350 |
— | 380 | 430 | 500 |
— | 420 | 475 | 600 |
— | 475 | 535 | 750 |
— | 545 | 615 | 1000 |
Wire ampacity chart for Aluminum Material wires
Aluminum Wire | ||
75°C (167°F) THW, THWN, SE, USE, XHHW |
90°C (194°F) XHHW-2, THHN, THWN-2 |
Wire Gauge Size |
20 | 25 | 12 |
30 | 35 | 10 |
40 | 45 | 8 |
50 | 55 | 6 |
65 | 75 | 4 |
75 | 85 | 3 |
90 | 100 | 2 |
100 | 115 | 1 |
120 | 135 | 1/0 |
135 | 150 | 2/0 |
155 | 175 | 3/0 |
180 | 205 | 4/0 |
205 | 230 | 250 |
230 | 260 | 300 |
250 | 280 | 350 |
310 | 350 | 500 |
340 | 385 | 600 |
385 | 435 | 750 |
445 | 500 | 1000 |
Ampacity chart for All Types of Single Conductor Insulation
80°C | 90°C | 105°C | 125°C | 150°C | 200°C | AWG |
AMPERES PER CONDUCTOR | ||||||
2 | 3 | 3 | 3 | 3 | 4 | 30 |
3 | 4 | 4 | 5 | 5 | 6 | 28 |
4 | 5 | 5 | 6 | 6 | 7 | 26 |
6 | 7 | 7 | 8 | 8 | 10 | 24 |
8 | 9 | 10 | 11 | 12 | 13 | 22 |
10 | 12 | 13 | 14 | 15 | 17 | 20 |
15 | 16 | 18 | 20 | 22 | 24 | 18 |
18 | 20 | 24 | 26 | 29 | 32 | 16 |
20 | 25 | 33 | 40 | 40 | 45 | 14 |
25 | 30 | 45 | 50 | 50 | 55 | 12 |
35 | 40 | 58 | 70 | 70 | 75 | 10 |
Correction Factors Different air Temperatures
80C | 90C | 105C | 125C | 150C | 200C |
Temperature (°C)
|
1 | 1 | 1 | 1 | 1 | 1 | 30 |
0.88 | 0.9 | 0.92 | 0.95 | 0.96 | 0.97 | 40 |
0.75 | 0.8 | 0.82 | 0.89 | 0.91 | 0.93 | 50 |
0.58 | 0.67 | 0.73 | 0.83 | 0.87 | 0.91 | 60 |
0.35 | 0.52 | 0.61 | 0.76 | 0.82 | 0.87 | 70 |
– | 0.3 | 0.46 | 0.69 | 0.76 | 0.84 | 80 |
– | – | 0.3 | 0.61 | 0.71 | 0.8 | 90 |
– | – | – | 0.51 | 0.65 | 0.77 | 100 |
– | – | – | – | 0.5 | 0.66 | 125 |
– | – | – | – | – | 0.54 | 150 |
Carrying Capacity Chart at 40C
AWG | 150C Tinned Copper | 200C Tinned Copper |
24 | 6.6 | 7.2 |
22 | 9 | 9.6 |
20 | 13 | 14 |
18 | 17 | 18 |
16 | 22 | 24 |
14 | 34 | 36 |
12 | 43 | 45 |
10 | 55 | 60 |
8 | 76 | 83 |
6 | 96 | 110 |
4 | 120 | 125 |
3 | 143 | 152 |
2 | 160 | 171 |
1 | 186 | 197 |
1/0 | 215 | 229 |
2/0 | 251 | 260 |
3/0 | 288 | 297 |
4/0 | 332 | 346 |
250 | 365 | 385 |
300 | 414 | 436 |
350 | 461 | 486 |
400 | 495 | 522 |
500 | 563 | 593 |
Current Carrying Conductor Adjustment Factors
Number of Conductors in Cable
|
Wire Ampacity Adjustment Factor
|
1-3 | 1 |
4-6 | 0.8 |
7-9 | 0.7 |
10-20 | 0.5 |
21-30 | 0.45 |
31-40 | 0.4 |
41 or more
|
0.35 |
How to calculate ampacity for wire?
- For measuring the wire ampacity, divide the wattage of the device by the rated voltage. This value provides the wire current ampacity if the temperature of the conductor increases 30 degrees.
use wire size calculator for finding wire size
How do you calculate amps to wire size?
- If you have an AC single phase, get the ampere value of the circuit, the one-way length of cable that is needed to connect, and the wire material resistivity. Take the product with these measured values and then obtain the result with 2…
- Now divide the find value with voltage losses.
How many amps are wires rated for?
Copper | Aluminum | |
12 | 20 | 20 |
10 | 30 | 30 |
8 | 40 | 40 |
6 | 55 | 50 |
Why is ampacity important?
- For electrical transmission and distribution lines, ampacity is the main factor for finding the current-carrying feature of wire. In a conductor, certain resistance exists for current flow that causes voltage losses and power dissipation in the heated conductor.
What factors affect ampacity?
- The conductor size is an important factor for an ampacity if a larger circular area wire has a high current-carrying capacity.
- High maximum temperature rating insulation also provides high current capacity.
- Ambient temperature is also important for affecting wire ampacity.
How to increase ampacity?
- Increasing the ampere in a circuit reduces the resistance that causes voltage losses.
What are the three types of wires?
- Live wire (L)
- Neutral wire (N)
- Earth wire (E)
What is the most commonly used wire size?
- There are different sizes for working with ampers of circuit. The larger number of amps wire will be small. The common gauge sizes used at residential workings are 14-gauge and 12-gauge.
What is an ampacity correction factor?
- The correction factor is multiplied with the ampacity rating for setting value according to certain conditions. That multiple is less than, equal to, or greater than one.
What are the features of wire?
- The main features of cable wires are conductivity, insulation resistance, and capacity. Conductivity defines features of material to carry current. Copper and aluminum are used in wires since they have high conductivity. Read our more Engineering Blogs
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