Conductor Size Calculator
Watts = 0
Kilowatts = 0
Amps = 0
Voltage = 120
Conductor Type = 1
Lowest Temp Rating = 1
Conductor Material = 1
Continuous Load = 1.25
Current-Carrying Conductors = 1
Ambient Temperature = 5
Minimum Conductor =
Step 1 =
Step 2 =
Step 3 =
Step 4 =
type_ambient = [[1.29;1.2;1.15]; [1.22;1.15;1.12]; [1.15;1.11;1.08]; [1.08;1.05;1.04]; [1;1;1]; [0.91;0.94;0.96]; [0.82;0.88;0.91]; [0.71;0.82;0.87]; [0.58;0.75;0.82]; [0.41;0.67;0.76]; [-1;0.58;0.71]; [-1;0.47;0.65]; [-1;0.33;0.58]; [-1;-1;0.5]; [-1;-1;0.41]; [-1;-1;0.29]]
Calculates the minimum conductor size required for circuits based on the temperature rating of the conductors and termination points and the load served. This template does not determine the maximum overcurrent protection allowed for conductors. See additional code commentary at the bottom of this overview.
Enter the load on the conductors in watts, kilowatts, or amps. Only enter a load in 1 section. The other 2 sections must be left blank.
- Voltage: Select the system voltage of the circuit.
- Conductor Type: Select the maximum operating temperature of the conductor used. See Table 1 for maximum operating temperatures for commonly used conductors.
- Lowest Temperature Rating: Choose the lowest temperature rating of any termination point on the circuit. Each device and conductor have a maximum operating temperature. This temperature rating will be marked on most devices and conductors. If the temperature rating is not marked on the device, section 110.14(C)(1) of the 2014 National Electrical Code requires us to default to 60° Celsius maximum operating temperature for circuits rated 100 amps or less or marked for 14 AWG through 1 AWG conductors and 75Ëš Celsius maximum operating temperature for circuits rated over 100 amps or marked for conductors larger than 1 AWG.
- Conductor Material: Select whether copper or aluminum conductors will be used.
- Continuous Load: Choose yes if the load is a continuous load and no if it is not. Continuous loads are defined as loads where the maximum current is expected to continue for 3 hours or more.
- #Current-Carrying Conductors: Choose the number of current-carrying conductors that will be installed in the raceway or cable. Ungrounded conductors (hots) are always considered to be current-carrying conductors. Grounding conductors are never considered to be current-carrying conductors (2014 NEC 310.15(B)(6)). Neutral conductors are considered to be current-carrying conductors in many applications but not always. See section 310.15(B)(5) of the 2014 National Electrical Code to determine when neutral conductors must be counted as current-carrying conductors.
- Ambient Temperature: Select the ambient temperature that the conductors will be installed in. If the ambient temperature is unknown, the calculator will default to 26° - 30° Celsius or 78° - 86° Fahrenheit. If the conductors will be installed in a circular raceway, exposed to sunlight on or above a rooftop, a temperature addition must be made to the ambient temperature.
- Minimum Conductor: This is the minimum conductor size required for circuits in this application.
Use Table 2 to find the temperature that must be added to the ambient temperature if these conditions exist.
Section 240.4(D) of the 2014 National Electrical Code limits the overcurrent protection for small conductors to 15 amps for 14 AWG copper, 20 amps for 12 AWG copper, 30 amps for 10 AWG copper, 15 amps for 12 AWG aluminum and 25 amps for 10 AWG aluminum.
Section 240.4(B) of the 2014 National Electrical Code allows the next higher standard overcurrent device, above the ampacity of the conductors, to be used provided the conductors are not supplying a branch circuit supplying more than one receptacle outlet, the ampacity of the conductors does not correspond to a standard ampere rating of an overcurrent device, and the next higher standard rating does not exceed 800 amps. (See 2014 NEC section 240.6 for a list of standard overcurrent device sizes)
Calculate the minimum size THWN copper conductor required for a noncontinuous 5,000 watt load that is connected to a single phase, 240 volt circuit, if 60° Celsius termination points are used. There will be 4 current-carrying conductors installed in the raceway with an ambient temperature of 88° Fahrenheit.
- Watts: 5,000
- Kilowatts: 0
- Amps: 0
- Voltage: 1∅, 240 volts
- Conductor Type: 75°C
- Lowest Temperature Rating: 60°C
- Conductor Material: Copper
- Continuous Load: No
- #Current-Carrying Conductors: 4-6
- Ambient Temperature: 31-35°C (87-95°F)
The minimum conductor for this application is 10 AWG.
Lowest Temp Rating