Calculating the proper wire size can prevent you from wasting money on unnecessary big cables, so we've created this 24V wire size calculator to get the optimal size.
As a calculation example, we'll see what wire size for a 24V trolling motor is needed.
You can also look at the FAQ list for other common electrical problems, like the wire size needed for a 20 amp 220-volt circuit.
Formula to calculate the wire size for a 24V system.
The equation varies depending on the type of electrical system used.
DC/ single-phase systems
To calculate a 24 V wire size in a direct current (DC) or an alternating current (AC) single-phase system, use this formula:
where:
- — Voltage drop between the source and the farthest end of the wire, measured in volts;
- — Electric current through the wire, in amperes;
- — Resistivity of the conductor material, in Ω⋅m;
- — Length of the wire (one-way), in meters;
- — Cross-sectional area of the wire, in square meters; and
The 2 coefficient before L accounts for the return path after the current passes the load.
Three-phase systems
For a three-phase AC system, three cables are used instead of one. The calculator accepts the total line voltage and current of the combined three wires.
The equation for a single wire is modified with a √3 factor, which is needed to convert between the system's phase current and line current. For each of the three cables, the area is given by:
The factor of 2 disappears, as three-phase systems don't possess a return cable.
🙋 Important:
- The result given by the three-phase formula accounts for the area of only one wire. Therefore, you'll need three wires of that size to build your three-phase cable.
- This 24V wire size calculator has the three-phase system option enabled, but, for most applications, 24 V systems will work in DC or AC single-phase.
- For source voltages of more than 50 V, if L<16 m, this calculator assumes a distance of 16 m so that the wire doesn't result in excessively tiny sizes for small lengths.
- V is the voltage drop, not the source voltage magnitude.
- ϱ varies with temperature.
Example: What wire size for a 24V trolling motor is needed
Suppose you're choosing the wire size of a trolling motor operating at 48 amps. The one-way distance (from source to load) is 25 ft, and the maximum operating temperature is 50°C. What is the required size for this operation?
Use our 24V wire size calculator following these steps to know the answer:
- As trolling motors and 24 V systems operate in DC, choose "DC/AC Single-phase" as the electrical system.
- As recommended in most applications, choose a 3% allowable voltage drop.
- Copper is the most common wire material. Therefore, you can choose it as your conductor material.
- Type 56 A in the "Current (I)" box.
- Type 25 ft in the "One-way distance" box.
- Type 50°C in the "Maximum wire temperature" box.
That's it. The required wire size should be 97.95 mm² or 0000 (4/0) AWG.
Other interesting wire size tools
We've also created other tools to ease your life and solve similar problems:
Disclaimer
These results are solely for educational purposes. Before beginning any electrical project, always get the advice of an experienced electrician.
FAQs
What wire size for a 20 amp 220-volt circuit should I use?
The wire size for 20 amp 220-volt circuits is 10 AWG for cable lengths below 40 m. This answer assumes using a copper cable at a maximum operating temperature of 100°C and an allowable 3% voltage drop. For longer wires, use our wire size calculator.
What wire size for a 24V trolling motor should I use?
Usually, a 4 AWG will be more than enough for 24 V trolling motors. Even so, to calculate the optimum wire size, follow these steps:
- Determine the trolling motor electric current (in amps), cable length L (in meters), conductor resistivity ϱ (in Ω⋅m), and allowable voltage drop V (usually 3% of the source voltage).
- Input the values in this formula:
A = (2IϱL) / V - Now you know the wire size for your 24V trolling motor!!! The formula provides the wire area in m². Multiply it by 1,000,000 to convert it to square millimeters.