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Installing a sub panel is a smart way to expand your electrical system safely. Whether you are adding a garage workshop, outdoor shed, or basement upgrade, one of the most critical parts of the setup is selecting the right wire size. That is where a Sub Panel Wire Size Calculator comes in handy. It helps you choose the correct wire gauge based on load, distance, and voltage drop. Sub Panel Wire Size Calculator – Accurate Wire Gauge & Load Sizing Tool What is a Sub Panel Wire Size Calculator Why You Need a Sub Panel Wire Size Calculator How a Sub Panel Wire Size Calculator Works Factors That Affect Sub Panel Wire Size How to Use a Sub Panel Wire Size Calculator Example Calculations Using the Sub Panel Wire Size Calculator Copper vs Aluminum for Sub Panel Wiring NEC Guidelines for Sub Panel Wire Sizing Benefits of Using the Sub Panel Wire Size Calculator Conclusion

Choosing the wrong wire size can cause overheating, voltage loss, and even electrical fires. Using a reliable calculator ensures that your sub panel performs efficiently and complies with electrical standards.

What is a Sub Panel Wire Size Calculator

A Sub Panel Wire Size Calculator is an online tool designed to determine the appropriate wire gauge for your sub panel connection. It calculates based on three key inputs—load in amps, distance from the main panel, and voltage.

These factors directly affect how much current your wire can handle safely without causing overheating or excessive voltage drop. The calculator eliminates guesswork and makes sure your wiring meets NEC (National Electrical Code) requirements.

The main goal of a sub panel wire size calculator is safety and efficiency. Oversized wires increase cost unnecessarily, while undersized wires create hazards. By entering accurate values in the calculator, you can find the perfect balance between safety, performance, and cost.

Sub Panel Wire Size Calculator

Sub Panel Wire Size Calculator

Determine the correct wire gauge for subpanel installations based on load, distance, and voltage drop.

Subpanel Load (A): Voltage (V): 120V 240V 208V 480V Distance to Subpanel (m): Phase Type ▼: Single-phase Three-phase Wire Material ▼: Copper Aluminium Insulation Type ▼: THHN XHHW UF NM Voltage Drop Limit (%): Ambient Temperature (°C): Conduit Fill (%): Calculate

Why You Need a Sub Panel Wire Size Calculator

If you are planning to add a 60-amp, 100-amp, or 125-amp sub panel, you must know what wire size to use. Voltage drop and distance play a huge role in wire sizing. A wire that works perfectly for a 20-foot run might fail at 100 feet due to excessive voltage loss. The calculator helps prevent these issues by factoring in the run length and amperage demand.

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A sub panel wire size calculator also helps you plan your electrical budget accurately. Knowing the exact wire gauge before installation saves money and ensures you buy the correct type—copper or aluminum. Additionally, using the correct wire size improves the performance of tools, lights, and equipment connected to the sub panel.

How a Sub Panel Wire Size Calculator Works

A Sub Panel Wire Size Calculator uses mathematical formulas and standard NEC wire tables to determine the proper gauge. When you enter the current load (in amps), voltage (120V or 240V), distance (in feet), and acceptable voltage drop (usually 3% or less), the calculator computes the minimum wire size that can handle the load safely.

The calculator compares your inputs with known wire properties like resistance, ampacity, and voltage loss. It then outputs a recommended wire gauge, such as 6 AWG copper or 4 AWG aluminum.

Here is a simplified example of how wire sizing works:

Sub Panel Load (Amps)Distance (Feet)VoltageRecommended Copper Wire SizeRecommended Aluminum Wire Size60 Amps50 ft240V6 AWG4 AWG100 Amps75 ft240V3 AWG1 AWG125 Amps100 ft240V1 AWG2/0 AWG150 Amps125 ft240V1/0 AWG3/0 AWG200 Amps150 ft240V2/0 AWG4/0 AWG

This table shows how wire size increases with distance and amperage. The calculator performs this evaluation instantly, giving you a precise recommendation for your setup.

Factors That Affect Sub Panel Wire Size

Several factors influence the correct wire size, and a good Sub Panel Wire Size Calculator accounts for all of them:

1. Load in Amps: The more amps your sub panel draws, the thicker the wire needs to be. A 100-amp sub panel will always require larger wire than a 60-amp one.

2. Distance from Main Panel: As the distance increases, resistance also rises. To overcome this, you need a larger wire to keep voltage drop within safe limits.