Home » FAQs » What Size Wire for 100 Amp Sub-Panel?

Table of Contents

  1. Introduction
  2. Wire Sizing Guidelines
  3. Conclusion


When it comes to installing a 100 amp sub-panel, one crucial consideration is choosing the appropriate wire size. The wire size determines the amount of electrical current it can safely carry without overheating or causing other hazards. In this article, we will discuss the guidelines for selecting the right wire size for a 100 amp sub-panel installation.

Wire Size

Wire Sizing Guidelines

1. Understand Ampacity Ratings

Ampacity refers to the maximum current that a wire can carry continuously without exceeding its temperature rating. It is essential to select a wire size with an ampacity rating suitable for a 100 amp sub-panel.

2. Consider Copper or Aluminum Wire

For residential installations, copper or aluminum wires are commonly used. Copper has higher conductivity and is less prone to corrosion, but it is more expensive than aluminum. Both materials have their advantages and considerations, so choose according to your specific needs and budget.

3. Consult Local Electrical Codes

Before proceeding with any electrical installation, it is crucial to consult the electrical codes and regulations in your area. Local codes may specify specific wire size requirements, installation methods, and safety guidelines that must be followed.

4. Determine Voltage Drop

Voltage drop refers to the decrease in voltage along the length of a wire run. To ensure efficient electrical distribution, it is important to consider voltage drop and select an appropriate wire size that minimizes this phenomenon. Various online calculators and charts are available to help determine voltage drop based on wire size, length, and load.

5. Selecting Wire Gauge

The American Wire Gauge (AWG) system is commonly used for measuring wire sizes. For a 100 amp sub-panel, the recommended wire size generally falls within the range of 3/0 AWG to 1/0 AWG for copper wires and 4/0 AWG to 2/0 AWG for aluminum wires. However, it is crucial to verify these specifications with local codes and consult a qualified electrician for precise recommendations.

6. Consider Wire Insulation Type

Wire insulation protects against moisture, abrasion, and other external factors. Different insulation types have varying temperature ratings and suitability for specific environments. Common insulation types include THHN, THWN, XHHW, and USE-2. Ensure that the chosen wire and its insulation type comply with local electrical codes.

7. Seek Professional Assistance

While this article provides general guidelines, it is always recommended to seek professional assistance for any electrical installations. A licensed electrician can assess the specific requirements of your sub-panel installation and ensure compliance with all relevant codes and regulations.


Choosing the right wire size for a 100 amp sub-panel is essential for the safe and efficient distribution of electrical power. Factors such as ampacity ratings, wire material, local electrical codes, voltage drop, and insulation type should all be considered during the selection process. By following these guidelines and consulting with a qualified electrician, you can ensure a successful and code-compliant installation of your 100 amp sub-panel.

Published On: 2023年6月29日Categories: ,