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Electrical Code for Wire Type and Size

How to Know What Wire Size and Type to use for Home Electrical Wiring – Continuing the circuit with the same wire size and type is essential to maintain the integrity of the circuit.

Electrical Wire Size
Electrical Question: Is it legal to start a circuit with AC 12-2 and then mid circuit change the cable type to NM 12-2?

This Electrical Wiring Question came from: Eric, a Homeowner from Fairfax, Virginia.

Dave’s Reply:
Thanks for your electrical wiring question Eric.

How to Select the Right Size and Type of Electrical Wire

Maintaining Circuit Integrity

Wire Type Definitions In This Discussion

Components of Maintaining Circuit Integrity include Items within the Circuit that have the same Circuit Rating Factors, such as:

The Dangers of Not Maintaining Electrical Circuit Integrity include:

The Following will assist you with your electrical question:

Circuit Wiring

Electrical Panel Circuit Listing

Electrical Wire for the Home

Electrical circuit
Electric Circuit Listing
The size of the home electrical service panel is designed by calculating the square footage of the home and factoring in the code requirements for the electrical circuits that are required.

For more information about Electrical Code
Electrical Code
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Wiring GFCI Outlets
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Wiring 3-Wire and 4-Wire Electric Range
Wiring 3-Wire and 4-Wire Dryer Cord and Dryer Outlet
How to Troubleshoot and Repair Electrical Wiring
Wiring Methods for Upgrading Electrical Wiring
NEC Codes for Home Electrical Wiring
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FAQs Frequently Asked Questions and Comments

2 Responses to “Electrical Code for Wire Type and Size”
  1. Brian says:

    I am adding a couple outlets to an older house, i believe the existing wire is 12-2 (larger diameter wire) can i extend from the existing outlet with a 14-2 wire? Both are romex.

    • Dave Rongey says:

      Hi Brian,
      When extending or replacing the wiring of an existing circuit it is important to maintain the same wire size or gauge of the same amperage rating. This will prevent confusion about the actual capacity of the circuit and will maintain the integrity of the original circuit. 14-2 is commonly a 15 amp circuit rating, and 12-2 is commonly a 20 amp rated circuit, so you can see that these wire sizes should not be installed within the same circuit.
      When upgrading electrical systems of an older home it is often necessary to install new circuits to areas such as the kitchen and bathrooms and provide GFCI circuit protection as well.


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