National Electrical Code (NEC) Requirements

The NEC does not explicitly require twisting solid wires together before installing wire nuts. However, it does state that "Connections shall be made only with approved materials and methods."

Industry Best Practices

In the electrical industry, it is generally considered best practice to twist solid wires together before installing wire nuts for the following reasons:

Improved Electrical Connection

Twisting the wires creates a mechanically stronger connection between them, which reduces the risk of arcing or loose connections.

Better Grip for Wire Nuts

Twisted wires are easier for wire nuts to grip, preventing them from becoming loose or falling off.

Reduced Oxidation

Twisting the wires exposes fresh metal surfaces, which helps to reduce oxidation and improve electrical conductivity.

Easier Inspection

If the wire nuts are ever removed, twisted wires make it easier to reconnect them securely.

Exceptions

There are some exceptions where twisting solid wires may not be necessary:

Uninsulated Wires

When using uninsulated wires, it is important to crimp or solder the connections rather than twisting them.

Very Small Wires

For very small solid wires (e.g., 14 AWG or smaller), twisting may not provide significant improvement in the connection quality.

Conclusion:

While the NEC does not explicitly require twisting solid wires before installing wire nuts, it is generally considered best practice to do so for improved electrical connections, better grip, and reduced oxidation. However, there are some exceptions where twisting may not be necessary. Flag for review