Okay, let's break down the Tesla charger wiring and address your concerns. You're right to be cautious, and your existing customer relationship is understandable.

Understanding Continuous Load Definition

A "continuous load" is defined by the NEC (National Electrical Code) as a load where the maximum current is expected to continue for

3 hours or more. This is a critical distinction because it affects the required ampacity of the wiring and the breaker size. Tesla Charger Application

Yes,

charging an electric vehicle is absolutely considered a continuous load. A Tesla (or any EV) can easily draw its maximum charging current for hours at a time.

Sizing Wire and Breaker for a 48-Amp Continuous Load

Because it's a continuous load, you need to upsize the wiring and breaker to handle 125% of the load.1. Calculate 125% of the Load

48 amps 1.25 = 60 amps2.

Wire Size

You must use wire rated for at least 60 amps. Given the current capacity,

#6 AWG copper is likely too small, despite your instructions. #6 copper is typically rated for 55 amps at 60C, and 75 amps at 75C. Always check the ampacity rating of the specific wire you're using, based on its insulation type and the temperature rating of the terminations in the breaker panel and the charger. (Use the lowest temperature rating of any connection points in the circuit.) More than likely you would need to use #4 AWG copper. This is generally rated for 70 amps at 60°C, 85 amps at 75°C, or 95 amps at 90°C. Important

It is critical that the wire you use is suitable for the terminations in both the panel and the Tesla charger. Some devices may limit you to 75°C or 60°C ratings.3.

Circuit Breaker

You need a circuit breaker rated for at least 60 amps.

You can use a 60 amp breaker, but you will not be able to use the full 48 amps for charging! Important Considerations on Breaker Selection



Tesla Recommends a 60 Amp Breaker Tesla generally recommends a 60 amp breaker for a 48 amp charging setup.4. Ground Wire

The ground wire size is based on the size of the circuit conductors, according to NEC Table 250.122. For #4 copper conductors, you'll need a

#8 AWG copper ground wire. Your original assessment was correct on this.

Summary of Recommended Materials (Assuming Copper and 75°C Terminations) Circuit Breaker

60-amp, 2-pole (for 240V)

Conductors

#4 AWG Copper (check ampacity for your insulation type and temperature rating)

Ground

#8 AWG Copper

Wiring Method

Use the appropriate wiring method for your local codes and installation (e.g., conduit, cable). Make sure the wire is rated for the installation.

Important Considerations and Best Practices



Local Codes and Permits

This work requires permits and inspections in most jurisdictions. Make sure you pull the necessary permits and follow all local electrical codes. This is especially important since you're doing this as a favor.

Tesla Charger Installation Manual

Always refer to the Tesla Charger installation manual for specific requirements. There may be nuances or specific instructions that Tesla provides.

Wire Type

The ampacity of the wire is affected by its insulation type (e.g., THHN, THWN, XHHW). Use wire rated for the environment (dry, wet, etc.) and the temperature rating of the terminations.

Distance

For long distances, voltage drop becomes a significant concern. Use a voltage drop calculator (available online) to ensure that the voltage at the charger doesn't drop below acceptable levels when the charger is drawing its maximum current. If voltage drop is excessive, you may need to increase the wire size further.

Professional Advice

Given that you're essentially retired and unfamiliar with Tesla chargers,

strongly consider consulting with a licensed electrician who is experienced with EV charger installations. They can assess the specific situation, ensure compliance with local codes, and provide the safest and most reliable installation. This can also protect you from liability. Direct Wire vs. Outlet

You mention direct wiring. This is generally the preferred and safest method. If you were to use an outlet, it would need to be a NEMA 14-50. However, NEMA 14-50 outlets are often problematic for EV charging due to the high continuous current draw, and direct wiring is much more reliable.

Tesla Wall Connector Gen 3 Dip Switches The Tesla Gen 3 Wall Connector has dip switches in it to set the proper amperage for the circuit, or to limit the charging amperage of the Tesla Wall Connector. This is for safety and optimal performance.

In Summary

While your customer's request of using #6 AWG copper and a 50 amp breaker might work, it's not compliant with code for a 48-amp continuous load.

Code requires you to use a 60 amp breaker, with #4 copper wire. And absolutely consult with a local, licensed electrician before proceeding. It's better to be safe and code-compliant than to risk a fire or other hazard. This is also important for liability reasons. Flag for review