Good morning! You've hit on a common point of confusion and debate regarding EV charger installations and 625.40. Let's break down the issue, the relevant code, and how to approach this situation under the 2017 NEC.

Understanding the Issue

The core of the problem lies in interpreting "outlet" and "individual branch circuit" in the context of the Tesla's load-sharing system. You're right to be concerned about 625.40 and how it might apply.

Analysis and Interpretation (Based on 2017 NEC)



625.40 (Individual Branch Circuit)

This section is designed to prevent overloads and ensure adequate capacity for EV charging, given the high and sustained loads involved. The intention is safety.

"Outlet" Definition

As you pointed out, the definition of "outlet" is critical. You're right to question whether a junction box used solely as a splice point constitutes an "outlet" under the code's intent.

Tesla Load Sharing System

The Tesla system is designed to manage the total load and prevent overloading the circuit. The master charger communicates with the slave, dynamically adjusting charging rates to stay within the circuit's capacity. This is key to the argument.

Arguments For and Against Permitting This Installation



Argument Against (Strict Interpretation)

The most literal reading of 625.40 would say you cannot connect two Tesla chargers, even with load sharing, to a single branch circuit, because the junction box is technically an "outlet" feeding two pieces of utilization equipment (the chargers). This is a very conservative interpretation. Your local inspector might take this stance, so be prepared to discuss your reasoning.

Argument For (Applying the Code's Intent)



The Load Management

The Tesla system's load-sharing capability provides a level of safety and control that arguably meets the intent of 625.40. The circuit will not be overloaded, as the master charger prevents it.

Junction Box as a Splice Point

You can argue that the junction box, in this specific application, is not an "outlet" in the traditional sense. It's merely a splice point to facilitate the load-sharing communication and power distribution, with the load sharing function being the most important aspect. It does not serve as a point where other devices can be plugged in.

Manufacturer's Instructions

Following the manufacturer's installation instructions is generally a good practice, and Tesla clearly intends this load-sharing configuration.

How to Proceed (Recommendations)


Consult Your Local Inspector Before Installation

This is the most important step. Explain the Tesla load-sharing system, show them the documentation, and present your interpretation of 625.40. Get their approval in writing if possible. Be prepared for them to say no, but presenting a well-reasoned argument increases your chances of approval.2.

Document Everything

Keep detailed records of the Tesla installation instructions, your discussions with the inspector, and any approvals received.3.

Install According to Tesla Instructions

If you receive approval, meticulously follow Tesla's installation guidelines.4.

Consider Alternative Solutions (If Necessary)

If the inspector rejects the shared circuit approach, you have these options:

Run Two Separate Circuits

The simplest and most code-compliant solution is to install two dedicated branch circuits, one for each charger. This eliminates any ambiguity regarding 625.40.

Load Management System

Consider a third-party load management system. Some systems are specifically designed to manage multiple EV chargers and may be more readily accepted by inspectors.

Key Points to Emphasize to the Inspector



Safety

The Tesla system prevents overloading the circuit through its load-sharing capability.

Manufacturer's Intent

Tesla designed this system to be used with a shared circuit (under controlled conditions).

Compliance with Intent

While a strict interpretation might raise concerns, the intent of 625.40 – to prevent overloads and ensure safety – is met by the Tesla system.

In Summary:

The acceptability of this installation under the 2017 NEC is ambiguous and ultimately depends on your local inspector's interpretation. A proactive discussion with the inspector, a well-reasoned argument based on the Tesla system's safety features, and thorough documentation are essential. If the inspector remains unconvinced, installing two separate circuits is the safest and most code-compliant alternative. Good luck! Flag for review