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When installing a Tesla charger, it is important to choose the correct wire size for the electrical circuit.
In this blog post, we will explore the appropriate wire size for a 60 Amp Tesla charger, as well as any other considerations you should keep in mind during the installation process.
Recommended Wire Size for a 60 Amp Tesla Wall Connector
The recommended wire size for a 60 Amp Tesla Wall Connector is based on the size of the breaker, not the expected load. The consensus is to use #4 Cu (copper) or #2 Al (aluminum) wire[1].
Additionally, it is not necessary to use a 3-wire+ground cable unless you want to feed a sub-panel to power other loads or have 3-phase power and want to power 2-3 Wall Connectors independently.
Since the distance is short enough that voltage drop won’t matter, the type of cable or wire depends on whether the installation is indoor or outdoor. The most versatile and cost-effective option is to feed a sub-panel with #2 aluminum wire, which is cheaper than copper and has the appropriate lugs for aluminum wire. If a sub-panel is not desired, #4 aluminum wire or #6 copper wire can be used[1].
If using NM type cable, #4 NM copper wire is recommended for indoor installations. Ultimately, it is important to follow the paper instructions provided by the device’s UL listing, as specified by NEC 110.3(B)[1].
Wire Size for 50 Amp and 60 Amp Circuits
The correct wire size for both a 50 Amp and 60 Amp circuit is 6 AWG Cu or 4 AWG Al, which allows for rounding up to the next available breaker size[2]. It is not recommended to use 8 AWG Cu wire as it may not be sufficient for continuous loads.
While there may be a cost difference between 50 Amp and 60 Amp wire, it is important to use the correct wire size to avoid having to redo the installation later. Pricing questions are difficult to answer without sufficient information about location and purchase details[2].
Wire Gauge Recommendations for Tesla Chargers
The difference between the gauge wire that Tesla recommends for their chargers and the gauge wire recommended in an online chart is due to the latter being a chart for marine DC power systems which operates at 12 or 24 volts, while Tesla chargers use 240 volts[3].
Voltage drop calculations on a voltage drop calculator website indicate that for a 240V circuit, 6 AWG copper wire is enough to support a 40 amp load for up to 150 feet with a worst-case voltage drop of only 1.98%[3].
If you want to future-proof your installation and anticipate a 100A charger, it is recommended to use #1 aluminum wire, which will support the increased amperage without the risk of overheating. A conduit system that would allow larger wire to be pulled if necessary is recommended, with 1-1/4″ or 1-1/2″ conduit being the preferred sizes. Finally, the MFG instructions of the equipment being installed override NEC guidelines for wire gauge sizing[3].
Future-proofing Your Installation
A user planning to install a wire from an electrical sub-panel to a garage for a 240V 6-50 outlet for use with a Tesla Mobile Connector wanted to future-proof the installation for a possible second EV and considered installing two Tesla Wall Chargers, which each max out at 48A[4].
The expert recommended using #2 aluminum wire, which can support 80A and multiple EVSEs, and warned against using NM or UF types, which require the 60C column for calculating ampacity, instead of the 75C column used for other wire types[4].
The expert also explained how to commission an EVSE to charge at an arbitrary rate and use power-sharing to allow each car to charge at its full capacity. The expert recommended upgrading the existing subpanel and feeder to support the increased load and provide more breaker spaces for future expansion[4].
Adding a 60 Amp Breaker Line for Tesla Wall Charger to a 125 Amp Subpanel
A user was hoping to add a 60 Amp/220V circuit for their Tesla Wall Charger to a 125 Amp subpanel supplied by #2 copper wire and was unsure if their subpanel could handle the load[5]. The first answer explained that the Tesla Wall Connector allocates charge current “soft”, meaning the current is programmable.
It’s not actually the charger. When installing the Wall Connector, the amps of the circuit can be configured, which can be any value, from 20 amps to 80 amps. The Tesla Wall Connector doesn’t actually use neutral, so it is better to hardwire it[5].
The user must follow a procedure called a Load Calculation, which is defined in NEC Article 220, to determine how much their house can support[5]. They must do the Load Calculation twice: on the entire service, and on the loads and square footage powered by the subpanel.
The lesser of the two will indicate the amps they can commission when they set up the Tesla Wall Connector. The municipality will have a worksheet, which they derived from Article 220, but it is best to ask the local municipality for their rules[5].
The second answer explains that, based on the current breakers the user has, they can add another 50 Amp load. The subpanel serves approximately 800 square feet of space, and the home is gas heated, with the water heater and dryer also being gas[5].
The user should hardwire the Wall Connector as it has GFCI protection built in, and they don’t need anything larger than the feeder requirements[5].
In summary, the user can use a 60 Amp circuit coming out of their subpanel, but it is best to do the Load Calculation to determine the maximum amps they can commission for their Wall Connector. As the home is gas heated, the load on the subpanel is not high, and the user can install a 60 Amp circuit for the Wall Connector. It is better to hardwire the Wall Connector, as it doesn’t actually use neutral[5].
Final Thoughts
When installing a 60 Amp Tesla charger, the recommended wire size is #4 Cu (copper) or #2 Al (aluminum) wire. The type of cable or wire depends on whether the installation is indoor or outdoor, and whether a sub-panel is being used. Future-proofing your installation may involve using larger wire sizes and upgrading the subpanel to support increased load and provide more breaker spaces for expansion.
When adding a 60 Amp circuit to a subpanel, it is crucial to perform a Load Calculation to determine the maximum amps that can be commissioned for the Tesla Wall Connector. Following these guidelines will ensure a safe and efficient installation of your Tesla charger.