A Second EV Without A Second Service Entry.
The homeowners had bought a Model Y to join the existing Model 3 already charging on a Wall Connector installed by a previous contractor. On paper, two simultaneous 48A chargers (96A continuous) would exceed safe margins on their existing 200A panel — particularly during summer when the AC and oven also draw heavily. The straightforward path was a service upgrade to 320A. We didn't think that was necessary.
Dynamic Load Share, Not A Service Upgrade.
We replaced the existing Wall Connector with two new ones daisy-chained on a shared 60A circuit, with the second wired as a load-sharing slave to the first. Tesla's firmware then automatically splits the available 48A between both cars when both are plugged in, and gives all of it to a single car when the other isn't.
We added a Span smart panel at the same time, giving the homeowners circuit-level visibility into household load and the ability to set "always-on" priorities. Total real-world impact: each car still gets ~25 miles of range per hour while charging together, full speed when charging alone, and the family avoided a $4,800 service upgrade.
| Service Rating | 200A · existing, retained |
|---|---|
| EV Circuit | 60A double-pole AFCI/GFCI, #6 AWG THHN copper |
| Chargers | 2× Tesla Wall Connector (Gen 3) · load-shared |
| Effective Draw | 48A shared continuous, 24A per vehicle when paired |
| Conduit | 3/4" EMT exposed, painted to match garage trim |
| Smart Panel | Span 32-circuit, replaced existing Eaton CH |
| Permit | City of Austin Electrical Permit · pulled by VoltSync |
| Inspection | Passed first-time · February 28, 2025 |
Two Cars Charged Overnight. No Service Upgrade. Visibility For The First Time.
The family had been guessing at their household power use for a decade. With the Span panel, they now see actual draw per circuit on their phones — and have run the dishwasher and the dryer at noon for the first time without anxiety. We stop by annually for a maintenance look at the lugs and torque check. Both chargers and the load-share firmware have run without intervention since install.
Considering One Or Two Chargers?
We'll come look at your panel, run the load math, and tell you whether load-sharing will save you a service upgrade.