The Situation
The homeowner purchased a Rivian R1S and wanted to charge at home rather than rely on public stations. They had gotten a quote from another contractor who planned to install a 50-amp circuit directly into the existing 125-amp panel, treating the available breaker slot as sufficient.
When Matthew visited the property off Los Osos Valley Road for the free assessment, he measured the actual load on the existing panel and found the available headroom was dangerously thin. Running a 50-amp EV circuit at full draw alongside the existing HVAC, water heater, and kitchen loads would push the panel to the edge of its rating under realistic conditions. The service entry conduit also showed weather damage from a prior irrigation installation nearby.
"He could have just done the charger and collected his check. Instead he showed me the load calculation and explained why the panel was the real issue. That kind of honesty is hard to find."
Homeowner, Los Osos Valley Road area, San Luis Obispo
The new 200-amp Square D panel after installation, before the door was closed for final inspection.
Scope of Work
We filed a single permit with the City of San Luis Obispo Building Division at 919 Palm Street covering both scopes. Filing them together reduced total permit fees and meant only one inspection visit was required for sign-off on both the panel and the charger circuit.
- 200-amp Square D QO panel replacing existing 125-amp unit
- Service entry conduit replaced from weatherhead to meter base
- All circuits transferred and fully labeled on new directory
- 50-amp dedicated EV circuit, 6 AWG copper, home run to panel
- NEMA 14-50 outlet installed in garage at owner-specified height
- Rivian-compatible Level 2 charger mounted and tested
- City of SLO permit filed, single combined scope, inspection passed
Completed Level 2 charger installation. The Rivian charges overnight at full speed on the 50-amp circuit.
Why the Panel Upgrade Mattered
The Rivian R1S draws up to 48 amps on a Level 2 connection. That single circuit alone represents nearly 40 percent of a 125-amp service. California residential electrical code requires a 25 percent headroom buffer on residential feeders under continuous load conditions. Squeezing both would have put the panel in violation of code and created a real risk of nuisance tripping and accelerated component wear on an already aging service.
The 200-amp upgrade also future-proofed the property for the homeowner's stated plans: a rooftop solar installation planned for the following year and a possible heat pump HVAC replacement. The new panel has capacity for both without any additional service work.
The Outcome
Project Results
- 200-amp service fully operational, all circuits labeled
- Rivian R1S charging to full overnight at 48-amp draw
- City of SLO inspection passed on first visit, no corrections
- Panel capacity confirmed for planned solar and heat pump additions
- Homeowner received PG&E $800 EVSE rebate post-completion
- Total timeline: first call to inspection sign-off in 11 days including permit
Total investment was $6,200 including all labor, materials, and permit fees. The homeowner subsequently applied for the PG&E $800 EVSE rebate and the 3CE Electrify Your Ride program, which paid out approximately $2,000 combined, reducing net out-of-pocket cost to roughly $3,400.
"Two days, one inspection, one check. The Rivian charges every night now and we have room on the panel for solar next year. Exactly what we needed."
Homeowner, San Luis Obispo, CAClient name withheld at request. Results vary. Prior results do not guarantee similar outcomes.