Bethesda 200A Panel Upgrade + Tesla Wall Connector
Case study: how Flash Power LLC upgraded a 1958 Bethesda rambler from 100A to 200A and installed a Tesla Wall Connector — permitted, inspected, and completed in one day.
Project overview: The homeowners on a 1958 Battery Park rambler had just taken delivery of a Tesla Model Y and discovered their 100A Federal Pacific panel wouldn't safely support Level 2 charging. Flash Power LLC replaced the panel with a 200A Square D QO service, added whole-home surge protection, and installed a Gen 3 Tesla Wall Connector in the garage — all in a single day with a Montgomery County DPS permit closed the following week.
Key details
- Customer: Owner-occupant single-family home
- Scope: Panel + service + Wall Connector
- Location: Bethesda, MD 20816
- Permit: Montgomery County DPS
- Duration: 1 day on site
- Result: 48A charging + full-home surge protection
Project overview
The homeowners contacted Flash Power LLC after their Tesla delivery scheduler flagged that their existing 100A Federal Pacific Stab-Lok panel could not safely handle a Level 2 EV charger. We visited the same week, completed a load calculation, and provided a firm written quote covering panel replacement, meter base, whole-home surge protection, and a Gen 3 Wall Connector install.
Customer type
Owner-occupant, single-family Bethesda home built in 1958. Two Tesla vehicles expected. Long-term homeowners planning to stay 10+ years.
Scope of work
Replace the existing 100A Federal Pacific Stab-Lok panel with a Square D QO 200A load center. Replace the rusted meter base. Install a Type 2 whole-home surge protection device at the main. Run a dedicated 60A circuit to the attached garage and mount a Gen 3 Tesla Wall Connector. Pull Montgomery County DPS permit and close inspection.
Challenges
The Federal Pacific panel had two double-tapped breakers and one breaker showing signs of past thermal damage. The meter base was rusted and needed replacement — which required Pepco coordination for a service disconnect. The garage had no existing 240V circuit, requiring a 40-foot conduit run from the panel to the mounting location.
Solution
Coordinated Pepco service disconnect at 8am. Removed the Federal Pacific panel and rusted meter base. Installed new Square D QO 200A panel, whole-home SPD at the main, and a new Milbank meter base. Pepco reconnected by noon. Ran the new 6-3 NM-B garage circuit through the basement ceiling and out to the garage wall, then mounted and configured the Wall Connector at 48A. Power restored to the whole home by 1pm; charger commissioning complete by 3pm.
Products installed
Square D QO 200A 40-space load center. Square D QO surge protection device (Type 2, at the main). Milbank 200A meter base. Gen 3 Tesla Wall Connector (48A configuration). Copper THHN service entrance conductors.
Results
The home now supports Level 2 charging at 48A (adding ~40 miles of range per hour to a Tesla Model Y). The Federal Pacific panel — a documented fire risk — is gone. Whole-home surge protection extends the life of every electronic in the house. Permit closed by MCDPS within 5 business days. Total cost was within the initial written estimate with zero change orders.
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