Rooster Apartments — Multi-Charger EV Retrofit (EV-2782)

Client: Resound Energy
Location: Seattle, Washington
Project Type: EV Charging Infrastructure Retrofit
PE Stamp: WA PE 55998 • OR PE 108239PE

Project Overview

Rooster Apartments needed a fully engineered EV charging retrofit that could support (20) Wallbox units across multiple shared circuits while minimizing electrical upgrades and avoiding a full service replacement. The client required a fast, clear design aligned with Seattle City Light and NEC requirements.

Engineering Approach

PNW Electrical Engineering performed a complete system review including feeder sizing, voltage-drop analysis, conductor derating, and charger grouping to stay within the building’s available capacity. Multi-week data-logging results were reviewed to confirm real peak demand and validate the design assumptions.

Key Technical Highlights

• Shared-circuit configuration with (7) × 60A 2-pole breakers.
• Field-validated feeder lengths used in voltage-drop calculations.
• Charging layout optimized to reduce conduit routing and installation labor.
• Existing house panel capacity confirmed using data-logging.
• Design aligned with NEC 625 and local AHJ requirements.

Deliverables

• PE-stamped engineering package.
• One-line diagram.
• Voltage-drop calculation sheets.
• Load evaluation summary.
• Cable and conduit schedule.
• Panel schedule with charger grouping.
• Installer notes for Resound Energy’s field team.