Powering Your ADU: The Electrical Phase
With the framing complete, it's time to bring power to your ADU. The electrical phase involves running wires, installing boxes, and setting up the systems that will power everything from lights to appliances.
Electrical Service Options
Sub-Panel (Most Common)
Your ADU gets its own electrical sub-panel fed from your main home's electrical panel. This is the most cost-effective option if your main panel has enough capacity (typically need 60-100 amps available).
Separate Meter
Your ADU gets its own utility meter and main panel, completely independent from your home's electrical. This costs more (a property-specific written estimate for the meter setup) but is ideal if:
- Your main panel doesn't have spare capacity
- You want your tenant to pay their own electric bill
- You plan to sell the ADU separately in the future
The Electrical Rough-In Process
Step 1: Panel Installation
The electrical panel (usually 100-amp for an ADU) is mounted and the main feeder wires are run from the source.
Step 2: Circuit Layout
Wires are run through the wall and ceiling framing to every location that needs power:
- Outlets: Code requires outlets every 12 feet along walls, and within 6 feet of every door opening
- Kitchen circuits: Dedicated 20-amp circuits for countertop outlets, refrigerator, dishwasher, and garbage disposal
- Bathroom circuits: GFCI-protected 20-amp circuits
- Lighting circuits: Separate circuits for lights, typically 15-amp
- HVAC circuit: Dedicated circuit for the heat pump/AC unit
- Smoke/CO detectors: Hardwired with battery backup, interconnected throughout
Step 3: Special Systems
- Doorbell and intercom wiring
- Cable/internet low-voltage wiring
- Smart home infrastructure (if desired)
- EV charger pre-wire (future-proofing your ADU)
Step 4: Electrical Inspection
The city inspector checks all rough electrical work before walls are closed up. They verify:
- Wire sizes match circuit ratings
- Proper box fill (not too many wires in each box)
- GFCI and AFCI protection where required
- Grounding and bonding are correct
- Smoke/CO detector placement meets code
Code Requirements You Should Know
- GFCI protection: Required in kitchens, bathrooms, garages, outdoors, and laundry areas
- AFCI protection: Required in bedrooms, living rooms, and most habitable spaces
- Tamper-resistant outlets: Required in all locations
- LED lighting: Required for Title 24 compliance
- Bathroom exhaust fans: Must be wired to a timer or humidity sensor
Budget Expectations
Electrical work for an ADU requires a property-specific written estimate depending on the size of the unit and complexity of the installation.
Pro Tips
- Plan outlet locations carefully — think about where furniture will go and where you'll need to plug things in
- Add more outlets than code minimum — it's cheap during rough-in, expensive after drywall
- Pre-wire for the future — run conduit or extra wires for potential EV chargers, solar, or additional circuits
- Use LED recessed lights — they're energy efficient, look clean, and satisfy Title 24
Coming Up Next
Day 9: Plumbing — bringing water in and waste out, plus the water heater, fixtures, and gas lines that make your ADU fully functional.
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Vision ADU handles all electrical work with licensed electricians. Get your free estimate.
Related Vision ADU Resources
- How to Build an ADU, Day 10: Insulation & Drywall
- How to Build an ADU, Day 11: HVAC — Heating & Cooling
- How to Build an ADU, Day 12: Roofing
- How to Build an ADU, Day 13: Bathroom Tile & Shower
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