Complete Guide to Electrical Panel Requirements for Accessory Dwelling Units (ADUs)
As Accessory Dwelling Units (ADUs) become increasingly popular across California, many homeowners and builders are asking: “Do ADUs need a separate electrical panel?” The short answer is—it depends. Below, we break down everything you need to know about electrical panel requirements for ADUs, whether you’re building a detached unit in your backyard or converting a garage into a livable space.
✅ When Is a Separate Electrical Panel Required for an ADU?
In California, most ADUs require a dedicated electrical panel or subpanel depending on:
The size of the unit
The number of circuits required
Whether the existing main panel can support additional load
The layout and distance from the main home
Scenarios that require a separate panel:
Detached ADU or new construction: A new panel or subpanel is almost always required for compliance and safety.
Limited capacity in main panel: If your primary home’s panel cannot accommodate more breakers, a new panel must be added.
Permitting and inspection requirements: Los Angeles and many surrounding cities prefer or mandate separate panels for ADUs for clarity during inspection.
🔌 What Are the Options for Powering an ADU?
You generally have three options depending on the scope of the project:
1. Install a Brand-New Main Panel for the ADU
Typically for detached units on large lots
Allows the ADU to be metered separately (optional)
Increases future flexibility and resale value
2. Add a Subpanel Connected to the Main Home’s Panel
The most common method for both attached and detached ADUs
Cleaner integration, especially if you don’t need a second meter
Subpanel allows control over circuits in the ADU without impacting the main home
3. Share the Existing Panel (Only If Code Allows)
Only possible in smaller conversions with low power requirements
Not recommended for most builds due to load calculations and future code limitations
Often not accepted during inspection or permitting in Los Angeles
🔍 Can an ADU Have Its Own Electrical Meter?
Yes. You can request a separate utility meter for your ADU. This is common if:
You plan to rent the ADU to tenants
You want each unit to pay for its own electricity
The utility company and local building department approve the setup
Note: Not all cities require a second meter. Los Angeles allows subpanels powered from the main home without separate metering in most cases.
📏 Electrical Panel Size Requirements for ADUs
Typical service size needed:
100-amp subpanel: Ideal for small to medium-sized ADUs
200-amp main panel upgrade: Often required if the main home’s panel can’t handle the additional load
50-amp temporary supply: May be acceptable for small studio conversions or detached office spaces (rare)
A load calculation is always recommended to determine the correct panel size based on:
Appliances (e.g. range, dryer, mini-split HVAC)
Lighting
Dedicated circuits (e.g. kitchen, bathroom, laundry)
Who Handles Electrical Panel Installation for ADUs?
At LAProElectrical, we specialize in ADU electrical design, panel installations, and turnkey service packages across Los Angeles and surrounding areas. Whether your project requires a:
New 200-amp panel upgrade
Dedicated subpanel for the ADU
Split service with load calculation and permits
—we handle everything from planning to final inspection.
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📋 Summary: Key Questions Answered
| Question | Answer |
|---|---|
| Do ADUs need their own panel? | Yes, in most cases—especially for detached units. |
| Can I share the main panel with my ADU? | Only if there’s enough capacity and local code allows. |
| What size panel do I need for my ADU? | Typically 100-amp for the ADU; may require 200-amp upgrade for the main home. |
| Do I need a second meter? | Only if you want separate billing or local code requires it. |
| Who installs the ADU panel? | A licensed residential electrician like LAProElectrical. |
Los Angeles CA areas we serve:
We proudly serve all neighborhoods in Los Angeles County. Common areas we service include:
- Agoura Hills
- Alhambra
- Arcadia
- Artesia
- Avalon
- Azusa
- Baldwin Park
- Bell
- Bell Gardens
- Bellflower
- Beverly Hills
- Bradbury
- Burbank
- Calabasas
- Carson
- Cerritos
- Claremont
- Commerce
- Compton
- Covina
- Cudahy
- Culver City
- Diamond Bar
- Downey
- Duarte
- El Monte
- El Segundo
- Gardena
- Glendale
- Glendora
- Hawaiian Gardens
- Hawthorne
- Hermosa Beach
- Hidden Hills
- Huntington Park
- Industry
- Inglewood
- Irwindale
- La Cañada Flintridge
- La Habra Heights
- La Mirada
- La Puente
- La Verne
- Lakewood
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- Los Angeles
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- Temple City
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