Thinking about building an Accessory Dwelling Unit (ADU) on your property? Whether you’re planning a “granny flat” for family in Loomis, a rental unit in Roseville, or a backyard home office in Citrus Heights, the excitement of a new build often gets overshadowed by one critical question: How are we going to power it?
An ADU is more than just an addition; it is a fully functioning second home. At Magic Sun Electric, we specialize in helping homeowners navigate the complex electrical requirements of ADU construction across Sacramento and Placer Counties. From full-service residential electrical work to panel upgrades and efficiency improvements, our team ensures your ADU is powered safely and efficiently.
1. Does Your Current Electrical Panel Have the “Muscle”?
Most older homes in the Fair Oaks and Carmichael areas were built with 100-amp or 125-amp electrical panels. While that was plenty of power in the 1970s, it isn’t enough to support a modern main house plus a new ADU with its own HVAC, appliances, and lighting.
To meet California Electrical Code, we often perform a load calculation to confirm your current service can safely support both dwellings. If your existing system is near its limit, you will likely need an electrical panel upgrade to a 200-amp or 400-amp service to ensure everything runs reliably without nuisance breaker trips.
What Does It Cost to Power an ADU?
Electrical costs for an ADU can vary widely depending on your existing service, trenching distance, and utility requirements. In the Greater Sacramento area, many homeowners invest anywhere from $4,000 to $15,000+ for ADU electrical work, including trenching, sub-panels, and utility coordination.
Homes that require a full 200-amp or 400-amp panel upgrade may see higher costs, especially if SMUD or PG&E service upgrades are involved. The best way to get accurate pricing is with a site visit and a load calculation.
Note: All costs vary based on property layout, utility requirements, permitting, and overall project scope.
2. Navigating SMUD and PG&E Requirements
Depending on where you live in the Greater Sacramento area, you are dealing with either SMUD or PG&E. Each utility has specific rules for ADUs, and the right setup depends on how you plan to use the space.
- Sub-panels: Most homeowners choose to run a sub-panel from the main house to the ADU. This is often the most cost-effective way to power a backyard cottage.
- Separate meters: If you are building a long-term rental, you might consider a separate utility meter. This allows the tenant to pay their bill directly, though it requires additional coordination with the utility provider and can increase overall project complexity.
3. Underground Wiring and Trenching
Since many ADUs in Granite Bay and Rocklin are detached structures, power is often routed underground. This requires precise trenching — typically 18 to 24 inches deep, to house the conduit. As licensed C10 electrical contractors, we ensure these lines are safely separated from gas and water lines and installed to current code requirements.
If your ADU will be used as a rental or guest house, it’s also smart to think ahead about EV charging. Adding a dedicated circuit (or a charger-ready setup) during construction is usually far easier than retrofitting later. We can help with EV charging station installation as part of your ADU plan.
4. Meeting Title 24 and Solar Requirements
In California, new detached ADUs must comply with Title 24 Energy Standards. This often includes:
- LED lighting: High-efficiency LED lighting throughout.
- Smart thermostats: To regulate climate control.
- Solar panel integration: Most new ADUs are required to include solar offsets. Because we are the electrical arm of Magic Sun Solar, we can provide a seamless “one-stop” solution for both your wiring and your solar needs.
Many homeowners also take this opportunity to add smart home and low-voltage wiring to their ADU, including Wi-Fi optimization, security cameras, and automated lighting. Planning these features during construction is typically more cost-effective than adding them later.
Depending on your project scope, you may also qualify for local and federal energy programs. Visit our rebates and incentives page to see what savings may be available for panel upgrades, energy efficiency improvements, or EV charging installations.
Frequently Asked Questions (ADU Electrical FAQ)
How many amps does a typical ADU need?
Many ADUs use a 100-amp to 125-amp sub-panel, which is often enough for a kitchen, bathroom, laundry, and climate control (such as a mini-split system). The right size depends on your appliances and whether you plan to add EV charging or other high-demand features.
Does a California ADU require its own solar system?
Under the current California Building Standards (Title 24), many new detached ADUs are required to include solar. In some cases, the requirement can be met by expanding your existing main house solar system. Your builder and local building department can confirm the requirement for your specific project.
Can I run my ADU off a standard extension cord or existing garage circuit?
No. To be legal and permitted in Sacramento County, an ADU must have a permanent, dedicated power source that meets residential building codes.
How long does ADU electrical installation take?
Most ADU electrical projects take anywhere from 1 to 3 weeks depending on trenching, panel upgrades, inspection timing, and utility coordination with SMUD or PG&E.
Can my existing panel support an ADU without an upgrade?
Sometimes, yes — especially if you already have a newer 200-amp panel with available capacity. A professional load calculation is the best way to confirm whether a sub-panel is sufficient or if a service upgrade is needed.
Work With a Licensed Local ADU Electrical Specialist
ADU electrical work isn’t a typical residential upgrade. It requires coordination with building departments, utility providers, and Title 24 energy requirements. As a licensed C10 contractor serving Sacramento and Placer County with extensive experience in panel upgrades, new construction wiring, and ADU power systems, Magic Sun Electric works directly with homeowners, builders, and designers to ensure every ADU is powered safely, efficiently, and up to code from day one.
Planning an ADU in Placer or Sacramento County?
Don’t let electrical hurdles stall your project. Whether you’re in the early permitting phase in Loomis or ready to trench in Roseville, the team at Magic Sun Electric specializes in ADU power solutions and panel upgrades. We’ll help you choose the right approach, coordinate the details, and ensure your ADU is safe, code-compliant, and ready for its first occupant.
Schedule your ADU electrical consultation or call us today at (916) 794-0448.



