ADU Electrical Requirements in California

What are The ADU Electrical Requirements in California?

When designing an accessory dwelling unit (ADU) in California, careful electric planning is essential for both safety and efficiency. Beyond simply powering the home, the state’s Title 24 regulations, enforced by local building departments, ensure ADUs operate within required standards. These laws reduce energy consumption, lower the homeowner’s utility bills, and also promote environmental sustainability. Specific electrical requirements for ADUs in California include: 

• Electrical Panel Size: The amperage requirement for an ADU varies based on its size and electrical demand. A 100-amp panel is typically sufficient but larger units or those with high electrical needs may require a larger panel.
• Circuits: At a minimum, ADUs must have two small appliance circuits. One should be a dedicated laundry circuit and the other a dedicated bathroom circuit.
• Lighting Requirements: New and replaced hardwired lighting must meet high efficacy standards. Recessed downlights should not have screw bases and enclosed luminaires are required.
• Solar Panel Installation: Detached and non-manufactured ADUs in Southern California must be equipped with solar panels.
• Main Service Panel Upgrade: The electrical main service panel (MSP) may need to be upgraded to accommodate the additional electrical load from the ADU.
• Energy Efficiency Compliance: ADUs must comply with California’s Title 24 energy efficiency standards. Energy Commission-approved computer methods can help ensure compliance.

Why Proper Electrical Planning is Essential for ADUs in California

Adhering to California’s Electrical Code (Title 24) is a vital part of an ADU project. Failing to comply with these regulations can lead to serious safety risks such as electrocution or fire hazards, and can cause significant project setbacks, including expensive repairs, reworking installations, or even legal complications. By following the ADU electrical requirements in California from the start, homeowners can avoid these issues, saving both time and money—setting their project up for success. 

Does an ADU Need its Own Electrical Panel?

There’s a common misconception that an ADU can always share the main house’s electrical panel. In most cases, however, ADUs require an upgraded panel to handle the increased electrical load from appliances, lighting, and HVAC systems. A dedicated panel or subpanel may also be necessary in some cases. 

In San Diego, SDG&E’s guidelines may require a separate meter for an ADU, especially if the unit is a rental or the electrical load is too high. Homeowners can apply for separate meter services through SDG&E but should be aware the installation costs can add up. As a more affordable option, homeowners might consider installing a sub-meter, which allows the ADU to share the main panel while still tracking usage separately. 

How Many Amps Does an ADU Need?

The amp requirement for an ADU depends on its size and the electrical systems it needs to support. Most ADUs need 100 to 200 amps to run efficiently, though smaller units with fewer appliances may only require 60. Important factors affecting the amp requirement include the presence of HVAC systems, kitchen and laundry appliances, and lighting needs. Consulting an electrician early helps prevent circuit overloads or unexpected upgrades later. 

How to Calculate the Electrical Load for Your ADU

When calculating the electrical load for your ADU, consider the types of appliances you’ll be using, as they significantly impact power usage. Major appliances like stoves, ovens, refrigerators, and laundry machines need dedicated circuits and contribute more to the load than smaller items like lighting. HVAC systems also require considerable power. If your ADU includes an electric vehicle (EV) charger, it may need a separate 30 to 50-amp circuit. 

It’s also important that the ADU’s lighting setup complies with ADU electrical requirements in California, specifically regarding Title 24 regulations for energy efficiency. Using a load calculator or consulting an electrician will help you accurately calculate the total electrical demand, helping prevent system overloads or future complications. 

Key Electrical Components Required for ADUs in California

These are the basic electrical requirements for ADUs in California, but every home is different. It’s a good idea to talk with a local electrician who can look at your specific project and help set things up safely and efficiently. For ADUs to function safely and efficiently, several key electrical components are needed:

• Wiring: Wiring must meet California Electrical Code standards for safety and reliability.
• Outlets: Installed according to building codes, typically every six feet in living areas. For safety, GFCI outlets are required in kitchens, bathrooms, and exterior spaces to prevent hazards.
• Circuits: High-power appliances like HVAC systems and laundry machines need dedicated circuits. General-purpose circuits handle lighting and smaller appliances.
• Panels: The ADU connects to the main electrical panel, but if the load is too much, a subpanel may be needed. Most ADUs require 100-200 amps, although smaller units may need as little as 60. Sub-metering or installing a separate panel may be required if the main panel can’t handle the demand.

What Are the Typical Costs for Electrical Service Upgrades in San Diego?

If the existing panel cannot handle the added load of the ADU, upgrades will be necessary. In San Diego, these generally cost between $1,500 and $5,000, depending on the ADU’s size and appliances installed. Solar panels can reduce future energy costs but may raise initial installation expenses. Additional costs may arise if trenching or other infrastructure work is required for the upgrade.

SDG&E handles utility service upgrades, a process that can take a few weeks to several months, depending on their availability and the local permitting process. Permits are required to verify that the upgrades comply with California’s electrical codes.

Title 24 Compliance and Solar Panel Requirements

Under California’s Title 24 regulations, ADUs are required to be solar-ready, meaning they must have the space and infrastructure to support solar panels, even if they aren’t installed right away. This requirement is part of the state’s commitment to energy efficiency. However, there are some exemptions, such as when an ADU is built within the footprint of an existing structure (like a garage or basement) or if the property’s roof orientation or shading makes solar panels impractical.

San Diego homeowners may also qualify for local solar rebate programs and incentives, which can help offset installation costs (see below!) Combined with long-term savings on energy bills, these incentives make solar panels a smart investment for ADU homeowners looking to reduce costs while meeting Title 24 requirements.

Solar Panel Incentives for ADUs in Greater San Diego

Homeowners with ADUs in San Diego can take advantage of several solar incentive programs that help lower the cost of installation and offer long-term savings. These programs not only make solar energy more affordable but also help homeowners comply with Title 24 regulations while reducing long-term utility costs.

• Federal Solar Investment Tax Credit (ITC): ADU owners can claim a 30% federal tax credit on solar panel installations, significantly reducing upfront costs.
• SDG&E’s Net Energy Metering (NEM) Program: ADU owners can sell extra solar energy they generate back to the grid and earn credits on future utility bills.
• San Diego Solar Equity Program: This program provides financial assistance for solar installations to low-income homeowners, covering up to 100% of installation costs.
• California Solar Initiative (CSI): This program provides rebates for solar installations, particularly for residential and low-income households, reducing the initial investment.

Utility Connections for ADUs in Greater San Diego

Setting up utility connections for an ADU involves several key steps. Although the process may seem complex, working with SDG&E will keep the construction on track. Here’s how it works from start to finish:

• Initial Consultation with SDG&E: SDG&E will assess the ADU’s electrical needs and determine if a panel upgrade or sub-panel is required.
• Submit Application: Homeowners must submit an application for service upgrades, including project details and an electrical load report.
• Utility Design Plan: SDG&E will review the application and create a utility plan, which may involve choosing between overhead and underground power lines. Overhead lines are more affordable but may face restrictions, while underground lines can cost $5,000 to $10,000.
• Panel Upgrades and New Connections: If the ADU’s electrical load exceeds the main panel’s capacity, a panel upgrade will be required, costing between $1,500 and $5,000.
• Permitting and Inspections: After the design is finalized, permits and inspections are needed to verify compliance with safety codes.

How to Work with SDG&E on ADU Utility Projects

Working with SDG&E on ADU electrical service upgrades requires a detailed process. The key steps are as follows:

• Initial Inquiry & Consultation: Begin by contacting SDG&E to discuss your ADU project. During this initial consultation, they will assess whether your existing electrical service can handle the added load or if a panel upgrade or a separate meter is needed.
• Application Process: Submit an application to request a service upgrade or a new meter for your ADU. Include key details like the size of the ADU, the number of appliances, and any special equipment (like HVAC systems, EV chargers, etc.). Include your electrical load calculations, which are typically provided by a licensed electrician, as part of the application process.
• Review & Approval: SDG&E will review the application to determine the upgrades needed, and may conduct a site visit to assess the existing service and if any upgrades or a separate meter are needed.
• Timeline: The entire process from application to final utility connection can take several weeks to a few months, depending on the complexity of the project, permit approvals, and SDG&E’s workload. Local city or county permits must be secured before upgrades can begin, which can take considerable time, especially if additional electrical panel work or trenching for underground lines is required.
• Cost Considerations: Panel upgrades typically range from $1,500 to $5,000 depending on the required capacity (100 to 200 amps) and the scope of work. Installing a separate meter can add another $500 to $1,500 to the overall expense. If trenching or upgrading utility lines is necessary, this can further increase the cost, with prices varying based on site conditions.
• Panel Upgrade vs. Separate Meter: SDG&E will advise whether to upgrade the existing panel or install a separate meter based on the ADU’s electrical load. If the total electrical demand of the main house and ADU exceeds the current panel’s capacity, a panel upgrade will be necessary. If the ADU is a rental, however, a separate meter is often recommended for independent billing.
• Coordination with SDG&E: Once approved, SDG&E will coordinate with the homeowner or contractor for installation. Once complete, inspection by both SDG&E and local building authorities confirms compliance with the California Electrical Code.

Choosing a Qualified Electrical Contractor for Your ADU

When choosing an electrical contractor for your ADU project, finding someone with the right experience is critical. Look for a licensed contractor who is certified in California, and familiar with both the state’s Title 24 energy efficiency requirements and SDG&E’s guidelines for ADU electrical service. The contractor should also have a strong understanding of local building codes and ADU-specific regulations, especially in areas like San Diego, where SDG&E has specific processes for panel upgrades and utility connections. Finally, experience matters, so don’t be afraid to ask the contractor for references or examples of previous ADU projects to confirm their experience in handling the electrical needs of smaller, secondary units.

At Better Place, we have the experience to navigate both state and local ADU regulations. Our full-service project management covers everything, from design through construction, keeping your project on track and compliant with California’s Title 24 energy requirements and SDG&E guidelines. From zoning to utility connections and permits, we manage each step of the process, helping you get your ADU project off the ground while staying compliant with all regulations.

Planning Your ADU’s Electrical Setup

We also understand that planning your ADU’s electrical systems can feel overwhelming. That’s why we’ve strived to make the process as straightforward as possible. It’ll go a little something like this:

• Evaluate the total power needs for the ADU, considering factors like the number of appliances, HVAC systems, and potential EV chargers.
• Determine amp requirements based on the electrical load, whether it’s 60, 100, or 200 amps, and whether a panel upgrade or subpanel is needed.
• Coordinate with SDG&E to handle utility service upgrades, including decisions on overhead vs. underground power lines, and if a separate meter is necessary.
• Make sure the ADU is solar-ready and meets the energy efficiency standards outlined in California’s Title 24 regulations.
• Hire a qualified contractor experienced in local codes, Title 24, and SDG&E requirements to handle installation, permits, and inspections.

With our extensive experience, we’re the perfect partner to help you navigate the complexities of ADU electrical requirements while making sure your project is safe, cost-effective, and compliant with state and local regulations.

Ready to finally bring your ADU idea to life? Contact us today for a free consultation<. Let’s turn your vision into a reality!