5 ADU Electrical Requirements Every Sacramento Homeowner Must Know

Sacramento is in the middle of an ADU boom — and it’s not slowing down. Between 2016 and 2023, California saw ADU permits jump from 1,336 to over 26,900 per year — a 20-fold increase. Right here in Sacramento, homeowners from Land Park to Natomas are adding backyard cottages, garage conversions, and detached granny flats at a pace our city hasn’t seen in decades. But while the design excitement is real, the electrical side of an ADU project is where things get expensive and complicated fast. Miss a granny flat electrical code requirement or fail to coordinate with SMUD early enough, and you’re looking at months of delays and thousands in unexpected costs. Our team at TNT Electric has wired dozens of ADUs across Sacramento, and this guide breaks down the five non-negotiable ADU electrical requirements Sacramento homeowners must understand before breaking ground.

Table of Contents

1. Separate Electrical Panel or Subpanel Requirement
2. SMUD Separate Meter vs. Shared Meter Considerations
3. Minimum Circuit Requirements for Kitchens, Bathrooms, HVAC, and General Use
4. Title 24 Energy Compliance for New Sacramento ADUs
5. Permit and Inspection Process for Sacramento County ADU Electrical Work

1. Separate Electrical Panel or Subpanel for Your ADU

Every ADU in Sacramento needs its own dedicated electrical panel or subpanel — no exceptions. An ADU has a kitchen, bathroom, HVAC, and often a laundry setup, meaning it needs a properly sized, code-compliant electrical distribution point of its own. You cannot legally power a fully functioning accessory dwelling unit by extending a few circuits from your house.

How big does the panel need to be? Most Sacramento ADUs require between 100 and 200 amps of dedicated capacity. The sweet spot we recommend is a 125-amp subpanel, which covers a mini-split HVAC unit, full kitchen appliances, bathroom circuits, and general receptacles while leaving headroom for future additions like an EV charger or battery storage. A 100-amp panel might pass code, but it leaves your system running near capacity — a real problem when Sacramento’s 100°F summer days push AC to its limits.

Here’s where it gets real: Most older homes in Curtis Park, Tahoe Park, East Sacramento, and Carmichael were built with 100-amp or 125-amp main panels. That was plenty for a single home in the 1960s, but it’s not enough to power a house plus a new ADU. If your main panel doesn’t have enough capacity, you’ll need an electrical panel upgrade to a 200-amp or 400-amp service before feeding a subpanel to the ADU.

Cost ranges: A subpanel installation for an ADU typically runs $1,500–$4,000. If your main panel also needs an upgrade, add $2,500–$6,000. Underground trenching from the main house to a detached ADU adds $1,500–$5,000 depending on distance — Sacramento’s clay-heavy soil makes trenching more labor-intensive in many neighborhoods.

Pro tip: Have a licensed electrician perform a full load calculation before finalizing your ADU design. This adds up every appliance, HVAC unit, outlet, and fixture, converts it to amperage, and confirms whether your existing service can handle both dwellings. We’ve saved homeowners thousands by catching panel capacity issues before permits are submitted rather than during inspections.

2. SMUD Separate Meter vs. Shared Meter Considerations

One of the biggest decisions Sacramento ADU owners face is whether to install a separate SMUD meter or share the existing meter with the main house. Unlike SDG&E in San Diego, SMUD does not mandate a separate meter — California state law (SB-13) prohibits requiring separate utility connections for ADUs. But just because it’s not required doesn’t mean it’s not worth considering.

Shared Meter (Subpanel from Existing Service)

This is the most common and cost-effective approach. Your electrician installs subpanels for ADUs and workshops fed from your existing main panel, and everything runs on a single SMUD account. Best for: family member ADUs, home offices, or situations where you’ll manage the electric bill directly. The downside? You’re on the hook for the ADU’s electricity. A tenant running their AC from June through September can add $150–$250/month to your SMUD bill.

Separate SMUD Meter (Duplex Meter Panel)

SMUD recommends a duplex meter installation for most ADU situations. This replaces your existing single-meter panel with a dual-meter panel, giving the ADU its own SMUD account and monthly bill. Best for: long-term rental ADUs.

Costs: SMUD itself does not charge a connection fee for the second meter. However, the electrical work — duplex meter panel, trenching, and switchover — typically runs $3,000–$8,000. If your service also needs an amperage upgrade, expect $8,000–$15,000 total.

The critical SMUD timeline: SMUD’s typical process from application to occupancy takes four to six months, and ADU projects frequently exceed that. Their handout recommends planning at least six months in advance. The process includes a free consultation, site evaluation, engineering review, panel location approval, and final meter set after inspections pass.

Key details from SMUD’s ADU process: – Meters are typically grouped on the primary dwelling — not on the ADU itself – Check for overhead power line conflicts early — relocation adds $2,000–$5,000 – SMUD energizes service only after both SMUD and city inspection approvals are complete – Start your SMUD application the same week you submit your building permit

Our recommendation: If you’re building a rental ADU, invest in the separate meter. The upfront cost pays for itself within 1–2 years through tenant-paid utilities. Sacramento ADU rents typically range from $1,500–$2,500/month, and absorbing utility costs on hot-summer months is a financial liability you don’t need.

3. Minimum Circuit Requirements for Kitchens, Bathrooms, HVAC, and General Use

An ADU isn’t a shed with an extension cord. Because it’s classified as a dwelling unit under the California Residential Code, it must meet the same circuit standards as a full-size house. The National Electrical Code (NEC) and California Electrical Code (CEC) dictate exactly what’s required, and Sacramento inspectors enforce these to the letter.

Kitchen Circuits (40–50 Amps Total)

• Two dedicated 20-amp small appliance circuits for countertop receptacles (NEC 210.11(C)(1))
• Dedicated 40–50 amp, 240-volt circuit for the range/oven (or induction cooktop — increasingly common in all-electric Sacramento ADUs)
• Dedicated circuits for the dishwasher (20A), refrigerator (20A), and garbage disposal/microwave

Bathroom Circuits

• One dedicated 20-amp GFCI-protected circuit per bathroom — cannot extend to other rooms

HVAC Circuits (30–60 Amps)

• Dedicated circuit for the mini-split heat pump — typically 20–40 amp, 240-volt depending on BTU rating
• Dedicated 30-amp, 240-volt circuit for the water heater (heat pump water heaters are increasingly required under Title 24)

Sacramento climate note: Don’t undersize your HVAC circuit. Our summers regularly hit 100°F+ and winter lows drop into the 30s. Size the circuit one step above the manufacturer’s minimum spec.

Laundry and General Circuits

• 20-amp washer circuit and 30-amp, 240-volt dryer circuit — even if you’re not installing laundry on day one, California code requires the wiring to be in place
• 15-amp or 20-amp general-purpose circuits for living areas and bedrooms
• AFCI protection required in bedrooms and living rooms; GFCI protection in kitchens, baths, laundry, and exterior outlets
• Outlet spacing: no more than 12 feet apart along walls; within 6 feet of any doorway
• EV charger readiness: conduit from the subpanel to a future charger location is now code-required. Adding a live 240-volt outlet during construction costs $800–$1,500 — far less than retrofitting later.

Total circuit count for a typical 1-bedroom Sacramento ADU: 12–16 circuits. A 2-bedroom unit with full kitchen and laundry: 16–20 circuits.

4. Title 24 Energy Compliance for New Sacramento ADUs

Title 24, Part 6 — California’s Building Energy Efficiency Standards — applies to every new ADU in Sacramento. The 2025 Energy Code took effect January 1, 2026, and brings tighter requirements that directly affect your electrical design.

High-Efficacy Lighting

Every fixture must use LED lighting. Recessed fixtures must be IC-rated and fully enclosed — no screw-in lamp bases in recessed cans. Budget $500–$1,500 for all lighting fixtures in a typical ADU.

Solar PV System

New detached ADUs generally must include a solar PV system sized by state formulas for Sacramento’s CEC Climate Zone 12. Key exemption: if the calculated system falls below ~1.8 kW, the ADU may be exempt. This often applies to units under 500–600 sq ft. Garage conversions are also typically exempt. A small ADU solar system runs $4,000–$8,000 before the 30% federal tax credit.

Energy Storage System (ESS) Ready

Your ADU must be battery storage-ready, even without installing a battery on day one: – Minimum 60 amps of backed-up capacity – At least four identified ESS branch circuits (refrigerator, entry lighting, bedroom outlet, plus one additional) – Panel equipment capable of supporting future battery integration

With Sacramento’s increasing wildfire seasons and occasional PSPS events, ESS-ready wiring means you can add a backup battery later without rewiring your panel.

Electric-Ready Infrastructure

New ADUs must include conduit pathways from the panel to the water heater location and a designated EV charging location, plus panel capacity for future gas-to-electric conversion.

Pro tip: Going all-electric from the start (heat pump HVAC, heat pump water heater, induction cooktop) simplifies Title 24 compliance dramatically, avoids gas line extensions, and future-proofs the unit. Most ADUs we wire in Sacramento today are designed all-electric for these reasons.

Your plans must also include a Title 24 energy compliance report (CF-1R) from a certified consultant — typically $300–$800 in Sacramento.

5. Permit and Inspection Process for Sacramento County ADU Electrical Work

Every electrical circuit, panel, and connection must be permitted and inspected — whether through the City of Sacramento Community Development Department or the Sacramento County Building Permits & Inspection Division.

The Process Step by Step

1. Submit your ADU building permit application with architectural drawings, structural engineering, Title 24 report, and electrical plans. The City of Sacramento offers pre-approved ADU plan sets that can compress initial review to 1–3 weeks.
2. Pull an electrical sub-permit — typically $400–$1,200 depending on scope, pulled by your licensed C-10 electrical contractor.
3. Plan check and corrections — expect 2–3 rounds, each taking 2–4 weeks. Common electrical corrections: panel sizing documentation, load calculations, GFCI/AFCI specifications, and Title 24 lighting compliance.
4. Permit issuance — once corrections are cleared and fees paid.
5. Inspections during construction:
   • Underground/trenching inspection — before backfilling conduit runs
   • Rough electrical — all wiring, boxes, and conduit verified before drywall
   • Final electrical — devices, fixtures, panel, GFCI testing, breaker labeling confirmed
6. SMUD final and meter set — after city inspection passes
7. Certificate of Occupancy — your ADU is now legally habitable and rentable

Timeline and Costs

Phase	Typical Timeline
Design & engineering	4–8 weeks
Permit submittal & plan check	60–90 days
Corrections & resubmittal	4–8 weeks
SMUD coordination (separate meter)	4–6 months
Construction	4–7 months (detached)

Total permit fees in Sacramento: $4,500–$12,000. State law waives most impact fees for ADUs under 750 square feet.

What Catches People Off Guard

• Starting SMUD coordination too late — the #1 electrical delay on Sacramento ADU projects. Start your SMUD application the same week you submit permits.
• Existing panel surprises — older Sacramento homes often have Federal Pacific, Zinsco, or early Challenger panels that need complete replacement, not just an upgrade.
• Overhead line conflicts — SMUD’s ADU handout recommends checking for overhead power line conflicts during your initial site evaluation.

Frequently Asked Questions

How much does it cost to wire an ADU in Sacramento?

ADU electrical costs in the Sacramento area typically range from $4,000 to $15,000+, depending on whether you need a main panel upgrade, the trenching distance to a detached unit, and whether you’re installing a separate SMUD meter. A basic subpanel installation with short trenching runs on the lower end, while a full 400-amp service upgrade with duplex metering lands on the higher end.

Do I need a separate electrical meter for my Sacramento ADU?

No — California state law (SB-13) prohibits requiring separate utility meters for ADUs. However, SMUD recommends a duplex meter setup for most ADU situations, and installing a separate meter is strongly advisable for rental ADUs so tenants pay their own electricity. SMUD does not charge a connection fee for the second meter, but the electrical installation work typically costs $3,000–$8,000.

Can my existing 100-amp panel support an ADU without an upgrade?

In most cases, no. A licensed electrician must perform a load calculation, but if your 100-amp panel is already carrying 70–80 amps for the main house (common in older Sacramento homes), there isn’t enough headroom to safely feed a subpanel to the ADU. Upgrading to a 200-amp service is the typical solution and usually runs $2,500–$6,000 including the panel and SMUD coordination.

Ready to Get Started?

Building an ADU is one of the smartest investments a Sacramento homeowner can make — but the electrical work is the backbone of the project. From sizing the right subpanel and coordinating with SMUD to meeting Title 24 requirements and passing every inspection, getting it right the first time saves you from costly rework and months of delays. An experienced ADU electrician in Sacramento knows the local codes, SMUD processes, and inspection expectations that make the difference between a smooth build and a frustrating one.

Call TNT Electric today at (916) XXX-XXXX or schedule your free estimate to discuss your ADU electrical planning needs. We’ll start with a free load calculation and site evaluation so you know exactly what your project requires — before a single permit is filed.

TNT Electric Co. is Sacramento’s trusted licensed electrical contractor serving Sacramento, Roseville, Citrus Heights, Fair Oaks, Carmichael, and surrounding areas.