9 Must-Have Electrical Upgrades for Your Sacramento ADU or Granny Flat

Sacramento’s ADU boom shows no signs of slowing down. Since California passed AB 68 and SB 13 streamlining accessory dwelling unit permits, Sacramento County has seen thousands of new ADU applications—and that number keeps climbing. Whether you’re building a backyard granny flat for aging parents, creating a rental unit to offset your mortgage, or adding a detached home office in Land Park or Elk Grove, the electrical system is the backbone that makes your ADU safe, comfortable, and code-compliant.

Here’s the problem: many homeowners focus on finishes and floor plans while treating electrical as an afterthought. That’s how you end up with a failed inspection, costly rework, or a unit that can’t handle a tenant running the microwave and air conditioner at the same time. Our team at TNT Electric has wired hundreds of ADUs across the Sacramento region, and we’ve learned exactly what separates a trouble-free build from a frustrating one.

Below are the 9 electrical upgrades every Sacramento ADU needs—with real cost ranges, local code details, and insider tips from our licensed electricians.

Separate Sub-Panel (or New Service)
Dedicated Kitchen Circuits
GFCI Protection in All Wet Areas
A Proper Lighting Plan
EV-Ready Outlet in Garage or Carport
Dedicated Mini-Split HVAC Circuit
Interconnected Smoke and CO Detectors
Outdoor and Pathway Lighting
Smart Home Pre-Wiring

1. Separate Sub-Panel (or New Service)

Every ADU needs its own electrical distribution, and this is the single most important decision in your entire ADU electrical plan. Sacramento County and the California Electrical Code require that your accessory dwelling unit has an adequate, dedicated power supply—and in most cases, that means installing a separate sub-panel fed from your main house panel or, for larger units, an entirely new electrical service from SMUD.

For a typical 400–750 sq. ft. ADU, a 60-amp to 100-amp sub-panel handles the load comfortably. If you’re building a larger unit with electric heating, an EV charger, and a full kitchen, you may need 125 amps or more. Our team often recommends oversizing the sub-panel slightly—adding a few extra breaker spaces now costs a fraction of what a panel swap costs later.

Here’s what most homeowners don’t realize: your existing main panel needs enough spare capacity to feed the new sub-panel. Many Sacramento homes built in the 1970s and 1980s—common in Arden-Arcade, Carmichael, and Rancho Cordova—still have 100-amp or even 60-amp main panels. If that’s your situation, you’ll likely need a main panel upgrade before your ADU work can begin. SMUD will need to approve the increased service, and there’s a lead time for that, so plan early.

Cost range: $1,800–$4,500 for a sub-panel installation; $3,500–$7,000+ if a main panel upgrade is also required.

Pro tip: Submit your SMUD service request as soon as your ADU plans are approved. SMUD’s queue for new service connections in the Sacramento metro area can run 4–8 weeks, and delays here stall your entire project timeline.

2. Dedicated Kitchen Circuits

If your ADU includes a kitchen or kitchenette—and most do, since that’s what makes it a truly independent living space—the National Electrical Code (NEC) requires multiple dedicated circuits to handle the electrical load safely. This isn’t optional; it’s code, and Sacramento building inspectors check it closely.

At minimum, your ADU kitchen needs:

Two 20-amp small appliance branch circuits for countertop receptacles (NEC 210.11(C)(1))
One dedicated 20-amp circuit for the dishwasher
One dedicated 20-amp circuit for the refrigerator (recommended, though not always code-required)
One dedicated circuit for the microwave/range hood, typically 20 amps
A 40-amp or 50-amp circuit for an electric range, if applicable

That’s a minimum of five to six circuits just for the kitchen in a unit that might only be 500 square feet. Skimping here is the fastest way to trip breakers constantly—imagine your future tenant running a coffee maker, toaster, and microwave on the same circuit every morning.

For ADUs with electric cooking (increasingly common as Sacramento moves toward all-electric new construction under Title 24’s 2022 Energy Code), you’ll also want to think about load calculations carefully. Our team runs a full NEC Article 220 load calculation for every ADU we wire to make sure the sub-panel can handle peak demand.

Cost range: $1,200–$2,800 for all dedicated kitchen circuits, depending on unit layout and panel distance.

Pro tip: Even if you’re installing a kitchenette with just a microwave and mini-fridge now, rough in wiring for a full kitchen. It’s a small upfront investment that dramatically increases your ADU’s flexibility and resale value.

3. GFCI Protection in All Wet Areas

Ground-fault circuit interrupter (GFCI) protection is non-negotiable in any ADU, and the NEC’s requirements have expanded significantly in recent code cycles. Every outlet within six feet of a water source—kitchen sinks, bathroom sinks, laundry areas—needs GFCI protection. But the current code goes further than many homeowners expect.

For your Sacramento ADU, GFCI protection is required in:

All kitchen receptacles serving countertop surfaces
Bathrooms — every single receptacle
Laundry areas (washer receptacle included)
Garages and accessory buildings
Outdoor receptacles — all of them, no exceptions
Unfinished basements and crawl spaces (if your ADU design includes these)

The 2023 NEC (which California is adopting) also expands GFCI requirements to cover all 240-volt outlets in certain locations, including EV charger circuits in garages. Sacramento inspectors are increasingly enforcing these updated requirements on new ADU construction.

We install GFCI breakers at the panel rather than individual GFCI outlets in most ADU projects. This approach protects the entire circuit, simplifies troubleshooting, and gives the unit a cleaner look with standard-style receptacles throughout. It’s slightly more expensive upfront but saves headaches over the life of the unit.

Cost range: $300–$800 total for comprehensive GFCI protection, depending on the number of circuits.

Pro tip: Test every GFCI device monthly by pressing the “Test” button. Include a brief guide for your tenants—many renters don’t know what a GFCI is or how to reset a tripped outlet, which leads to unnecessary service calls.

4. A Proper Lighting Plan (Not Just Can Lights Everywhere)

Lighting makes or breaks a small space, and ADUs are almost always compact. A thoughtful lighting plan is one of the most cost-effective ADU electrical upgrades you can make—it transforms a cramped-feeling 500-square-foot unit into something that feels open and inviting.

Here’s what we recommend for Sacramento ADUs:

Layered lighting in the main living area: a combination of recessed cans for ambient light, under-cabinet or cove lighting for task areas, and at least one switched outlet for a floor or table lamp.
High-efficacy LED fixtures throughout — California’s Title 24 Energy Code requires this for all new construction, and Sacramento inspectors verify compliance. Every permanently installed fixture must be high-efficacy (essentially LED).
Dimmer switches in the living room and bedroom. They’re inexpensive, reduce energy use, and tenants love them.
Adequate bathroom lighting — a vanity light bar above or flanking the mirror, plus a ceiling fixture. Don’t rely on a single overhead light; it creates harsh shadows.
Kitchen task lighting — recessed cans or track lighting above counters, plus under-cabinet LED strips for food prep areas.

Sacramento’s intense summer sunlight also creates unique lighting considerations. South- and west-facing ADUs in neighborhoods like East Sacramento and Curtis Park get flooded with afternoon light from May through October. Design your lighting plan around natural light patterns so the unit doesn’t feel over-lit during the day or cave-like at night.

Cost range: $1,500–$3,500 for a complete ADU lighting package including fixtures, switches, and dimmers.

Pro tip: Wire at least two lighting circuits in your ADU—one for general/living areas and one for kitchen/bath. This way, a tripped breaker doesn’t plunge the entire unit into darkness.

5. EV-Ready Outlet in Garage or Carport

California’s CALGreen building code now requires EV-ready infrastructure in new construction, and that includes ADUs with dedicated parking. Even if your tenant doesn’t drive an electric vehicle today, this is one of the smartest future-proofing investments you can make.

Being “EV-ready” means installing a dedicated 240-volt, 50-amp circuit from the sub-panel to the parking area, terminated with a NEMA 14-50 receptacle. This outlet can charge most Level 2 EV chargers, adding roughly 25–30 miles of range per hour—more than enough to fully charge a typical EV overnight.

In the Sacramento market, EV-readiness is a genuine differentiator for rental ADUs. With SMUD’s favorable time-of-use electricity rates (charging overnight costs a fraction of daytime rates) and the growing number of EV drivers in the region, a ready-to-go charging outlet can justify higher rent and attract a wider pool of tenants.

If your ADU doesn’t include a garage or carport, consider running the circuit to a weatherproof NEMA 14-50 outlet on an exterior wall near the designated parking spot. Make sure it’s on its own breaker and protected by a GFCI breaker per the latest code requirements.

Cost range: $800–$2,000 for a dedicated 240V/50A circuit and outlet, depending on distance from the panel.

Pro tip: Check SMUD’s current EV charger rebate programs before your install. SMUD has historically offered $50–$599 rebates for residential EV charger installations, which can offset a significant chunk of the wiring cost.

6. Dedicated Mini-Split HVAC Circuit

Sacramento summers regularly hit 100°F or higher, and winters dip into the 30s. Your ADU absolutely needs its own climate control, and a ductless mini-split heat pump is the go-to choice for most ADU builds in our area. They’re efficient, compact, provide both heating and cooling, and—critically—they satisfy Title 24 energy requirements more easily than most alternatives.

From an electrical standpoint, a mini-split needs a dedicated 240-volt circuit, typically 20–30 amps depending on the unit’s BTU capacity. A single-zone mini-split sized for a 500–750 sq. ft. ADU (typically 12,000–18,000 BTU) usually requires a 20-amp, 240V circuit with a disconnect box mounted on the exterior wall near the outdoor condenser unit. That disconnect is code-required and must be within sight of the unit.

Why this matters for your sub-panel sizing: The mini-split circuit is one of the largest loads in your ADU. If you’re also running an electric range and an EV charger, your electrical load adds up fast. This is exactly why we emphasize proper load calculations during the planning phase—undersizing the sub-panel to save $500 now can cost $5,000 in rework later.

Our team coordinates directly with HVAC installers on every ADU project to make sure the electrical rough-in matches the exact mini-split model being installed. Different manufacturers have different wiring requirements, and mismatches cause inspection delays.

Cost range: $500–$1,200 for the dedicated circuit, disconnect, and wiring (electrical only; the mini-split unit and HVAC install are separate).

Pro tip: Install the disconnect box on the same wall as the condenser unit, within arm’s reach. Inspectors will fail it if it’s more than 50 feet away or not within line of sight. Get the mini-split model number from your HVAC contractor before the electrical rough-in to avoid re-work.

7. Interconnected Smoke and CO Detectors

This one isn’t glamorous, but it’s life safety—and California has specific requirements that go beyond what many homeowners expect. For ADUs, Sacramento building code requires hardwired, interconnected smoke alarms in every bedroom, outside each sleeping area, and on every level of the unit. If your ADU has any gas appliances (water heater, furnace, stove), you also need carbon monoxide detectors outside sleeping areas.

“Interconnected” means that when one alarm triggers, all alarms in the ADU sound simultaneously. This is a California requirement (California Health & Safety Code Section 13113.7) and it must be achieved through hardwiring or listed wireless interconnection—battery-only detectors don’t satisfy code for new construction.

For a typical one-bedroom ADU, plan on:

1–2 smoke detectors in the bedroom and hallway
1 smoke detector in the living/main area
1 combination smoke/CO detector near the sleeping area (if gas appliances are present)
All units wired on a shared signal wire for interconnection

We prefer combination smoke/CO units with sealed 10-year lithium batteries as backup. They reduce the number of devices on the ceiling and simplify maintenance for tenants.

Cost range: $400–$900 for supply and installation of all required hardwired detectors in a typical ADU.

Pro tip: Include the smoke/CO detector circuit in your rough-in wiring before drywall goes up. Adding interconnected hardwired detectors after the walls are finished requires cutting, patching, and repainting—tripling the labor cost.

8. Outdoor and Pathway Lighting

Your ADU isn’t just the interior—the path between the main house and the ADU needs safe, code-compliant lighting too. Sacramento building code requires illumination for walkways, stairs, and entries, and a well-lit path also reduces your liability as a property owner.

At minimum, plan for:

A porch light or wall sconce at the ADU entry door (on a switch inside the unit)
Pathway lights along the walkway from the main house to the ADU—typically low-voltage LED path lights or bollard-style fixtures
A motion-activated security light covering the parking area or side yard
Address lighting if the ADU has a separate address (required in Sacramento for units with independent addresses for emergency response)

Low-voltage landscape lighting (12V) is the most popular choice for pathway illumination in Sacramento ADU projects. It’s safe, energy-efficient, and doesn’t require conduit—making it far less expensive to install than line-voltage alternatives. We install a dedicated low-voltage transformer connected to an outdoor-rated GFCI outlet, giving you a clean, expandable system.

For neighborhoods with mature tree canopies—like those in midtown Sacramento, Tahoe Park, and the Fab 40s—motion-sensor lighting is especially important. Dense landscaping creates dark spots that overhead street lights can’t reach.

Cost range: $600–$2,000 for a complete outdoor lighting package, depending on pathway length and fixture quality.

Pro tip: Put outdoor lights on a photocell or astronomical timer so they turn on automatically at dusk. Tenants won’t remember to flip a switch, and a dark path is a slip-and-fall claim waiting to happen.

9. Smart Home Pre-Wiring

You don’t need to install a full smart home system in your ADU, but pre-wiring for one is inexpensive during construction and nearly impossible to add later without opening walls. This is the kind of future-proofing that costs a few hundred dollars now and adds thousands in value and appeal down the road.

At minimum, we recommend pre-wiring for:

A structured media panel (small enclosure in a closet) with Cat6 Ethernet runs to the living room and bedroom
A dedicated circuit for a Wi-Fi access point — essential for tenants who need reliable internet, especially if the ADU is at the back of the lot and far from the main house’s router
Smart switch-compatible wiring — this means running a neutral wire to every switch box (required by most smart switches and dimmers, and already required by current NEC code for new construction)
A video doorbell circuit — low-voltage wiring and a transformer at the front door
Pre-wired locations for smart locks, security cameras, or a smart thermostat

In the Sacramento rental market, strong internet connectivity is a top tenant priority. A hardwired Ethernet connection and a dedicated access point eliminate the “my Wi-Fi doesn’t reach the back unit” complaint that plagues so many ADU landlords. It’s especially relevant for ADUs in deep lots, which are common in Pocket, South Land Park, and College Greens where homes often sit 80–120 feet from the street.

Cost range: $500–$1,500 for basic smart home pre-wiring during new construction.

Pro tip: Run at least two Cat6 cables and one RG6 coax cable to the media panel location, even if you don’t plan to use them all immediately. Pulling cable through open walls takes 15 minutes; fishing it through finished walls takes hours.

Frequently Asked Questions

Does my Sacramento ADU need its own electrical meter?

It depends on your setup and goals. Sacramento City Code doesn’t always require a separate meter for ADUs, but SMUD offers the option of a separate meter which can be advantageous if your tenant pays their own electricity. A separate meter also makes it easier to qualify for SMUD’s lower baseline rates on both the main house and ADU. Talk to SMUD and your electrician early in the design phase to weigh the costs versus benefits—adding a meter later is significantly more expensive than doing it during initial construction.

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

The total electrical cost for a typical 400–750 sq. ft. Sacramento ADU ranges from $8,000 to $20,000, depending on the unit’s size, appliance choices (gas vs. all-electric), and how much work is needed on the main house panel. That includes the sub-panel, all circuits, fixtures, devices, and inspection. All-electric ADUs with EV charging and smart home pre-wiring land on the higher end. We provide detailed, itemized estimates after reviewing your plans so there are no surprises.

What ADU electrical requirements does Sacramento have that are different from the rest of California?

Sacramento follows the California Electrical Code (based on the NEC) plus local amendments enforced by the Sacramento City or County building department, depending on your jurisdiction. Key local factors include SMUD’s specific service connection requirements (which differ from PG&E areas), Sacramento’s aggressive push toward all-electric new construction, and Title 24 energy compliance—which your electrician must document and the inspector will verify. Additionally, Sacramento’s extreme heat means load calculations for cooling are critical; an undersized electrical system that works fine in a coastal ADU won’t cut it when it’s 108°F in July.

Ready to Get Started?

Building an ADU is one of the smartest investments Sacramento homeowners can make—but only if the electrical system is done right from day one. From sizing your sub-panel to pre-wiring for smart home technology, every decision you make during the planning phase affects your ADU’s safety, comfort, and long-term value.

The nine upgrades above aren’t extras or luxuries. They’re the electrical foundation that makes your ADU code-compliant, efficient, and genuinely livable. Skip any of them, and you risk failed inspections, costly rework, or a finished unit that frustrates you and your tenants for years.

At TNT Electric, we specialize in ADU electrical services across the Sacramento metro area. Our licensed electricians have wired ADUs in every configuration—garage conversions, detached new builds, additions above existing structures—and we work directly with your general contractor and SMUD to keep your project on schedule.

Call TNT Electric today at (916) XXX-XXXX or schedule your free ADU electrical consultation to discuss your ADU electrical needs.

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