What Is a Separate Utility Meter for an ADU?

Key takeaways

• A separate meter means the utility bills the ADU on its own account.
• A shared meter means one bill for the house and the ADU together.
• A submeter is your own meter, behind the utility's, that measures the ADU's share.
• In California, cities and water agencies cannot demand a separate connection for some ADUs built inside an existing home or structure ¹.
• Electric utilities follow their own filed rules. PG&E's rule meters each dwelling unit, with exceptions ³.
• If you rent with a shared gas or power meter, California law says you must tell the tenant and agree in writing ⁴.
• Ask the utility early. Its answer can change your electrical design and budget.

What a separate meter means, in plain English

A meter is the box that counts how much power, gas or water you use. The utility reads it and sends a bill.

With a separate meter, the ADU gets its own box and its own bill. The person living there can open their own account.

With a shared meter, the main house and the ADU use one box. You get one bill and work out the split yourself.

A submeter sits further down the line, on your side of the utility meter. The diagram traces that path for power, from the street to the ADU.

Why it matters to you

The meter choice shapes three things: how much the hookup costs, how you bill a tenant, and whether your house service can carry the extra load.

A separate meter often means a new service line, new equipment and digging. A shared meter avoids that, but may push your existing panel to its limit. The ADU electrical panel page explains that load question.

It also matters for renting. A shared meter means you must agree with the tenant on the split. A separate meter makes that simple.

Separate, shared or submetered

How getting a separate meter works

Each utility has its own process. These are the usual stages.

1. Your designer or electrician works out the ADU's electrical load.
2. You apply to the utility for new service, with a site plan and load details.
3. The utility decides where the service will come from and what it needs from you.
4. Your contractor does the site work, such as trenching and conduit, to the utility's specs.
5. The city inspects the electrical work under your building permit.
6. The utility sets the meter and opens an account.

Water and sewer are separate requests to the water or sewer agency, under their own rules.

Two California rules that point different ways

State law limits who may demand a separate connection. Under Gov. Code § 66311.5(d), for an ADU or JADU created within an existing or proposed single-family home or accessory structure under § 66323(a)(1), a local agency, special district or water corporation may not require a new or separate utility connection directly between the unit and the utility.

It also may not charge a related connection fee or capacity charge. The exceptions are a unit built with a new single-family home, or one conveyed (sold) separately ¹.

The section was numbered 66324 until SB 543 (Stats. 2025, ch. 520) renumbered it from 1 January 2026.

For other ADUs, such as many new detached units, § 66311.5(e) lets them require one.

Any connection fee or capacity charge must be proportionate to the ADU's burden on the system, based on its square feet or its drainage fixture units (a plumbing measure of how much wastewater fixtures send), and must not exceed the reasonable cost of the service ¹.

Electric utilities are regulated by the CPUC (California Public Utilities Commission) through filed tariffs, which are their official rulebooks.

PG&E's Electric Rule 18, section C.1, says PG&E "will furnish and meter electricity to each individual residential dwelling unit", with listed exceptions ³.

The same rule says junior ADUs are not residential dwelling units for this purpose and need not be metered separately, citing Gov. Code § 66338 ².

How these interact on your ADU, and whether your utility will serve it through the house meter, is decided by the utility and the permitting agency. Ask both before the electrical design is fixed. The utility connection research records the conflict as found.

Sources: [1] [3]

California: what each ADU type usually faces

Worked example: splitting a shared bill

A hypothetical shared electric bill, split three ways. The dollar amounts and usage are made up for arithmetic only. They are not typical bills.

In California, whichever method you pick, you must disclose the shared meter to the tenant and put the payment deal in writing ⁴. With a submeter, the rate you charge matters too; see the rules section.

Where you will see meter terms

• The utility's service application: new service, load and meter location.
• The electrical sheet of your permit set: service size, meter and panel layout.
• A builder's bid: a line for trenching, conduit or "utility coordination."
• A city or water agency letter: whether a separate connection and fee apply.
• The lease: who pays which utility, and the shared-meter agreement.

Rules: California first, then other places

Renting with a shared meter has its own California rule. If a tenant's gas or power meter also serves an area outside their unit, the landlord must disclose it before the tenancy starts, or once found.

The landlord must then agree in writing on who pays, or make another written arrangement, such as becoming the customer of record ⁴. A tenant can go to court if this is not done.

Submetering has limits too. California's Public Utilities Code § 739.5 says that when a master-meter customer supplies gas or power to tenants in an apartment building or similar residential complex, it must charge each tenant the same rate the utility would charge directly ⁵.

Whether that applies to a house with one ADU is a question for the utility or a lawyer. PG&E Rule 18 also limits reselling power to listed cases ³.

Outside California, each state's utility commission and each utility sets its own rules. See the ADU laws by state tracker and ask your utility.

Costs and what drives them

HyreADU does not give a price for a separate meter. Prices depend on the utility's tariff, your site and the contractor's bid, and we have no sourced dataset for them.

The main cost drivers are the distance from the utility's line to the meter, whether trenching crosses hard surfaces, whether the line runs overhead or underground, the size of the new service, and any utility fees.

For water and sewer, the agency's connection or capacity charge can add to it, within the § 66311.5 limits ¹.

For overall budgets, see ADU utility connection statistics and the ADU cost calculator.

A decision rule for owners

Once the utility has said what it will allow, these questions usually settle it.

• Renting long term? A separate meter lets the tenant carry the bill and avoids disputes over a split.
• Housing family, or a JADU? A shared meter is usually simplest and cheapest.
• House service already near capacity? A separate service may be the alternative to upgrading the house service; compare both.
• Planning to sell the ADU separately later? Separate conveyance is a trigger in § 66311.5(d), so plan for separate services.
• Thinking of a submeter to bill the tenant? Read the utility's resale and submetering rules first; PG&E Rule 18 restricts resale to listed cases.

Benefits and limits of a separate meter

Common mistakes and myths

Myth "State law says my ADU never needs a separate meter."

Reality The § 66311.5(d) limit covers some ADUs inside an existing home or structure, and binds local agencies and water companies. Electric metering follows the utility's tariff ^{1 3}.

Myth "A submeter lets me charge the tenant any rate."

Reality Utility tariffs and California law limit reselling power; for some properties the rate must match the utility's ^{5 3}.

Myth "A shared meter needs no paperwork."

Reality If you rent the unit, California requires disclosure and a written payment agreement ⁴.

Myth "I can decide the meter after the design is done."

Reality The utility's answer can change the panel, the trench and the budget. Ask first.

What to ask the utility and the city

• Electric utility: does my ADU type need its own meter under your rules?
• Electric utility: where would the new service come from, and what site work is mine?
• Electric utility: may I submeter the ADU and bill a tenant, and at what rate?
• Water and sewer agency: will you require a separate connection, and what fee applies under § 66311.5?
• City: does my approval path fall under § 66323(a)(1)?
• Both: how long does a new service usually take right now?

Checklist for your project

1. Confirm your ADU type and approval path.
2. Get a load calculation for the ADU and the house together.
3. Ask the utility in writing what it requires for your ADU.
4. Ask the water and sewer agency the same.
5. Compare the cost of a separate service with a house panel upgrade.
6. Pick separate, shared or submetered, and design to it.
7. If you will rent, write the utility terms into the lease, with the shared-meter disclosure if needed.

Where the meter decision sits

1. utility connection route
2. shared or separate service
3. ADU panel design
4. meter set by the utility
5. tenant or owner account

Outside California and outside PG&E territory

Related guides

• Renting an ADU
• ADU construction hub
• ADU ROI calculatorHow utility billing affects net rent
• Feasibility checker

Related terms

ADU Utility Connection

An ADU utility connection is the way an accessory dwelling unit gets water, sewer, electricity and, where used, gas: either as a branch off the main house's existing service, or as a new, separate connection running directly from the utility to the unit.

ADU Electrical Panel

An ADU electrical panel is the breaker panel that distributes power to the circuits inside an accessory dwelling unit, usually a subpanel fed from the main house panel, or a main panel on its own utility service and meter.

ADU Water Connection

An ADU water connection is the pipe that brings drinking water to an accessory dwelling unit, usually as a branch off the main house's water line, or as a new service with its own meter where the water provider requires or allows one.

Long-Term Rental ADU

A long-term rental ADU is an accessory dwelling unit leased to a tenant who lives in it as their home, usually for a month-to-month or fixed-term lease, rather than rented to short-stay guests.

Junior ADU

A junior ADU (JADU) is a small home of no more than 500 square feet carved out of an existing or proposed single-family house, with its own entrance and an efficiency kitchen, and permission to share the main home’s bathroom.

ADU Rental

Renting out an ADU, long-term to a tenant or, where local rules allow, short-term to guests.

Detached ADU

A detached ADU is an accessory dwelling unit built as its own freestanding building on the same lot as the main home, usually in the backyard, with its own kitchen, bathroom and entrance.

Also referenced from: ADU Utility Connection, ADU Water Connection, ADU Electrical Panel, ADU Rental Agreement, Long-Term Rental ADU