Does an ADU need its own separate electrical meter?

Usually no — most California ADUs are powered by a subpanel fed from the existing main house panel and share the main meter, which is the least expensive and fastest path. A separate meter (its own utility service) is only required in specific situations, and California law actually limits when utilities can force one. Whether you need one is partly a code/utility question and partly a billing preference.

When a separate meter is NOT required

If your existing service has spare capacity, a subpanel fed from the main panel is typically all you need. The ADU's electrical use is then billed together with the main house. California has generally restricted utilities from requiring a new, separate connection (and the associated connection fees) solely because an ADU is being added, so for many projects the shared-meter subpanel is both compliant and far less expensive.

When a separate service becomes necessary

• Insufficient main service capacity. If the load calculation shows the existing service can't carry both the house and the ADU even after a panel upgrade, a separate service may be the only viable route.
• Distance. When the ADU sits far from the main panel (often cited around 150 feet or more), a subpanel feeder becomes inefficient — heavy voltage drop forces large, expensive conductors — and a dedicated service can be cleaner.
• Utility or local policy. Some utilities or jurisdictions require separate metering under certain conditions. Policies differ by provider — verify with yours.

Separate billing — usually a choice, not a mandate

Many owners want a separate meter so a rental tenant pays their own electric bill. That's a legitimate goal, but weigh the trade-offs:

If you don't need separate billing, a private submeter is sometimes used to allocate costs without a full second utility service. A separate utility service involves its own meter socket, service-entrance conductors, utility engineering review, and inspections — a bigger lift you don't fully control, so decide early and submit the utility request in parallel with permitting.

Requirements vary by jurisdiction and utility — confirm with your local building department and serving utility.

Our electrical plans document whichever configuration applies, including the metering layout and the riser diagram. See the complete MEP guide for how subpanel versus separate-service decisions play out.