Can I run power to my ADU overhead instead of underground?

Sometimes. The electrical code allows an overhead feeder from the main house to a detached ADU on the same lot if the conductors are rated for the use, properly supported and kept at the required clearances above grade, driveways and roofs and away from windows, doors and decks. Whether it is practical depends on your site, your local rules and, if the ADU will have its own meter, your utility's service standards.

What Article 225 requires for an overhead feeder

• Height above ground. Minimum clearances apply above finished grade and walkways, with greater clearances over residential driveways and more again over public streets and areas with truck traffic.
• Clearance over roofs. Conductors crossing a roof need vertical clearance above it, with reduced distances allowed only in limited cases such as steep roofs or short runs over an overhang.
• Clearance from openings. Conductors must stay clear of windows that open, doors, porches, balconies, stairs and similar places people can reach, and can't run beneath openings that materials pass through.
• Support and attachment. The attachment point on each building must be high enough to hold those clearances across the whole span, and strong enough to carry it.
• Disconnect at the ADU. As with an underground feeder, the ADU needs a disconnect at a readily accessible location nearest where the conductors enter.

If the ADU gets its own utility service

Utilities write their own rules for overhead service drops. LADWP's service requirements, for example, call for a single service point per lot and, unless the utility approves otherwise, all meters grouped at one location on the primary residence. Its overhead options include using the existing meter, a two-position meter panel with a single service head, or two meter panels with separate service heads grouped together. Power still has to get from those grouped meters to the ADU, typically on a customer-owned feeder.

Why many owners still choose underground

• A span across the yard can conflict with trees, a future second story, a pergola or the ADU's own roof eaves.
• Required heights can call for a tall mast on the ADU, which affects appearance and design review.
• Underground conduit is out of sight and out of the way of future yard projects once it's in.

On the other hand, overhead can make sense where a trench would cut through mature tree roots, a long run of hardscape or a septic area.

What this means for your electrical plan

For an overhead feeder, the plan should show the route, attachment points and heights, clearances at roofs, windows and driveways, the conductor type, and the mast or support detail. For underground, it shows the trench and conduit instead. Compare the options in how a detached ADU subpanel works, check your yard limits in ADU setback requirements, and start utility coordination early if a new service is involved.

Sources: ecmweb.com, webprod.ladwp.com, dgs.ca.gov.