Okay, Dustin. This is a common point of contention, and the inspector is likely correct, depending on the specifics of your installation and local amendments. Here's a breakdown of the issue and relevant NEC codes

The Inspector's Reasoning & Why It's Likely Correct

The inspector is likely citing code sections that emphasize the feeder's protection and the fact that effectively you have a separate building being fed through the main dwelling. Even though the ADU is technically a dwelling unit on the same property, it’s treated more like a separate building when it comes to feeders.Here’s the logic and NEC code sections that support the inspector's position: Protection of Feeders

The NEC generally requires that feeders be protected from physical damage. SER cable is surface rated, and therefore cannot be ran in conduit.

Separate Structure Considerations

While an ADU might be attached, the code often treats it as a separate structure when it comes to feeder wiring. This is because it's a distinct living unit with its own electrical needs.

2023 NEC 334.12 (A)(10)

Uses not permittedThis section specifically states that:Romex (NM cable, NMS, & NMC) is not permitted to be installed in the following locations:(10) Where exposed to physical damage

2023 NEC 300.3 (C)(1)

Single Conductors.Single conductors shall only be permitted to be installed where any of the following apply:(1) Part of a complete cable assemblyThis means, you cannot remove each conductor from your SE cable to place into separate conduits.

2023 NEC 338.10 (B)(4)(a)

Through interior of dwelling unit. Service-entrance cable shall be permitted to pass through the interior of a dwelling unit, provided it is installed in accordance with all of the following:(1) The cable is installed in accordance with the requirements of Article 334.

Why Multi-Family Apartments Are Different

You mentioned multi-family apartments. There's a key distinction here: Ownership and Management

In a multi-family apartment building, there's usually a single owner or management company responsible for the entire building. The wiring within the building is under the control of that single entity.

Defined Fire Barriers

Apartment buildings are often designed with specific fire-rated walls and floors that act as barriers. The wiring within those fire-rated assemblies is treated differently.

Accessibility for Maintenance

The main electrical distribution for an apartment building is typically accessible to building maintenance personnel.In your ADU scenario, you effectively have two separate dwelling units with potentially different occupants. If a fault occurs in the feeder to the ADU, the occupants of the main house might not be able to easily access or control the situation.

What You Need to Do

Here are your likely options to satisfy the inspector:1. Reroute the Feeder Outside

This is often the best solution. Run the feeder outside the main house. You can bury it in conduit underground (using the appropriate type of conduit for underground burial and direct burial-rated conductors like USE), or run it on the exterior of the house in rigid metal conduit (RMC) or intermediate metal conduit (IMC). If running outside on the house, consider how it looks and if it’s susceptible to physical damage.2.

Use a Different Wiring Method Inside

Instead of SER cable, use individual conductors in conduit (EMT or PVC, depending on location and local codes) for the section that passes through the house. This allows you to use the conduit for protection and meet the code requirements.3.

Talk to the Inspector

Nicely explain your situation and ask for clarification. The inspector might have a specific concern that you can address with a slightly different approach. Sometimes, adding additional physical protection to the SER cable (e.g., running it through a short section of conduit where it's most vulnerable) can satisfy the inspector, but don’t count on it.4.

Appeal the Ruling

If you strongly believe the inspector is incorrect, you have the right to appeal the ruling. This usually involves submitting documentation and presenting your case to a higher authority within the building department. However, be sure you have a solid legal basis for your appeal.

Important Considerations



Local Amendments

San Diego, CA may have specific local amendments to the NEC that are more stringent. Always check with the local building department for any local variations.

Professional Opinion

This is a tricky area. Consult with a licensed electrical engineer or a master electrician with experience in ADU installations in your area. They can provide specific advice based on your situation.

In Summary

The inspector is most likely correct based on the NEC and the need to protect feeders supplying a separate dwelling unit (the ADU) from physical damage. Your best bet is to reroute the feeder outside the main house or use a different wiring method that provides adequate protection (conduit). Talk to the inspector to understand their specific concerns and explore possible solutions.

Disclaimer: I am an AI chatbot and cannot provide professional electrical advice. Always consult with a licensed electrician for any electrical work. Flag for review