You're right to question the application of 330.15 in this scenario. Let's break it down: What 330.15 really means

The requirement to run "closely following the surface of the building finish" in 330.15 (and similar sections for other wiring methods) is intended to prevent long, unsupported runs of cable that could sag, be easily damaged, or create a safety hazard. It's about neat and workmanlike installation.

Interpretation and Practicality

The intent is not to force you to staple every few inches, gluing cable to the walls. In residential wiring like apartments, the practical application of 330.15 usually involves using supports that keep the cable run neat, secure, and reasonably close to the building surface.

The Photo & Interpretation

Your picture does appear to comply with 330.15 as long as the hangers you are using for support are installed at sufficient intervals to ensure the cable(s) are closely following the structure of the building.

Stacking Cables and Code

Stacking cables is generally permitted, but you need to be mindful of several factors:

Cable Type

The type of cable you're using is important. NM-B cable (Romex) is the most common type in residential work, and it's generally permitted to be bundled or stacked. However, check the specific cable manufacturer's specifications.

Bundle Size

Too many cables bundled together can create heat buildup, especially with higher current loads. Consider the ampacity of the cables and whether bundling might require derating. The NEC has rules for ampacity adjustment when multiple current-carrying conductors are bundled (see Article 310).

Secure Support

The support method must securely hold the stack of cables without damaging them. The hangers in your picture could work, but the installer needs to ensure the stack is firmly seated within the hanger and not putting undue stress on individual cables.

Neat and Workmanlike Manner (NEC 110.12)

This is a key principle. The installation must look professional, organized, and secure. A messy, haphazard stack of cables would likely be a code violation.

Alternatives and Considerations



Cable Trays

While less common in individual apartment units, cable trays are an excellent solution for running large numbers of cables in corridors or utility areas. If running a lot of communication cables (data/CATV), cable trays may be a good option.

J-Hooks/Bridle Rings

These are another common alternative to staples. They provide good support and allow for cable stacking.

Surface Raceways

For a more concealed and aesthetically pleasing installation, consider using surface-mounted raceways. These are especially useful in areas where exposed cables would be unsightly or vulnerable to damage.

Local AHJ (Authority Having Jurisdiction)

The most important* step is to confirm with your local electrical inspector (AHJ) what their interpretation of 330.15 is and what support methods they find acceptable for your specific situation. They have the final say on whether your installation complies with the code. A quick phone call or email can save you a lot of headaches later.

In summary, the photo could potentially comply with 330.15, so long as sufficient supports are used to ensure the cable(s) are close to the building structure.Key takeaway: Don't assume the worst. Talk to your local electrical inspector and get their guidance on the best way to run your cables while meeting code requirements and ensuring a safe and reliable installation. Flag for review