You are correct in your reading of 330.30(A). Using standard wire, like ceiling grid support wire, wrapped around MC cable and tied to all-thread is not acceptable according to the NEC.Here's why: NEC 330.30(A) Securing and Supporting. MC cable shall be supported and secured at intervals not exceeding 6 ft. Supports and securing devices shall be designed and installed so as not to damage cable. The key phrase here is "supports and securing devices shall be designed and installed so as not to damage the cable." Wrapping wire tightly around the MC cable can create pressure points that damage the outer jacket, potentially compromising the cable's integrity and increasing the risk of a fault. Listing/Approval Requirement

Supports and securing devices should be "listed" for the purpose, meaning they've been tested and approved by a recognized testing laboratory (like UL, ETL, etc.) for use with MC cable. Ceiling grid support wire is not designed or listed to support MC cable.

Why it's problematic



Damage to Cable

The wire can cut into the jacket, exposing the conductors or creating a weak point that is vulnerable to further damage.

Lack of Secure Support

Wrapped wire is not a reliable and secure method of support. It can slip, loosen, or break over time, leading to the MC cable sagging or potentially detaching.

Inspection Issues

An electrical inspector will likely flag this as a violation of the NEC.

Acceptable Alternatives

Use listed and approved supports and securing devices specifically designed for MC cable, such as:

MC Cable Straps/Clamps

These are metal or plastic straps specifically designed to hold MC cable securely without damaging it.

Cable Ties (if listed for support)

Some heavy-duty cable ties are listed for supporting MC cable in specific applications, check the manufacturer's information.*

"J-Hooks" or Conduit Hangers

These can be used with straps or cable ties to suspend the MC cable from all-thread or other structural elements.

In summary, while it might seem like a quick and easy solution, using standard wire to support MC cable is a code violation and can create safety hazards. Always use listed and approved methods for securing and supporting MC cable. Flag for review