But that still doesn't answer my question.
What is the difference between "above" and "within" ceiling grid systems. If the two statements are equivalent, why does that code posted treat them differently. If they aren't, what is the difference?
Good question. I don't think the section quoted really comes from the National Electrical Code. I just grabbed my copy of the 2005 edition, which is what's in effect here. Article 90 is the first chapter, entitled "Introduction." It's about administration, not technical matters. And there is no section 90-13 -- it ends with section 90-9.
The NEC would never use terms like "City." It's written for use by states, cities, towns, counties, and all levels of jurisdiction. It uses the term "authority having jurisdiction." This makes me think that the section quoted was written as a local amendment to the NEC, and it's not surprising that a local amendment wouldn't makes sense because they are all too often written by people who have only a passing familiarity with the actual work, and zero ability to write cogent English sentences.
A ceiling grid IS just the grid -- not the tiles, and certainly not the roof. I don't know of any way wiring can be run "in" a grid system.
To save you looking back, here's the section quoted that purports to be from the NEC (but probably isn't):
NEC Article 90-13 Commercial Low Voltage
1. The Commercial Low Voltage Permit will apply to commercial, industrial, and muti-family complexes with three or more units.
2. Commercial low voltage installations that are associated with a project that has a building permit will not require a commercial low voltage permit.
3. Installation of new cable in an existing pathway will not require a permit as long as the existing pathways are in compliance with the codes.
4. Cable installations that do not penetrate fire walls, floors, or ceilings. or installed above ceiling grid systems will not require a permit. Installations within ceiling grid systems will require a Low Voltage Permit.
5. The City Building Department will provide a limited checklist with code references to assist inspectors and installers.
6. The first six months after the adoption of the ordinance, there will be a flat fee of $64 per commercial low voltage permit.
7. Commercial low voltage permit fees are based on the project cost which is the total cost of all labor and materials to complete the low voltage project. Electrical materials furnished by the owner must be included in the total low voltage project costs. Devices are not to be included in the total cost in determining the low voltage fee.
8. The commercial low voltage permit, once issued, shall become invalid unless the work on the site authorized by such permit is commenced within 180 days after its issuance, or if the work authorized on the site by such permit is suspended or abandoned for a period of 180 days after the work has commenced. The building official is authorized to grant in writing, one or more extensions of time, for a period not more than 180 days each. The extension shall be requested in writing and justifiable cause demonstrated.
