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NC code says ASTM C 635 and ASTM 636.
Hanger (Suspension) Wires (figures 5a and 5b)
• Hanger and perimeter wires must be plumb within 1 in 6 unless (figure 5a)
counter sloping wires are provided (figure 5b). Source: ASTM C636 Section 2.1.4
• Hanger wires shall be 12 gage and spaced 4 feet on center or 10 gage
spaced 5 feet on center. Source: ASTM C636 Section 2.1
• Any connection device at the supporting construction shall be capable
of carrying not less than 100 pounds. Source: CISCA zones 3-4
• Powder Actuated Fasteners (PAFs) are an approved method of
attachment for hanger wires. Source: State of Oregon, Building Codes Division
• Terminal ends of each main beam and cross tee must be supported
within 8 inches of each wall with a perimeter wire (see figure 4 & 5 a).
Source: ASTM E580 Section 5.2.6
• Wires shall not attach to or bend around interfering material or equipment. A trapeze or equivalent device shall be used where obstructions preclude direct suspension. Trapeze suspensions shall be sized to resist the dead load and lateral forces appropriate for the seismic category. Source: ASTM E580 Section 5.2.7.4
Electrical fixtures
• Light fixtures weighing less than 10 pounds shall have one 12 gage hanger wire connected from the fixture to the structure above. This wire may be slack. Source: ASTM E580 Section 5.3.4
• Light fixtures weighing more than 10 pounds and less than 56 lbs. shall have two 12 gage wires attached at opposing corners of the light fixture to the structure above. These wires may be slack. Source: ASTM E580 Section 5.3.5
• Light Fixtures weighing more than 56 lbs. shall be supported directly from the structure above by approved hangers. Source: ASTM E580 Section 5.3.6
• Pendant mounted fixtures shall be directly supported from the structure above using a 9 gage wire or an approved alternate support without using the ceiling suspension system for direct support. Source: ASTM E580 Section 5.3.7
• Tandem fixtures may utilize common wires
https://www.nwcb.org/uploads/4/0/5/0...and_f_2013.pdf
