[NEC 110.12] and that conductors are not exposed to physical damage [NEC 300.4]. Physical damage is not specifically defined in the NEC or in ANSI/NECA 1-2010; however, it is generally understood as being self-defined. … In a large PV power plant, the perimeter fencing and security system that keeps unqualified people out of the facility is sufficient to prevent physical damage due to unqualified persons. … Given the large amount of exposed dc cable used in PV arrays, it is understandable that wiring methods are as simple and cost effective as possible to keep installation and maintenance costs to a minimum”. Bill Brooks White Paper: Cable Management in Solar PV Arrays, Pages 2-3, Jan. 16, 2014
Q: What are the spacing requirements for CAB Cable Rings and Saddles?
A: NEC Article 690.31(C)(2) addresses support and securement requirements which apply to Cable Tray and Cable Rings and Saddles. A maximum spacing of 12” should be used for cable sizes less than 1/0 AWG. A maximum spacing of 18” should be used for cable sizes greater than 1/0 AWG. The same article requires securement intervals no larger than 4.5 feet for USE-2 and PV Wire. Bill Brooks White Paper: Cable Management in Solar PV Arrays, Pages 5-6, Jan. 16, 2014
Q: Can AC and DC conductors be run together in the same bundle?
A: There is a significant change in the 2014 NEC that disallows AC and DC conductors to be installed together in the same raceway or enclosure unless they are separated by a partition. The CAB Cable Ring system allows for two different lengths of Cable Rings to be installed from the same messenger wire. This effectively creates the separation between the AC and DC cables that is necessary. Bill Brooks White Paper: Cable Management in Solar PV Arrays, Page 6, Jan. 16, 2014
Q. How is ampacity of conductors calculated for bundles of cables in CAB Cable Rings and Saddles?
A. “As cables are bundled together, the inner conductors are not in free air and their ampacity is similar to conductors in a raceway. Therefore, to be conservative, a cable bundle of three cables should be subject to the ampacity limitations of Table 310.15(B)(16) which is used for up to three conductors in a raceway. Since outdoor ambient design temperatures are generally above 30 degrees C for most of the United States, an additional correction factor for temperature should be applied according to Table 310.15(B)(2)(a). For more than three cables in a bundle, Table 310.15(B)(3)(a) should adjust the ampacity further. This may be a conservative interpretation, but the NEC is not specific on this issue.” Further detailed information on this subject is covered on page 9 in Bill Brooks White Paper. Bill Brooks White Paper: Cable Management in Solar PV Arrays, Page 9, Jan. 16, 2014
Q: Can I use cable ties to secure and support my cables?
A: ANSI/NECA 1-2010 standard (q) states: When using cable ties, do not over tighten, to ensure the cable tie does not cut the conductor’s outer jacket. Cable ties shall not be used to support raceways or cables. “It is the recommendation of this standard that cable ties not be used to support cables. It is common to see cable ties used in PV installation as the sole method of support. While it is not specifically disallowed in the NEC, this industry standard does not allow it.” Bill Brooks White Paper: Cable Management in Solar PV Arrays, Page 4, Jan. 16, 2014
Q: What are the grounding and bonding requirements for CAB Cable Rings and Saddles?
A: CAB Cable Rings and Saddles fall under the definition of “fitting” in Article 100 of the NEC. A fitting is an accessory such as a locknut, bushing or other part of a wiring system that is intended primarily to perform a mechanical rather than an electrical function. In his White Paper, Bill Brooks expands on this subject, “Some AHJs may request that exposed metal rings and saddles be evaluated for bonding, but this is not well substantiated in the NEC, nor is there a UL standard for evaluating such equipment. … The NEC simply states in Article 334.30 that, Nonmetallic-sheathed cable shall be supported and secured by staples, cable ties, straps, hangers, or similar fittings designed and installed so as not to damage the cable…. Clearly, damage to the cable is the issue. Given this line of reasoning, a cable hanger or similar fitting such as CAB Cable Rings and Saddles could be installed without a listing for bonding and grounding. … Ultimately, the AHJ must approve any equipment used in a PV installation under their purview. If an AHJ will not accept cable rings and saddles as being designed to prevent damage to the cable, a simple way to resolve the need for bonding this product is to coat the product with a durable non-conductive coating so that the metal of the rings and saddles never comes in contact with the cable. An example of CAB Cable Rings and Saddles with this type of coating is shown in Figure 4.” (pictured: CAB 100% PVC Coated Cable Rings and Saddles). Bill Brooks White Paper: Cable Management in Solar PV Arrays, Pages 7-8, Jan. 16, 2014