Wiring and Cable Support.

These Class 2 control cables are permitted to be strapped to the power circuit supply conduit since both the cables and the conduit are associated with the HVAC unit.
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These Class 2 control cables are permitted to be strapped to the power circuit supply conduit since both the cables and the conduit are associated with the HVAC unit.

NFPA 731 Section 4.6.3.1 requires the installation of all wiring, cable, and equipment to be performed in accordance with NFPA 70 (NEC), Article 725 or Article 800, where applicable.

One requirement in NEC® 725.24 and 800.24 is that cables and conductors installed exposed on the surface of ceilings and sidewalls shall be supported by the building structure in such a manner that the cable will not be damaged by normal building use. Section 725.143 and 800.24 also require the support of cables to be in accordance with NEC® 300.11 which provides rules on when a cable can be strapped to the outside of a raceway.

Its quite common to see low voltage wiring methods strapped to an existing conduit especially above a suspended ceiling. Installers are known to grab a handful of zip ties and strap low voltage cables to anything they can when wiring above a grid ceiling.

NEC 300.11(C)(2) allows strapping a low voltage Class 2 cable to the outside of a raceway only if the raceway contains conductors that are also associated with the low voltage installation.

Below is a sample of NFPA 731. For the complete section, see the actual NFPA 731 text at NFPA.ORG. Once there, click on the free access link to the latest edition of NFPA 731.

4.6.3 Wiring.

4.6.3.5 Premises security system wiring and cables shall be of the gauge, strands, insulation, and electrical properties specified by the equipment manufacturer.

4.6.3.6 Connections of conductors to terminal parts shall ensure a tight, conductive connection without damaging the conductors and be made by means of pressure connectors, wire binding screws, or splices to flexible leads.

4.6.3.7 Conductors shall be connected to devices and to fittings so that tension is not transmitted to joints or terminals.

4.6.3.8 Wires and cables shall not be placed in such a manner as to prevent access to equipment.

Below is a sample of the NEC®. See the actual NEC® text at NFPA.ORG for the complete code section. Once there, click on their link to free access to the latest NEC® edition of NFPA 70.

725.143 Support of Conductors. Class 2 or Class 3 circuit conductors shall not be strapped, taped, or attached by any means to the exterior of any conduit or other raceway as a means of support. These conductors shall be permitted to be installed as permitted by 300.11(C)(2).

300.11(C) Raceways Used as Means of Support.

(2) Where the raceway contains power supply conductors for electrically controlled equipment and is used to support Class 2 circuit conductors or cables that are solely for the purpose of connection to the equipment control circuits.

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Wiring and Cable Support.

Below is a Real Question from our Electrical Continuing Education Courses for Electrical License Renewal:

Which of the following is true regarding security system wiring methods?

A: All low voltage security cables are permitted to be strapped to any raceway for support.
B: Only Class 2 control cables are permitted to be strapped to the associated power supply conduit for the same equipment.
C: Security system cables can be strapped to any conduit above a suspended ceiling.
D: Security system cables are not required to be secured or supported.
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