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The US-American regulations according to NFPA 79 for Industrial Machines are getting more flexible. In June 2011 the final review of 2012 edition was accepted in Boston Massachusetts. But the changes do not relax the situation for the European machine and plant construction industry regarding the use of „Appliance Wiring Material (AVM)“ in every case.
The NFPA Conference in Boston gave the public opportunity to argue against planned changes. After many discussions the „Report of Proposals“, elaborated by the experts´ working group was accepted and released. Printed copies should be available from September.
NFPA 79 edition 2012, including the now accepted changes, will be effective from end of July 2011. Whilst apparently offering more opportunities to the planner, the changes – summarized in a new paragraph – do not actually open many doors. According to the NFPA 79 edition 2007, valid up to now, the use of Appliance Wiring Material (AWM) – wires and cables considered recognized components for factory installed appliances – are explicitly prohibited in industrial machinery. Only cables approved and listed by National Recognized Testing Laboratories as e.g. UL (Underwriters Laboratories) and marked with the listed logo were permitted without additional testing.
Jörg Bör is Product Manager Cables at Lütze in Weinstadt.
Stefan Grunwald is Product Manager Industrial Cable at Lütze Inc., Charlotte (NC) and NFPA member.
AWM is classified as „recognized“.
Use of the „recognized“ logo means that the manufacturer confirms to produce the component according to specific UL specifications. AWM offers the opportunity to combine different insulation and jacket styles. This permits a high level of customization. Thus UL recognized cables are acknowledged as components but must be tested in field for a given specific application. This testing reveals whether the construction is suitable for the intended use. The styles defined by Underwriters Laboratories describe materials and construction of a cable as for example: - insulation and jacket wall thickness
- temperature range
- insulation material
- voltage
- fire performance
Alternatively a cable approved as „UL listed“ and marked with the appropriate logo is tested and approved for a specific application, thus the construction does not need specific testing in the field. It is checked only the conformity of the approval with the application (jacket printing!).
Over The Top?
There is no question that regulations such as NFPA 79 are necessary – however in the past the question has been raised as to whether NFPA in 2007 went too far with the general prohibition of AWM cables, especially regarding the wide range of applications such as use in drag chains or special cables, for which no listing exists up to now!
Finally the NFPA committee reacted to the industry´s complaints and put together a task group to reinstate the use of AWM when appropriate for the intended use. This has resulted in the new updated NFPA 79 edition 2012 which permits the use of AWM in industrial machines under special conditions.
The unlimited use of AWM is not permitted – as it was practiced before 2007. But the machine constructor is now able to take more responsibility. According to the new chapter 12.9 AWM is permitted when suitable for the intended used and marked appropriately. This can be the case if the cable - is part of a listed assembly that has been identified for the intended use;
- is specified for the use with approved equipment and used in accordance with the equipment manufacturer´s instructions or;
- meets specific constructive requirements concerning conductor stranding, fire performance, insulation thickness and marking.
It is sufficient to comply with one of these requirements instead of meeting all requirements in combination.
But is this solution practicable in every case for European machine construction industry focused on the UL market? We believe not. Nevertheless the 2012 edition permits AWM under specified conditions, with the machine´s manufacturer taking responsibility for identification and documentation. The new NFPA 79 requires selecting proper AWM constructions and documenting the suitability for the intended use in the machine documentation. Often the use of AWM may require special inspections and confirmations, or bring about discussions with local authorities or assurance inspectors. Cable suppliers may have to make minor updates on the AWM cable print legends to mark the cable in compliance with NFPA 79.
For field installation it still will be the safest to rely on cable that is UL listed and verified for the intended use. UL listed components will make it easier to evaluate a machine in the field and will therefore remain a very important choice. UL listed cable will also eliminate the need for documentation that AWM may require.
 
The changes in the original wording
Part of the most important changes in NFPA 79 from 2007 edition to 2012 edition is the elimination of clause 12.2.7 altogether. Instead of this all elements of the Report of Proposals are added in a new clause 12.9. Here the original text of this new section:
12.9 Special Cables and Conductors
12.9.1 Other listed cables and conductors shall be permitted where identified as suitable for the identified use.
12.9.2 Appliance Wiring Material (AWM) shall be permitted under 12.9.2.1 through 12.9.2.3
12.9.2.1 Where part of an assembly that has been identified for intended use
12.9.2.2 Where specified for use with approved equipment and used in accordance with the equipment manufacturers instructions.
12.9.2.3 Where its construction meets all applicable requirements of sections 12.2 – 12.6 with modifications as follows:
(1) Stranded conductors with wire sizes smaller than those listed in 12.2.2 shall have a minimum of 7 strands.
(2) Conductor insulation and cable jacket materials not specified in 12.3.1 have flame resistant properties in compliance with applicable standards for intended use such as FT2 (horizontal wire) flame test or VW-1 (Vertical Wire) flame test in ANSI/UL 1581-2001, Reference Standard for Electrical Wires, Cables and Flexible Cords.
(3) Minimum insulation thickness for single conductor AWM shall be as specified in 12.3.2. Minimum insulation thickness for conductors that are part of a multi conductor jacketed AWM cable shall be as specified by the AWM Style number and by the marked voltage rating of the cable.
(4) AWM shall be marked in accordance with 12.4.1, 12.4.3 and 12.4.4. The legend shall include manufacturer’s name or trademark, AWM style number, voltage rating (unless marking is prohibited by 12.4.2), wire gauge(s), temperature rating and flame resistance. Additional markings for properties such as oil, water, UV and chemical resistance identifiers shall be permitted where in compliance with applicable standards for intended use. Where markings alone are insufficient to identify for the intended application, suitable information shall be included with the technical machine documentation.
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