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2020 NEC changes affecting hazardous locations installations

Top five questions to help navigate the changes to the 2020 National Electrical Code©.

oil rig on shore

September 20, 2019

Staying up-to-date on upcoming changes to the 2020 Edition of the NFPA 70, the National Electrical Code©. UL is here to help you understand revisions to markings, area classification, code definitions, and equipment ratings, as well as important updates related to protection methods. We will help you prepare for these changes related to hazardous (classified) locations.

Here are the top five questions that will help manufacturers and installers navigate the changes to the 2020 National Electrical Code©.

  1. I see that UL 2225 is a relevant standard for cables and cable fittings.  What sort of status does UL 2225 have in world-wide applications?

    Since UL 2225 covers cables and cable fittings with respect to NEC-based wiring methods, its use is generally restricted to locations that require such methods. Examples include the U.S. (including references made by U.S. Coast Guard and API requirements), Mexico, some parts of Central and South America, some parts of Asia, and some locations in the Middle East. Since the NEC references UL 2225, cables listed to that standard may be required by the Authority Having Jurisdiction.


The UL 2225 standard covers MC-HL cable, ITC-HL cable, TC-ER-HL cable, and glands, seals, and fittings for those cables plus flexible cords and marine shipboard cable for protection methods explosionproof, dust-ignition proof, flameproof, increased safety, and “t” enclosure. The majority of other locations use installation requirements based on IEC 60079-14, which describes the requirements for cables in hazardous locations, but does not require cables to be certified. Glands and fittings are required to be certified when the type of protection depends on them, e.g. for flameproof or increased safety installations; the requirements for these glands are in the corresponding 60079-series of standards.

  1. On the slide with new marking strings for ANSI/UL 60079 standards, Encapsulation “m”, only mb and mc were shown for new markings. What about “ma” for Encapsulation Zone 0? Is that allowed in the NEC?

Yes, “ma” is allowed by the NEC, but requires intrinsically safe wiring to the “ma” device when located in a Zone 0 location, limiting its practical use at this time (i.e. only intrinsically safe wiring is allowed in a Zone 0 location in the NEC).  Encapsulation as a method had already been updated so the current 2017NEC allows “m,” “ma,” “mb,” and “mc” methods. 

  1. What's the timeline for updating UL2225?   

    We plan to begin the revision process for UL 2225 in September 2019.  We would expect the revisions to be published in early 2020.
  2. In the U.S. for Hazardous Locations, are equipment with Zone classifications acceptable without traditional Class/Div?

    Yes, the NEC has reciprocity allowances to put Zone-certified equipment into a Division-classified location and vice-versa.  However, the allowances are limited by the definitions of the different Divisions and Zones.  For example, a Zone 1 product is not acceptable for use in a Division 1 location, since it would not be safe to install Zone 1 equipment in the part of the Division 1 location that would be Zone 0 in the Zone system.  However, a Division 2 product could be installed in a Zone 2 and a Zone 2 product could be installed in a Division 2.  See Articles 501.5 and 505.20 for more details. 
  3. Which article is on Combustible detector?  allowing lower protection equipment.

    In the current 2017 NEC, Article 500.7(K) covers combustible gas detection for Division locations.  In the 2020 NEC, it will remain there for Divisions and will be added into 505.8 for Zones.

For more information, listen to UL’s free on-demand webinar and learn how to prepare for the 2020 NEC.

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