September 16, 2021
No More Gray: Low Voltage Wiring Changes
Author: C. Webster Marsh, contributor to the Lighting Controls Association
Upcoming code changes will require pink low-voltage wires instead of gray. Move is aimed to reduce confusion and increase safety.
0-10V dimming wires, the wires used to communicate dimming intensity via a 10-volt signal, can be easily identified on wiring diagrams, installation instructions, and dimmable drivers by their colors: gray and violet (although violet is often referred to as purple). This will soon change, however, as new codes and guidelines take effect.
What Will Change?
All gray control conductors for 0-10V will change to pink.
Currently, 0-10V dimming uses a gray and violet pair of wires to connect luminaires, drivers, and devices. This color coding will change to a new standard, which will use a pink wire in lieu of the gray wire.
Who Decided On This Change?
The change was in response to the new electrical code: 2020 Edition of NFPA 70 (NEC) Article 410.69.
2020 NEC requires that where 0-10V or other controls wires share the same luminaire or enclosure as the branch-circuit wires, the wires powering the driver, the color gray will only be reserved for the branch-circuit wires. The gray conductor of 0-10V wiring would not be in compliance with this new requirement, and so the National Electric Manufacturers Association (NEMA) is changing its guidelines for 0-10V dimming wire colors. This change was announced in a bulletin approved on April 16, 2020 [hyperlink to bulletin].
When Does it Take Effect?
This requirement goes into effect on January 1, 2022.
NEMA is advising that manufacturers adopt the change “… as expeditiously as possible to ensure all necessary changes are made by January 1, 2022.” and installers “… should consider re-identification of gray control conductors using marking tape, painting, or other effective means as permitted…” in advance of the effective date.
What Colors are Acceptable?
NEMA is advising via their standard NEMA 100-2021 [hyperlink to standard] that the following colors be implemented for 0-10V control conductors. Please note that the color often referred to as “purple” is defined in this standard as “violet”, which is why I am referring to it as such:
What Do I Do with My Gray Wires Right Now?
NEC allows for “… marking tape, painting, or other effective means at [the conductor’s] termination and at each location where the conductor is visible and accessible.”
NEC also allows, under Article 90.4 that in the absence of available products, the Authority Having Jurisdiction (AHJ) may permit the use of “… products, constructions, or materials that comply with the most recent previous edition of this Code…”. In this case, it may apply to products such as Luminary MC cables which are prefabricated to have all conductors pre-installed in a flexible conduit. If no such product is available with the pink conductor, then the AHJ may permit alternatives until versions with pink are available.
While this change will impact the lighting industry for a brief period of time as everyone shifts to adapt, the benefits of this change should be readily apparent. Miswiring low voltage and branch circuit conductors can be a serious and life-threatening mistake, which is why NEC made this new requirement.
Additionally, NEMA’s new guidance in response to NEC facilitates consistency in the industry, so that rogue players don’t introduce a competing color, such as yellow. NEMA may not be code, but confusion can be mitigated by staying in compliance with their standards.
Finally, this is a good moment to take a mental snapshot. Older installations will be easily identifiable by their gray 0-10V wires and may one day be an indicator to replace outdated hardware, much like fluorescent lighting is today.
The Lighting Controls Association is a council of the National Electrical Manufacturers Association that provides education about lighting control technology and application, including articles, videos, design awards, news, resources, and Education Express, a free, 24/7 series of online courses covering everything from technology to design to commissioning.
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