Frequently Asked Questions

• 1. What are the standards that address use of Class 2, DC power distribution in commercial buildings?

  The National Electric Code®(NEC®) addresses this in section 393.6 (B). The NEC defines Class 2 as the portion of the wiring system between the load side of a listed Class II Power Supply, listed low-voltage cables and the Class 2 electrical equipment. Power, current and voltage limitations of a Class 2 circuit addresses safety from a fire initiation standpoint and provide acceptable protection against electric shock.

• 3. How do electrical drawings reflect the DC2DC architecture?

  Electrical drawings show the DCHUB (instead of power packs), and document Class 2 cabling in relationship to luminaires.

• 4. What makes the DC2DC architecture unique compared to other DC-powered lighting systems?

  The DC2DC architecture offers unique features including:

  • Multiple luminaires of the same or different types, on the same power and control run, can be independently controlled, up to the limit of the Class 2 circuit
  • Luminaires can be individually controlled or grouped in zones, with up to 16 independent control channels for luminaires with Static CCT or up to 8 channels for luminaires with Tunable White.
  • Ability to leverage Wired networked lighting controls by nLight, connecting luminaires, sensors, and other control devices to create a distributed digital network.
  • The architecture uses standard Class 2 cabling, which can be field cut from a spool.
  • 3-port levered wire connectors in the luminaires allow for easy daisy chaining of loads
  • Luminaires can be installed in inaccessible ceilings with all electrical connections accessed from below.
  • The DCHUB takes only 6 inches of plenum depth and can be grid mounted horizontally. The DCHUB is UL listed for installation in a return air plenum

• 5. Is Acuity Brands DC2DC architecture only compatible with Acuity Brands luminaires?

  No. Any luminaire utilizing a 57 VDC driver by eldoLED®, is compatible with Acuity Brands’ DC2DC architecture.

• 6. How is the DCHUB DC2DC architecture different from the Modulus™ Head Unit?

  For comparison:

  • The Modulus unit is a Class 1 DC supply (Over 100 VA) and requires conduit between the head end and the luminaire. With the DC2DC architecture, wiring between the DCHUB and the luminaires is Class 2 and does not require conduit.
  • A Modulus head end is an accessory to a single luminaire. A DC2DC DCHUB is ordered independently from the luminaires and can serve multiple luminaires of different types.
  • Modulus has only a single output, and is limited to 320 VA. A DC2DC DCHUB can have up to 12 outputs and manages up to 1080 VA with runs in a star topology.

• 7. How is the DC2DC architecture different from PoE lighting systems?

  For comparison:

  • PoE systems that use racks in IT closets may not be built during the construction phase of the project when temporary lighting is needed. The DC2DC DCHUB and compatible luminaires are available for rough in and temporary lighting needs.
  • For information security reasons, IT racks providing PoE power may not be easily accessible by the electrical contractor for providing lighting power and commissioning.
  • PoE systems typically use Category 5/6/7 cable and RJ45 connectors with a home run per device (luminaire or control). The DC2DC architecture uses Class 2 cable, 16 AWG conductors with levered wire connectors in the luminaire and allows daisy chaining of luminaire up to the full power limit of a DCHUB port.
  • At a single end device, PoE type 1 provides 12.95W, type 2 provides 25.5W, Type 3 provides 51W and Type 4 71.3W. https://en.wikipedia.org/wiki/Power_over_Ethernet . A DC2DC DCHUB provides up to 90 VA to either a single or multiple end devices.
  • PoE systems require IT infrastructure for control of lighting. The DC2DC architecture employs wired and wireless nLight distributed control for real time control needs and does not require IT infrastructure for lighting control. This simplifies project management and allows the installation of the DC-powered lighting systems to obtain a certificate of occupancy before the IT infrastructure is installed and ready.
  • PoE systems allow (at a cost) a high-speed data connection to the luminaire, which is far more than what is required for normal lighting needs. The DC2DC architecture provides a right-sized data connection for lighting control.
  • Some PoE systems require external control wiring from sensors and switches to terminate in the luminaire driver compartment, making controls installation time consuming. The DC2DC architecture uses embedded sensors that are factory-wired to the driver, or separate sensors on the local control network.
  • PoE systems are often challenging to implement in terms of emergency lighting. The DCHUB with nPS80 DALI ER 57VDC control, enables support of emergency lighting.
  • PoE systems energy losses through cabling are high, lowering the efficiency of the installation. The DC2DC architecture cabling losses are less than half those of the PoE cabling, arising from the better conductivity of single pair 16 AWG as compared to multiple pair 24 AWG.

• 8. What is the wattage limitation of a single DCHUB

  The DCHUB, based on the version ordered, contains at least 2 and up to 12, 90VA, 57VDC power outputs that can feed up to 1080VA of DC-powered LED luminaires.

• 9. When are DC-powered lighting systems effective for renovation?

  If the building is being taken down to structure, then the DC2DC architecture provides the same benefits in renovation as new construction. If the renovation allows the reuse of existing AC wiring infrastructure, then it is usually more cost effective to complete the renovation with traditional AC infrastructure.

• 10. Why does the DC2DC architecture utilize 57 VDC rather than 24 VDC?

  57 VDC was selected because:

  1. It falls below the maximum of 60 VDC allowed in NEC Class 2 installations with a 5% safety margin. This is the same maximum voltage maximum utilized by PoE systems.

  2. Efficiency lost in conductors is related to the square of the current flowing through them. 57 VDC loss in 100’ run at 90 VA is under 2 Watts, 24 VDC is 11 Watts under the same conditions.

  3. Drivers utilized in the DC2DC architecture are compatible with the widest array of Class 2 LED modules, without having to boost the voltage within the luminaires. They are also more cost effective and efficient because the drivers operate only in buck mode.

• 11. When designing a DC-microgrid, which DCHUB models are available for 250 VDC operation? 

  Currently, a surface-mounted, non-recessed DCHUB is available with 250 VDC input, Consult Acuity for specific details and coordination of systems.

• 12. Are luminaires with nLight® AIR controls compatible with the DC2DC architecture?

  Yes, luminaires available with both an nLight AIR control device and including a 57V DC2DC driver are compatible.

• 13. In new construction of a school, where the DC2DC architecture is only being considered for a classroom, how would I address lighting requirements in other spaces? 

  We recommend a hybrid approach involving a DC2DC architecture for classrooms, and high voltage AC-powered luminaires with wired nLight® or wireless nLight AIR controls in areas such as outdoor, gymnasiums, auditoriums, cafeterias and hallways, for the most cost-effective implementation. The DC2DC architecture can be used within a hybrid implementation of DC and AC powered lighting systems within one building. It is part of a unified platform through networked lighting controls by nLight, enabling building-wide control and lighting strategies.

• 14. The DCHUB previously included options for embedded nIO(s). Why are nIO options no longer shown on the data sheet?

  With the addition of wireless nLight AIR controls and the introduction of the 57VDC nPS80 DALI in the wired nLight controls option, the nIO option is no longer the preferred DC2DC architecture.

  Distributing the controls reduces overall cost, simplifies commissioning and better leverages the industry leading controls from nLight. Legacy installations desiring an embedded nIO can still order the option to control luminaires specified with the DCHUB control input option.

• 15. Can you explain more about the “Installation Requirements” option on the nPS80 DALI?

  The preferred method for a 57V Class 2 input, as is the case with DC2DC, is to exit the DALI wires through the chase nipple. Since the 57VDC supply from the DCHUB is Class 2, the DALI wires are also Class 2. Exiting the wires through the chase nipple and making the connections in the junction box used to mount the device will eliminate splices in the plenum. You should use the CLSS2 side exit option only when the input voltage is Class 1, and the DALI wires need to be Class 2.

• 16. How is Tunable White accomplished with DC2DC architecture?

  The nPS80 DALI 8ZCCT 57VDC enables CCT control of 57 VDC luminaires with the DALI8 option to comply with IEC 62386, part 209 (DT8). Please note that Tunable White 57VDC luminaires with the DCHUB option use DT6 protocol and are only compatible with the nIO 8Z CCT.

• 17. Can I design a DC2DC solution using Visual Controls?

  Yes, DC2DC is supported in Visual Controls for designing lighting controls for a space and simplifying controls drawing packages.

• 18. Can DC2DC be used in applications other than school classrooms?

  Yes, DC2DC architecture is being successfully used in millions of square feet of corporate office renovations, hospitals and medical office buildings for installation of downlights, lay-in, surface, night lights, exit signs, recessed slot, pendant custom lighting fixtures and more! DC2DC is not yet practical for high lumen output industrial fixtures or outdoor lighting installations.

• 19. Are 57VDC powered LED luminaires from Acuity Brands and nLight controls able to be powered by third party power supplies?

  Provided that the third-party power supply:

  • Meets UL and NEC requirements for Class 2 power supply
  • Delivers a minimum of 52VDC after voltage drop at the fixture access plate
  • Meets specific project requirements (UL 924, 2108 and 2043 listing, plenum, etc.)
  • Provides adequate load (watts) to downstream luminaire(s) including inrush and cold temperature starting current
  • Is tested by the third-party manufacturer with a fully loaded complement of Acuity fixtures
  • Manufacturer accepts responsibility for a properly operating system when used with eldoLED drivers and nLight controls under the conditions of the project
  • Specifying a complete DC2DC Architecture from Acuity is the best path to ensure compatibility and a seamless customer experience from specification through installation and owner occupation. The following items should be considered when specifying a DC system utilizing 3rd party components:
    • Multiple points of communication and coordination
    • System power/communication compatibility
    • Shared architecture responsibility across a range of suppliers
    • Different VC (Visual Control) layout rules
    • Alternative response behaviors due to faults such as (but not limited to) overload circuits, mis-wired, cross-wired, and short circuits
    • Multiple points of communication and provided service to address field and warranty-related issues