Workspace Clearances and Accessibility: Page 3 of 3

Intermediate
Thirty inches width is required in front of electrical equipment
Thirty inches width is required in front of electrical equipment; this zone can overlap with the workspace width of other pieces of equipment, but must not interfere with opening the enclosure covers.
Power sheds shouldn't be used for storage
Numerous hazards—as well as Code violations—typically occur when power sheds are used for storage. Violations in this photo are numerous, including exposed and accessible live terminals, unprotected conductors, and lack of workspace clearances.
This does not meet workspace clearance requirements.
The beam in front of these roof-mounted combiner boxes makes them more difficult to work on and does not meet workspace clearance requirements.
Ensure adequate ventilation around inverters.
Follow the manufacturer’s installation instructions to ensure adequate ventilation around inverters.
ollow the manufacturer’s instructions for placement and temperature limitations
Required to be accessible, but not readily accessible, combiner boxes are frequently mounted on roofs. Follow the manufacturer’s instructions for placement and temperature limitations to ensure that they maintain their NEMA rating.
Thirty inches width is required in front of electrical equipment
Power sheds shouldn't be used for storage
This does not meet workspace clearance requirements.
Ensure adequate ventilation around inverters.
ollow the manufacturer’s instructions for placement and temperature limitations

Accessibility & PV Systems

Section 690.31(A) requires PV source and output circuits greater than 30 volts (per the Section 690.7 maximum system voltage calculation) to be contained in a raceway if they are readily accessible. In reality, this requirement can’t be met with the majority of PV modules on the market, which have prewired, quick-connect leads—there is nowhere to connect a raceway to the junction box on the back of the module.

Systems on residential rooftops are typically not considered readily accessible, thus this requirement does not apply. However, module interconnects and home runs on pole- and ground-mounted PV arrays must not be readily accessible if they are to comply. For a pole-mounted system, making it tall enough so a ladder is required to reach the wires will meet the requirement. Making the wiring inaccessible can also be accomplished by putting a fence around the array, or by using lattice, another type of screening, or an enclosed cable tray so that a tool is required to remove hardware and material to access the conductors. Check with the authority having jurisdiction (AHJ) to verify that the measures employed will meet their requirements for rendering the wiring non-readily accessible.

There are a few exceptions, but, in general, Section 404.8(A) requires switches and circuit breakers to be readily accessible and limits the height of their operating handle to no more than 6 feet 7 inches above the platform or working surface from which they are accessed. However, Sections 690.14(D) and 705.70 permit inverters to be installed in non-readily accessible locations. This is a common scenario in residential PV systems where microinverters may be mounted behind modules, or in commercial PV systems where string inverters may be mounted on a parapet wall on a low-sloped roof. In these cases, DC and AC disconnecting means are required either within sight of—defined in Article 100 as “visible and not more than 50 feet away from”—or integrated into the inverter. Since they are equipment disconnects, they must be grouped with the inverter. Depending on the particular string inverter, a combination of internal (such as a built-in DC disconnect, which may or may not also disconnect the AC conductors) and/or external (most commonly, an external AC disconnect switch) is used. With microinverters, the plug connectors on the microinverters must be listed and identified to meet this disconnect requirement (per the Exception to Section 690.17 and the requirements of 690.33). An additional disconnect for the inverter output circuit of roof-mounted (not readily accessible) inverters is required. It must meet the requirements of Sections 690.14(C)(1), 690.17(1) and 705.22, which apply to disconnecting means for PV systems and require them to be readily accessible: installed either on the outside of a building or inside at a readily accessible point, and as close as possible to the entry point of the system’s conductors.

Section 690.31(E) requires that DC PV source and output circuits installed inside of a building be contained in a metallic raceway or enclosure, or be metal-clad (MC) cable until the first readily accessible disconnect. This provides additional protection and an enhanced ground-fault current path to sections of the circuit that cannot be easily de-energized.

Section 690.7(D) applies to one- and two-family dwellings, and requires that live parts in DC PV system circuits greater than 150 V not be readily accessible when energized, except to qualified personnel. This requirement can easily be met with raceways and/or enclosures like junction boxes that require a tool to open.

Section 690.9(C) requires series fusing for PV source circuits to be accessible, but not readily accessible. Thus, combiner boxes can be mounted on a residential roof that requires a ladder to access.

Section 480.5 requires disconnecting means for the ungrounded conductors connected to storage batteries to be readily accessible and within sight of the batteries. Live parts operating above 50 V must be protected in accordance with Section 110.27 by being:

  • Located in a room or enclosure (such as a battery box) accessible only to qualified personnel.
  • Behind partitions or screens that permit only qualified personnel within reach of the energized parts.
  • Elevated (to 8 feet or more) so that they are out of reach of unqualified personnel.

When the Section 110.27 requirement is met by locating the batteries in a room or enclosure, “conspicuous warning signs forbidding unqualified persons” from entering the room or opening the enclosure must be posted per Section 110.27(C).

Workspace clearances around batteries must also follow Section 110.26. A note in Section 480.9(C) states that measurements for clearances are made from the edge of the battery bank rack or enclosure.

Access

Brian Mehalic is a NABCEP-certified PV professional and ISPQ-certified PV instructor. He has experience designing, installing, servicing, and inspecting all types and sizes of PV systems. He is a curriculum developer and instructor for Solar Energy International and a project engineer for O2 Energies.

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