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Article 692

Fuel Cell Systems

Part I. General

  1. Scope. This article applies to the installation of fuel cell systems.Informational Note: Some fuel cell systems can be interactive with other electrical power production sources, are stand-alone, or both. Some fuel cell systems are connected to electric energy storage systems such as batteries. Fuel cell systems can have ac output(s), dc output(s), or both for utilization.
  2. Definitions.

Fuel Cell. An electrochemical system that consumes fuel to produce an electric current. In such cells, the main chemical reaction used for producing electric power is not combustion. However, there may be sources of combustion used within the overall cell system, such as reformers/fuel processors.

Fuel Cell System. The complete aggregate of equipment used to convert chemical fuel into usable electricity and typically consisting of a reformer, stack, power inverter, and auxiliary equipment.

Interactive System. A fuel cell system that operates in parallel with and may deliver power to an electrical production and distribution network. For the purpose of this definition, an energy storage subsystem of a fuel cell system, such as a battery, is not another electrical production source.

Maximum System Voltage. The highest fuel cell inverter output voltage between any ungrounded conductors present at accessible output terminals.

Output Circuit. The conductors used to connect the fuel cell system to its electrical point of delivery.

Informational Note: In the case of sites that have series- or parallel-connected multiple units, the term output circuit also refers to the conductors used to electrically interconnect the fuel cell system(s).

Point of Common Coupling. The point at which the power production and distribution network and the customer inter‐ face occurs in an interactive system. Typically, this is the load side of the power network meter.

692.4 ARTICLE 692 — FUEL CELL SYSTEMS

Stand-Alone System. A fuel cell system that supplies power independently of an electrical production and distribution network.

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692.4 Installation.

  1. Fuel Cell System. A fuel cell system shall be permitted to supply a building or other structure in addition to any serv‐ ice(s) of another electricity supply system(s).
  2. Identification. A permanent plaque or directory, denot‐ ing all electric power sources on or in the premises, shall be installed at each service equipment location.
  3. System Installation. Fuel cell systems including all associ‐ ated wiring and interconnections shall be installed by only qualified persons.

Informational Note: See Article 100 for the definition of quali‐ fied person.

692.6 Listing Requirement. The fuel cell system shall be listed or field labeled for its intended application.

Part II. Circuit Requirements

  1. Circuit Sizing and Current.
    1. Nameplate Rated Circuit Current. The nameplate(s) rated circuit current shall be the rated current indicated on the fuel cell nameplate(s).
    2. Conductor Ampacity and Overcurrent Device Ratings. The ampacity of the feeder circuit conductors from the fuel cell system(s) to the premises wiring system shall not be less than the greater of (1) nameplate(s) rated circuit current or(2) the rating of the fuel cell system(s) overcurrent protective device(s).
    3. Ampacity of Grounded or Neutral Conductor. If an inter‐ active single-phase, 2-wire fuel cell output(s) is connected to the grounded or neutral conductor and a single ungrounded conductor of a 3-wire system or of a 3-phase, 4-wire, wye- connected system, the maximum unbalanced neutral load current plus the fuel cell system(s) output rating shall not exceed the ampacity of the grounded or neutral conductor.
  2. Overcurrent Protection.
    1. Circuits and Equipment. If the fuel cell system is provided with overcurrent protection sufficient to protect the circuit conductors that supply the load, additional circuit overcurrent devices shall not be required. Equipment and conductors connected to more than one electrical source shall be protec‐ ted.
    2. Accessibility. Overcurrent devices shall be readily accessi‐ ble.
  3. Stand-Alone Systems. The premises wiring system shall meet the requirements of this Code except as modified by 692.10(A), (B), and (C).
  1. Fuel Cell System Output. The fuel cell system output from a stand-alone system shall be permitted to supply ac power to the building or structure disconnecting means at current levels below the rating of that disconnecting means.
  2. Sizing and Protection. The circuit conductors between the fuel cell system(s) output and the building or structuredisconnecting means shall be sized based on the output rating of the fuel cell system(s). These conductors shall be protected from overcurrents in accordance with 240.4. The overcurrent protection shall be located at the output of the fuel cell system(s).
  3. Single 120-Volt Nominal Supply. The inverter output of a stand-alone fuel cell system shall be permitted to supply 120 volts, nominal, to single-phase, 3-wire 120/240-volt service equipment or distribution panels where there are no 240-volt loads and where there are no multiwire branch circuits. In all installations, the rating of the overcurrent device connected to the output of the fuel cell system(s) shall be less than the rating of the service equipment. This equipment shall be marked as follows:

WARNING

SINGLE 120-VOLT SUPPLY. DO NOT CONNECT MULTIWIRE

BRANCH CIRCUITS!

The warning sign(s) or label(s) shall comply with 110.21(B).

Part III. Disconnecting Means

692.13 All Conductors. Means shall be provided to disconnect all current-carrying conductors of a fuel cell system power source from all other conductors in a building or other struc‐ ture.

692.17 Switch or Circuit Breaker. The disconnecting means for ungrounded conductors shall consist of readily accessible, manually operable switch(es) or circuit breaker(s).

Where all terminals of the disconnecting means may be energized in the open position, a warning sign shall be moun‐ ted on or adjacent to the disconnecting means. The sign shall be clearly legible and shall have the following words or equiva‐ lent:

DANGER

ELECTRIC SHOCK HAZARD. DO NOT TOUCH TERMI‐ NALS.

TERMINALS ON BOTH THE LINE AND LOAD SIDES MAY BE ENERGIZED

IN THE OPEN POSITION.

The danger sign(s) or label(s) shall comply with 110.21(B).

Part IV. Wiring Methods

692.31 Wiring Systems. All raceway and cable wiring methods included in Chapter 3 of this Code and other wiring systems and fittings specifically intended and identified for use with fuel cell systems shall be permitted. Where wiring devices with integral enclosures are used, sufficient length of cable shall be provided to facilitate replacement.

Part V. Grounding

692.41 System Grounding.

  1. AC Systems. Grounding of ac systems shall be in accord‐ ance with 250.20, and with 250.30 for stand-alone systems.
  2. DC Systems. Grounding of dc systems shall be in accord‐ ance with 250.160.
  3. Systems with Alternating-Current and Direct-Current Grounding Requirements. When fuel cell power systems have both alternating-current (ac) and direct-current (dc) ground‐ ing requirements, the dc grounding system shall be bonded to the ac grounding system. The bonding conductor shall be sized according to 692.45. A single common grounding electrode and grounding bar may be used for both systems, in which case the common grounding electrode conductor shall be sized to meet the requirements of both 250.66 (ac) and 250.166 (dc).
  1. Equipment Grounding Conductor. A separate equip‐ ment grounding conductor shall be installed.
  2. Size of Equipment Grounding Conductor. The equip‐ ment grounding conductor shall be sized in accordance with 250.122.

692.47 Grounding Electrode System. Any auxiliary grounding electrode(s) required by the manufacturer shall be connected to the equipment grounding conductor specified in 250.118.

Part VI. Marking

  1. Fuel Cell Power Sources. A marking specifying the fuel cell system, output voltage, output power rating, and continuous output current rating shall be provided at the disconnecting means for the fuel cell power source at an acces‐ sible location on the site.
  2. Fuel Shut-Off. The location of the manual fuel shut- off valve shall be marked at the location of the primary discon‐ necting means of the building or circuits supplied.

692.56 Stored Energy. A fuel cell system that stores electrical energy shall require the following warning sign, or equivalent, at the location of the service disconnecting means of the prem‐ ises:

WARNING

FUEL CELL POWER SYSTEM CONTAINS ELECTRICAL ENERGY STORAGE DEVICES.

The warning sign(s) or label(s) shall comply with 110.21(B).

and shall not feed the electrical production and distribution network side of the point of common coupling during this condition. The fuel cell system shall remain in that state until the electrical production and distribution network voltage has been restored.

A normally interactive fuel cell system shall be permitted to operate as a stand-alone system to supply loads that have been disconnected from electrical production and distribution network sources.

  1. Unbalanced Interconnections. Unbalanced intercon‐ nections shall be in accordance with 705.100.
  2. Utility-Interactive Point of Connection. Point of connection shall be in accordance with 705.12.

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