690.12(A&B) Rapid Shutdown of PV Systems on Buildings.
Code Change Summary: The rules on Rapid shutdown have been expanded.
Rapid shutdown was first introduced in the 2014 NEC® with the intent of providing a simple method for a first responder to de-energize PV system conductors easily and quickly to ensure a safe condition on the roof of a building during a fire. The rule was aimed at PV system conductors greater than 10 feet from an array of more than 5 feet inside a building because the further the conductors are from where they originate, the more difficult it becomes to keep track of where they are in relation to the rooftop PV modules.
In the 2017 NEC®, rapid shutdown has been expanded with different requirements based on how close the PV system conductors are to the PV array boundary which is now defined as the area 1 foot from the array in all directions.
PV circuits located outside the boundary or more than 3 feet from the point of entry inside a building shall be limited to not more than 30 volts within 30 seconds of rapid shutdown initiation.
For PV circuits located inside the array boundary, one of the following three options must be used beginning with an effective date of January 1, 2019:
- The PV array shall be listed or field labeled as a rapid shutdown PV array. Such a PV array shall be installed and used in accordance with the instructions included with the rapid shutdown PV array listing or field labeling.
- PV conductors located inside the boundary or not more than 3 feet from the point of penetration of the surface of the building shall be limited to not more than 80 volts within 30 seconds of rapid shutdown initiation.
- PV arrays with no exposed wiring methods, no exposed conductive parts, and installed more than 8 feet from exposed grounded conductive parts or ground shall not be required to comply with rule 2 above.
The delayed effective gives the nationally recognized testing labs time to create applicable test standards in order to list the products mentioned in rule 1 above. Currently there is no UL Standard that addresses a listed rapid shutdown PV array.
Below is a preview of the NEC®. See the actual NEC® text at NFPA.ORG for the complete code section. Once there, click on their link to free access to the 2017 NEC® edition of NFPA 70.
2014 Code Language:
690.12 Rapid Shutdown of PV Systems on Buildings. PV system circuits installed on or in buildings shall include a rapid shutdown function that controls specific conductors in accordance with 690.12(1) through (5) as follows.
(1) Requirements for controlled conductors shall apply only to PV system conductors of more than 1.5 m (5 ft) in length inside a building, or more than 3 m (10 ft) from a PV array.
(2) Controlled conductors shall be limited to no more than 30 volts and 240VA within 30 seconds of rapid shutdown initiation.
(3) Voltage and power shall be measured between any two conductors and between any conductor and ground.
(4) The rapid shutdown initiation methods shall be labeled in accordance with 690.56(B).
(5) Equipment that performs the rapid shutdown shall be listed and identified.
2017 Code Language:
690.12 Rapid Shutdown of PV Systems on Buildings. PV system circuits installed on or in buildings shall include a rapid shutdown function to reduce shock hazard for emergency responders in accordance with 690.12(A) through (D).
Exception: Ground mounted PV system circuits that enter buildings, of which the sole purpose is to house PV system equipment, shall not be required to comply with 690.12.
N (A) Controlled Conductors. Requirements for controlled conductors shall apply to PV circuits supplied by the PV system.
N (B) Controlled Limits. The use of the term array boundary in this section is defined as 305 mm (1 ft) from the array in all directions. Controlled conductors outside the array boundary shall comply with 690.12(B)(1) and inside the array boundary shall comply with 690.12(B)(2).
(1) Outside the Array Boundary. Controlled conductors located outside the boundary or more than 1 m (3 ft) from the point of entry inside a building shall be limited to not more than 30 volts within 30 seconds of rapid shutdown initiation. Voltage shall be measured between any two conductors and between any conductor and ground.
(2) Inside the Array Boundary. The PV system shall comply with one of the following:
(1) The PV array shall be listed or field labeled as a rapid shutdown PV array. Such a PV array shall be installed and used in accordance with the instructions included with the rapid shutdown PV array listing or field labeling.
(2) Controlled conductors located inside the boundary or not more than 1 m (3 ft) from the point of penetration of the surface of the building shall be limited to not more than 80 volts within 30 seconds of rapid shutdown initiation. Voltage shall be measured between any two conductors and between any conductor and ground.
(3) PV arrays with no exposed wiring methods, no exposed conductive parts, and installed more than 2.5 m (8 ft) from exposed grounded conductive parts or ground shall not be required to comply with 690.12(B)(2).
The requirement of 690.12(B)(2) shall become effective January 1, 2019.