Listed equipment is equipment that appears on a list published by an evaluation organization. That organization periodically inspects production and states that the item meets identified standards or is suitable for a stated purpose. In the codes, the word listed generally means the product was evaluated to the appropriate standards by an independent third-party certifier, such as a nationally recognized testing laboratory (NRTL). Do not confuse the code term listed with the UL marks: UL Listed covers all reasonably foreseeable safety hazards, while UL Classified covers only a limited range of hazards or conditions of use. The NEC requires PV equipment such as inverters, modules, combiners, dc-to-dc converters, rapid shutdown equipment and charge controllers to be listed, or to be field-evaluated and carry a field label. Testing laboratories do not issue letters confirming a listing, so the Listing Mark on the product is the best way to check it. A listing may cover a whole system only when it is installed as specified. For example, a UL 3741 PV hazard control system counts as listed only when the required components are installed per the manufacturer's instructions. A storage unit's listing may include the vendor-supplied harnesses and wire management. For utility interconnection, certified equipment such as UL 1741 or UL 1741 SA inverters speeds up the review. Equipment that is not listed may need witness tests, such as synchronization and harmonics tests.
<!-- review notes
related_toc1 verified · fact Eversource CT Yellow Book proposed
The definition adds that the listing organization periodically inspects production and that the listing states the item meets identified standards or was tested and found suitable for a purpose.
sec=h40 h=cf7380980910verified by: review-workflowverified on: 2026-10-24
UL is an example of an independent third-party certifier. In UL terms, 'UL Listed' means evaluated for all reasonably foreseeable safety hazards, and 'UL Classified' means evaluated for a limited range of hazards or conditions. Neither is the same as the code term 'listed'.
sec=h8 h=eb2e5b212940c3 drafted · lead UL 1741 proposed
FirstEnergy requires witness testing, such as synchronization and harmonics tests, for interconnection equipment that is not listed to UL 1741.
tbl=1.r4 h=2ba925e11b1btbl=1.r11 h=e98bb96dd03bc4 drafted · lead UL 1741 SA proposed
HECO qualified equipment lists include advanced inverters certified to UL 1741 SA. A Tesla storage system is stated to be NRTL listed to UL 1741 SA.
tbl=5.r2 h=2dfed7267830sec=h2 h=186d01479519sec=h2 h=3801d4d2bd0areview note: support check: partial - Tesla NRTL listed to UL 1741 SA is stated, and the HECO list certifies advanced inverters to UL-1741 SA; the passages say 'certified', not 'listed', and the qualified list is called approved rather than described as listed equipment.
c5 drafted · lead UL 3741 proposed
PV hazard control equipment can be listed to UL 3741. A listed PV hazard control system is only established when the required equipment is installed per the manufacturer's instructions.
sec=front h=17adc1e81ee5sec=h49 h=75726c627db4c6 drafted · lead UL 1642 proposed
Lithium-ion cells in a Tesla storage product are stated to be NRTL listed to UL 1642.
tbl=5.r1 h=e4caf933969ctbl=5 h=52e1602fef91c7 drafted · lead UL 1973 proposed
tbl=5.r2 h=2dfed7267830tbl=5 h=52e1602fef91c8 drafted · lead UL 9540 proposed
tbl=5.r2 h=2dfed7267830tbl=5 h=52e1602fef91c9 drafted · lead Interconnection process
The utility reviews certified generator equipment packages in less detail, so review is faster and costs less.
sec=h48 h=7148d2ac6129c10 drafted · lead Equipment grounding
Listed devices such as WEEBs may be used for grounding.
sec=h108 h=0b3e42fc6d88c11 drafted · lead PV hazard control
sec=front h=17adc1e81ee5sec=h49 h=75726c627db4related_to c3related_to c5related_to c6