690.31(B) Identification and Grouping.

In the 2014 NEC, this practice of a common gutter containing multiple inverter output circuits will be a code violation unless a barrier is installed to separate the inverter output circuit conductors.
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In the 2014 NEC, this practice of a common gutter containing multiple inverter output circuits will be a code violation unless a barrier is installed to separate the inverter output circuit conductors.

Code Change Summary: New restrictions were added on the grouping and separation of specific PV system conductors.

The previous 2011 NEC® code language in 690.4(B) was simple. PV source circuits and PV output circuits could not be contained in the same raceway, cable tray, cable, outlet box, junction box, or similar fitting as conductors, feeders, or branch circuits of other non-PV systems, unless the conductors of the different systems were separated by a partition.

The 2014 NEC® has moved this same code language to 690.31(B) and added one very important adjustment. Now this rule also applies to inverter output circuits. This is an enormous code change for those installing multiple string inverters connected to a common gutter as in the image.

Before the code change, the rule only required PV source and PV output circuits to be kept separate from other non-PV system conductors. Now the rule even applies to other PV system inverter output circuits. This will mean installing partitions inside common gutter boxes where multiple string inverters are connected to supply their inverter output circuits.

Below is a preview of the NEC®.  See the actual NEC® text at NFPA.ORG for the complete code section. Once there, click on the “free access” tab and select the applicable year of NFPA 70 (National Electrical code).

2011 Code Language:

690.4 (B) Identification and Grouping. Photovoltaic source circuits and PV output circuits shall not be contained in the same raceway, cable tray, cable, outlet box, junction box, or similar fitting as conductors, feeders, or branch circuits of other non-PV systems, unless the conductors of the different systems are separated by a partition.

2014 Code Language:

690.31(B) Identification and Grouping. PV source circuits and PV output circuits shall not be contained in the same raceway, cable tray, cable, outlet box, junction box, or similar fitting as conductors, feeders, branch circuits of other non-PV systems, or inverter output circuits, unless the conductors of the different systems are separated by a partition.

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690.31(B) Identification and Grouping.

Below is a Real Question from our Electrical Continuing Education Courses for Electrical License Renewal:

Which of the following is true when several inverter output circuits share a common gutter box?

A: They must be separated from each other by a partition.
B: They are permitted to be installed in the same enclosure with no required separation.
C: They are permitted to share a common gutter box as non-PV system conductors without a partition.
D: The AC and DC conductors of each system must be grouped every 4 ft.
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