Grounding and Bonding PV Systems: Page 2 of 2

Intermediate
A bonding jumper
A bonding jumper connects two mounting rails to provide continuous grounding capability.
WEEB grounding washer
This WEEB grounding washer can be sandwiched between a module and its mounting rail. The protrusions bite into both, creating an approved ground path between them.
Grounding with a continuous copper wire
Traditionally, individual modules were grounded with a continuous copper wire.
Grounding lug
This grounding lug is commonly used to bond a grounding conductor to a mounting system.
A bonding jumper
WEEB grounding washer
Grounding with a continuous copper wire
Grounding lug

A new listing standard for bonding and grounding—UL2703—is one effort to eliminate this controversy and address Section 690.43(D) in the 2011 Code. The UL listing allows using mounting systems to provide the required grounding for module frames. Although the standard has not been finalized, multiple racking manufacturers are testing their systems to the draft standard and are offering products that have passed the draft. These products will save installation time and effort, since they eliminate the separate EGC connections.

The last two subsections of 690.43 help clarify the installation requirements. Subsection (E) allows listed devices to be used to bond modules mounted adjacent to each other. Subsection (F) requires that the EGCs for PV circuits run with the circuit conductors as they all leave the vicinity of the array. Although this contradicts the exception noted in 250.134(B), because they are PV circuits, the specific rule laid out in 690 takes precedence.

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Ryan Mayfield is the principal at Renewable Energy Associates, a design, consulting, and educational firm with a focus on PV systems. His latest personal PV project afforded him the opportunity to evaluate many nuances of grounding and bonding.

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