Keyur Rakholiya Equipotential bonding connects all exposed metal parts of a PV system, including module frames, racking, enclosures and raceways, so they stay at the same electrical potential. In the US, NEC 690.43 and Article 250 govern PV bonding, and IEC 60364-7-712 covers it internationally. It reduces shock risk during faults and limits surge damage.
Key Takeaways
- Equipotential bonding = all metal at same voltage.
- Prevents shock during faults.
- Reduces induced lightning damage.
- Required by NEC 690.43 + IS 3043.
- Verified during CEIG inspection in India.
Why It Matters on a Real Array
A solar array is mostly metal, aluminum racking, steel piles, module frames, conduit runs, combiner box enclosures. None of that metal is intentionally energized, but a ground fault inside a module, a damaged conductor, or a nearby lightning strike can momentarily push current through parts of it.
If the racking rail and the module frame bolted to it aren’t bonded to the same point, a fault on one can leave it at a different voltage than the other, even a few volts of difference is enough to create a shock path through anyone touching both at the same time.
Equipotential bonding removes that difference before it can appear. Every exposed metallic part, frames, rails, conduits, enclosures, is tied into a single low-impedance network and referenced to the equipment grounding conductor (EGC) described in Module Frame Bonding and EGC.
When a fault does occur, the whole network rises and falls together instead of splitting into isolated islands at different potentials, and the fault current has a clear low-impedance path back to the source so protective devices can trip.
The same bonded network also helps dissipate induced current from a lightning strike near a Lightning Protection System (LPS) rather than letting it arc between components, which is why bonding and surge protection are usually specified together rather than treated as separate line items.
Related Reading
Equipotential bonding sits alongside ground fault protection and SPD sizing as one of the three checks reviewers look for on the electrical drawing set before a plant is cleared to energize, a gap in any one of them tends to show up as a rework item during CEIG or AHJ review.
Bonding details for racking and piles are usually documented on the single-line and grounding drawings; our piece on Solar SLD Software walks through how NEC 2023-compliant single-line diagrams auto-generate the grounding and bonding annotations reviewers check for.
On ground-mount projects specifically, the bonding path runs from module frame to rail to pile, so the pile layout itself matters, see Pile Foundation Design for Solar Ground-Mount for how that structural layer is engineered.
Frequently Asked Questions
4 commonly searched questions about Equipotential Bonding.
What is the difference between bonding and grounding?
How are solar module frames bonded?
Does equipotential bonding protect against lightning?
What happens if bonding is missing on a PV array?
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