A solar plan can label every green conductor as ground and still leave the installer without a complete fault path. The problem starts when bonding, equipment grounding, and the grounding electrode connection collapse into one generic note. Review becomes harder because the single-line diagram, array detail, and conductor schedule appear to describe different systems.
Direct answer. Bonding joins exposed conductive parts into a continuous path. Grounding connects a circuit or equipment to earth, directly or through the grounding system. A solar plan set should show both as coordinated design decisions. The drawings must identify the bonded metal, equipment grounding conductor, grounding electrode connection, listed attachment method, and verification source.
This guide explains how those decisions should reconcile across a United States solar permit package. It does not prescribe conductor sizes or replace the adopted electrical code. The authority having jurisdiction, equipment instructions, and qualified electrical reviewer control each project.
What is the difference between grounding and bonding?
Bonding creates electrical continuity between conductive parts. Grounding connects a circuit or equipment to earth, or to a conductive body serving in place of earth. The words describe related actions, but they do not describe the same design decision.
The public federal definitions in 29 CFR 1910.399 make the distinction clear. Bonding permanently joins metallic parts into an electrically conductive path. That path maintains continuity and carries current likely to be imposed. The regulation defines grounded as connected to earth or a conducting body that serves in place of earth.
Those definitions are useful because they are openly accessible. They are Occupational Safety and Health Administration definitions, not quotations from the National Electrical Code. Project teams should use the adopted code and local amendments for design decisions.
In a photovoltaic array, bonding may connect module frames, rails, metallic raceways, junction boxes, and equipment enclosures. A listed clamp, bonding jumper, washer, or integrated racking feature may form part of that path. The exact method depends on the evaluated equipment combination and manufacturer instructions.
The equipment grounding conductor, or EGC, connects exposed metal equipment and raceways back through the grounding path. The EGC definition is useful, but a definition does not size or route the conductor. The plan set still needs project-specific information.
The grounding electrode conductor, or GEC, connects the grounding electrode system to designated system points. It is not another name for the module bonding path. A grounded conductor is also different because it is an intentionally grounded current-carrying circuit conductor.
These distinctions matter during fault diagnosis. The transformerless inverter DC ground-fault guide separates equipment bonding from insulation alarms and model-specific test procedures.
That gives the design team four separate questions:
- Which exposed conductive parts must be bonded together?
- How does the EGC return from each circuit and equipment location?
- How does the installation connect to the grounding electrode system?
- Does the system include a grounded current-carrying conductor?
Lightning protection is a fifth question. It can interact with array metal and electrode coordination, but it is not a substitute for electrical bonding. A generic lightning note cannot complete the fault-current path shown on an electrical plan.
Why must grounding and bonding appear across the solar plan set?
No single sheet can communicate the entire path. The array layout shows physical relationships. The single-line diagram shows electrical relationships. Details identify attachment methods, while schedules identify conductor information. Equipment notes connect those decisions to evaluated products and instructions.
The City of San Diego provides a useful current example in Information Bulletin 301. Its 2026 bulletin requires a site plan and single-line diagram with relevant system equipment. It also requests manufacturer installation specifications where applicable.
San Diego rules do not govern every United States project. The example still shows why electrical information must travel across several documents. A module bonding method can be correct on a detail and absent from the equipment submission. An EGC can appear on the diagram but disagree with the conductor schedule.
Treat grounding and bonding as a connected data set. Each sheet should answer one part of the installation question. Every repeated value should match its source.
The solar permit package checklist covers the larger submission. Grounding coordination is narrower. It begins after equipment selection and continues through final drawing quality control.
Which sheets should show each grounding and bonding decision?
Use the following matrix before an electrical quality review. It assigns each decision to a primary sheet and shows where supporting information should appear. The final sheet names depend on the project template and jurisdiction.
| Design decision | Primary location | Supporting location | Verification source | Common conflict |
|---|---|---|---|---|
| Bonded module frames and rails | Array grounding detail | Layout and equipment notes | Racking and module instructions | Detail shows hardware that the bill of materials omits |
| Listed bonding attachment | Grounding detail | Equipment schedule | Listing and installation instructions | Clamp is listed for another rail or module combination |
| Equipment grounding conductor path | SLD or 3LD | Conductor schedule and details | Adopted code and equipment instructions | Diagram and schedule show different conductors |
| Raceways and enclosures | SLD or 3LD | Equipment notes | Raceway and enclosure instructions | Bonding point disappears at a transition |
| Grounding electrode connection | SLD or 3LD | Site plan and grounding detail | Existing conditions and adopted code | New electrode appears isolated from the existing system |
| Existing grounding electrode system | Site plan | SLD or 3LD | Field survey and record drawings | Existing condition is assumed but not verified |
| Grounded circuit conductor | SLD or 3LD | Conductor schedule | System architecture and equipment instructions | Neutral and EGC are treated as interchangeable |
| Bonding across movable or separated parts | Detail | Layout and equipment note | Product instructions | Hinges, splices, or sections interrupt continuity |
| Carport or ground-mount steel | Site plan and structural layout | Grounding detail | Structural layout and electrical design | Electrical and structural sheets use different post identifiers |
| Inspection or test note | General electrical notes | Grounding detail | Project quality plan | Note asks for a test without defining its basis |
The matrix is a coordination aid, not a universal permit checklist. A local form may require another location, label, or document. Confirm the required content before drafting the final package.
The most important column is verification source. Every drawing statement should trace to a field condition, adopted requirement, product instruction, or approved design decision. A copied note without a source can survive several reviews before failing in the field.
What belongs on the single-line or three-line diagram?
The single-line diagram, or SLD, should show the grounding path as part of the electrical system. Do not place one ground symbol beside the service and assume the symbol explains the entire installation.
At minimum, the designer should evaluate whether the diagram needs to identify:
- The EGC along each relevant circuit segment.
- Metallic raceway treatment and transitions.
- Equipment enclosures and disconnects in the path.
- The grounding electrode system connection point.
- Existing and proposed electrodes when project scope changes them.
- Grounded conductors, when present, without merging them with the EGC.
- Bonding jumpers at locations where continuity needs an explicit method.
- Notes directing readers to the grounding and bonding details.
A three-line diagram can show phase, neutral, and grounding relationships more explicitly. The choice between an SLD and 3LD depends on the project, utility, and review requirements. The drawing type does not remove the need for coordination.
Use stable equipment identifiers. If the inverter is INV-1 on the layout, the same identifier should appear on the diagram and equipment schedule. The grounding detail should use that identifier when the attachment depends on the enclosure or raceway.
The conductor schedule must agree with the diagram. Compare conductor function, material, insulation, routing, and applicable sizing basis. Avoid adding a conductor tag whose only explanation appears in a detached calculation file.
The diagram should also show scope boundaries. Existing conditions need an existing label. Proposed conductors and electrodes need proposed labels. Field verification notes should identify what must be confirmed before construction.
Our guide to solar SLD software explains drawing production tools. Software can keep symbols and schedules organized. It cannot decide whether a project-specific bonding path is complete.
What belongs on the array layout and grounding detail?
The layout establishes where conductive parts meet, separate, and transition. The grounding detail then explains how the intended continuity is created. These sheets should use the same module, rail, attachment, and equipment identifiers.
Start with the full array boundary. Show module groups, racking segments, roof areas, carport bays, or ground-mount tables. Identify equipment that interrupts or changes the path. Examples include expansion joints, rail splices, junction boxes, and transitions into raceway.
The grounding detail should answer practical installation questions:
- What hardware bonds the module frame to the support system?
- Does the path continue across every rail splice and structural break?
- Where does the EGC attach to the racking or equipment?
- Which attachment points require surface preparation or specific torque?
- Which parts may not accept field drilling or substituted hardware?
- Where do conductor material transitions require compatible components?
- Which instruction governs each attachment?
Do not invent universal answers in the detail. Use the selected equipment instructions. A plan note such as bond all modules per code provides no attachment method, component, or traceable reference.
The module frame bonding glossary explains the concept. The drawing must go further. It should identify the actual listed method for the selected module and racking combination.
Use an enlarged detail when the assembly cannot be read at plan scale. Show the connection location and the relevant parts. Avoid decorative detail drawings that omit hardware identifiers.
If a repeated connection is typical, define the limits of typical. A rooftop array may include different rail families, module types, or attachment zones. One detail should not silently govern incompatible assemblies.
How should listed racking and module bonding be documented?
Document the evaluated combination, not only the standard name. The plan set should connect the selected module, racking system, bonding device, and installation instruction to the same assembly.
The public UL 2703 scope covers photovoltaic mounting systems and related grounding or bonding devices. It also addresses clamping or retention devices for specified modules. The public page shows a revision dated April 28, 2026.
That scope supports a useful drawing rule. A UL 2703 reference alone does not prove that every module, rail, clamp, and configuration works together. The equipment submittal should identify the evaluated combination and its installation conditions.
Build a short verification record before detailing:
- Record the module manufacturer and exact model.
- Record the racking family and relevant component numbers.
- Identify the bonding or grounding device for that combination.
- Save the applicable instruction revision.
- Mark the pages supporting the proposed configuration.
- Transfer required installation conditions into the detail.
- Check the bill of materials against the drawing callouts.
Watch for substitutions. A module can fit a clamp mechanically while falling outside the documented combination. A rail revision can change the bonding method. The drawing and procurement record should share the same equipment identity.
The designer should also separate bonding hardware from ordinary attachment hardware. A fastener that restrains a module does not automatically establish the intended electrical path. The product documentation must support the claimed function.
If the selected assembly uses integrated bonding, label that method clearly. If a jumper is required at a splice or transition, show the jumper. Do not rely on a field installer to discover a missing connection from multiple manuals.
How do the EGC, GEC, and electrode system work together?
The EGC, GEC, and grounding electrode system serve connected but distinct functions. The plan set should name each function and show where their paths meet. Generic ground wire labels make this review difficult.
An equipment grounding conductor connects exposed metal equipment, raceways, and enclosures through the equipment grounding path. The grounding electrode conductor connects the grounding electrode to designated system points. The electrode system provides the earth connection required by the project design.
The federal definitions in 29 CFR 1910.399 distinguish these conductors. They do not provide project sizing or installation instructions. Use the adopted code, local amendments, and project conditions for those decisions.
Show these relationships in a logical sequence:
- Trace the EGC from array equipment through every circuit segment.
- Identify changes in conductor or raceway method.
- Show bonding at enclosures, raceways, and exposed metal assemblies.
- Identify the grounding electrode system connection point.
- Label existing and proposed portions of the electrode system.
- Reconcile each conductor tag with the schedule and calculations.
Do not present a separate array ground rod as a universal solution. A local electrode may have a project role, but it does not automatically replace the required equipment grounding path. Its connection to the wider grounding electrode system needs deliberate review.
Do not merge neutral and grounding functions in a diagram without a supported system reason. Their relationship changes across equipment and service boundaries. The diagram should make the selected architecture reviewable.
The equipotential bonding glossary explains why connected metal should remain at a common potential. In a plan set, that concept becomes a series of identified physical connections. Each connection needs a method and a location.
What changes for rooftop, carport, and ground-mount projects?
The electrical concepts remain related, but the physical continuity problems change by mounting type. The plan set should respond to those physical conditions instead of reusing one standard detail.
Rooftop arrays
Rooftop coordination usually focuses on module frames, rails, roof-mounted enclosures, and raceway transitions. Multiple roof planes can create separate racking groups. Expansion joints and row breaks may interrupt an assumed path.
The layout should show where conductors leave the array and enter raceway. Details should identify the selected module and racking combination. Roof work also needs coordination with structural and waterproofing details.
Solar carports
Carports combine electrical equipment with large structural steel assemblies. The structural plan and electrical plan must use matching column, beam, and equipment identifiers. Bay separations, hinged elements, and detached canopies deserve explicit review.
Do not assume that every bolted structural connection provides the intended electrical continuity. The electrical design should identify its bonding method. The structural team should review any detail that changes steelwork or protective coatings.
Ground-mount arrays
Ground-mount projects introduce long table rows, fence interfaces, combiner locations, and equipment pads. The site plan becomes important because it shows separation between array blocks and central equipment.
Long distances also increase the chance that a schedule, diagram, and layout use different route assumptions. Trace every transition from table to trench, enclosure, inverter, and interconnection equipment.
Lightning exposure can receive more attention on open sites. Keep lightning protection coordination separate from normal grounding and bonding decisions. Engage the appropriate specialist when the project scope includes a lightning protection system.
| Project type | Primary continuity question | Sheet that often reveals the conflict |
|---|---|---|
| Rooftop | Do separate rows and roof planes share the documented path? | Array layout |
| Carport | Do structural and electrical identifiers describe the same steel assembly? | Structural layout and grounding detail |
| Ground mount | Does each table and equipment transition connect to the intended path? | Site plan and SLD or 3LD |
What does complete coordination look like on one project?
Consider an illustrative commercial rooftop project with three array areas and two inverter locations. The modules use a racking system with integrated bonding at approved clamps. Metallic raceway connects roof-mounted junction boxes to electrical equipment below.
This example does not establish a code-compliant design. It shows how one verified decision should propagate through the drawing package.
Step 1: Record the equipment basis
The designer records each module model, rail family, clamp, splice, and bonding accessory. The record includes the applicable instruction revision and supported configuration. Procurement identifiers match the drawing equipment schedule.
This step prevents a later drawing from naming only generic bonded racking. It also gives the quality reviewer a defined combination to check.
Step 2: Divide the layout into electrical assemblies
The roof plan labels the three array areas as A1, A2, and A3. It also labels both junction boxes and both inverters. Separate roof planes and rail groups remain visible.
Each array area receives a detail reference. The reference tells the installer which bonding detail applies. A general note identifies any conditions requiring field verification.
Step 3: Show the path on the diagram
The SLD traces the EGC through each circuit segment. Junction boxes, raceway transitions, inverters, and the grounding electrode connection use the same identifiers as the roof plan.
The diagram does not draw every module clamp. It points to the array bonding detail for that repeated connection. This keeps the diagram legible without hiding the attachment method.
Step 4: Detail every change in continuity method
The standard module-to-rail detail covers the supported integrated bonding method. A separate rail-splice detail applies where the product instructions require it. Another detail covers the EGC attachment to each array assembly.
The detail titles name their limits. They do not use one typical label for unrelated conditions. Every called-out accessory appears in the bill of materials.
Step 5: Reconcile the schedule
The conductor schedule uses the same circuit and equipment identifiers. It distinguishes current-carrying conductors, the EGC, and any GEC shown on the diagram. Existing and proposed conductors remain visibly separate.
The reviewer compares the schedule with the SLD one segment at a time. Any missing segment becomes a drawing issue before submission.
Step 6: Test a late substitution
Assume procurement proposes a different module after the first drawing issue. The project team does not update only the module schedule. It reopens the supported racking combination, clamp conditions, array detail, and bill of materials.
If the revised module remains supported, the evidence record captures that result. If it requires another attachment, every dependent drawing receives the change. This is the purpose of the coordination matrix.
The same method works for a changed inverter location or raceway route. Identify the changed input, reopen each dependency, and retain the closeout record. That process is more reliable than searching for old model numbers after redlines arrive.
Which conflicts should an electrical QA pass catch?
The final quality check should compare sheets against each other, not review each sheet alone. A perfectly drafted detail can still conflict with the equipment schedule or diagram.
Run the check in a fixed order:
- Equipment identity. Match module, racking, inverter, enclosure, and accessory identifiers.
- Path continuity. Trace bonded metal and the EGC from the array to the designated system point.
- Conductor agreement. Compare every EGC and GEC tag with the conductor schedule.
- Electrode scope. Confirm existing and proposed electrodes are clearly separated.
- Attachment method. Match each bonding device to the documented equipment combination.
- Transition review. Inspect rail splices, raceway changes, detached structures, and equipment boundaries.
- Note review. Remove copied notes that conflict with the selected equipment or jurisdiction.
- Document revision. Confirm the cited instruction revision is retained with the package.
- Jurisdiction review. Confirm the adopted code edition and local amendments.
- Field assumption review. Mark conditions that require verification before construction.
The NFPA 70 development page identifies NFPA 70 as the National Electrical Code. It does not tell a designer which edition a jurisdiction enforces. Use NFPA CodeFinder as a starting point, then confirm the result with the authority.
Check one more failure mode before issue. Search the plan set for ground, grounded, grounding, bond, bonding, EGC, GEC, and electrode. Review every occurrence in context. The same term should not carry different meanings across sheets.
The broader commercial solar electrical design checklist can follow this focused review. That checklist also covers interconnection, protection, diagrams, and labels.
What should designers avoid copying from old solar plans?
Old plan notes can provide drafting structure, but they are weak technical evidence. Equipment combinations, code editions, local amendments, and field conditions change. Copy only after revalidating each statement.
The City of San Diego hosts a legacy residential photovoltaic plan template. It shows how older plan sets distributed frame, equipment, EGC, and electrode information. It should not supply current section references, minimum sizes, or universal details.
Remove these high-risk note patterns:
- Fixed conductor sizes without a documented project basis.
- Universal resistance targets without jurisdiction and method support.
- Statements that a ground rod replaces an equipment grounding path.
- Bond all metal notes without component or attachment identification.
- Manufacturer requirements that name no manufacturer or document.
- Current code claims copied from an unknown edition.
- Acceptance statements attributed to all inspectors or all utilities.
- Lightning language presented as ordinary bonding compliance.
A copied note often looks authoritative because it includes a section number. That appearance is not evidence. Confirm the adopted edition and read the applicable project documents before retaining the note.
How can the plan set stay coordinated during revisions?
Manage grounding and bonding information as controlled project data. A late module, racking, inverter, or route change should trigger a bounded coordination review. Do not wait for a full redline cycle.
Create a change table with five fields:
| Changed input | Sheets to reopen | Evidence to reopen | Coordination owner | Closeout record |
|---|---|---|---|---|
| Module model | Layout, grounding detail, equipment schedule | Module and racking instructions | Electrical designer | Approved equipment match |
| Racking family | Layout, detail, bill of materials | UL scope and product instructions | Electrical and structural designers | Revised detail |
| Inverter location | Site plan, SLD or 3LD, schedule | Route and equipment instructions | Electrical designer | Updated conductor path |
| Raceway method | SLD or 3LD, detail, schedule | Raceway and equipment documents | Electrical designer | Transition review |
| Electrode scope | Site plan, diagram, detail | Field survey and adopted requirements | Qualified reviewer | Verified existing condition |
Use revision clouds to show the changed result, but do not treat clouds as coordination. The owner must reopen every dependent sheet and evidence record. A change log makes that action visible.
Before resubmission, compare the response letter with the revised drawings. The AHJ submission guide explains that wider workflow. Every response should point to the exact sheet and revision that closes the comment.
How does Heaven Designs support grounding and bonding coordination?
Heaven Designs can prepare and coordinate solar permit drawings within an agreed project scope. The work can include layouts, electrical diagrams, schedules, equipment notes, and drawing revisions. Project inputs and review responsibilities should be defined before drafting begins.
Our solar permit design service focuses on drawing production and package coordination. You can also review sample design deliverables before defining the requested output.
Grounding and bonding decisions remain project specific. A qualified electrical professional should confirm conductor decisions, adopted-code requirements, equipment instructions, and local amendments. Heaven Designs does not promise approval or replace the authority’s review.
If your team needs a coordinated plan-set scope, send the project details. Include the jurisdiction, code basis, equipment schedule, site information, existing electrical records, and required deliverables.
Frequently asked questions
Is bonding the same as equipment grounding?
No. Bonding joins conductive parts to form electrical continuity. Equipment grounding connects exposed metal equipment and raceways into the grounding path. A plan set often shows both because bonded module and racking assemblies connect into the equipment grounding system.
Does every solar array need a separate ground rod?
Do not assume that it does. Electrode requirements depend on the adopted code, local amendments, system architecture, and project conditions. A separate electrode also does not automatically replace the equipment grounding path. Show the selected design and its connection to the wider system.
Can racking hardware provide module bonding?
Some evaluated racking assemblies use integrated bonding hardware. The exact module, rack, clamp, configuration, and installation conditions still matter. Verify the selected combination against current product instructions and listing information before showing it on the detail.
Where should the EGC appear on a solar plan?
Show the EGC on the SLD or 3LD and reconcile it with the conductor schedule. Supporting details should show attachment and transition information where needed. The array layout can identify physical routes or equipment locations that affect continuity.
Should the plan cite one NEC edition for every project?
No. Adoption varies by jurisdiction and can include local amendments. Confirm the applicable edition for the project location. Use NFPA CodeFinder as a research aid, then verify the result with the authority having jurisdiction.
Is lightning protection part of the grounding detail?
It may require coordination with grounding and conductive structures, but it is a distinct design subject. Do not use lightning notes as a substitute for the electrical bonding path. Engage the appropriate specialist when the project includes a lightning protection system.
Final review note
This article explains a coordination method, not a complete electrical design. Before publication or project use, a qualified electrical reviewer should confirm the adopted edition, local amendments, equipment instructions, and every project-specific connection.