Solar DC Combiner Box Inspection Checklist [FREE PDF]

DC combiner boxes aggregate multiple PV string circuits and represent one of the highest-risk electrical components in a solar installation. NEC Article 690 and IEC 62446-1 mandate regular inspection of overcurrent protection, disconnect means, and wiring integrity to prevent arc faults and ground faults. This checklist guides Solar Technicians through a structured inspection aligned with NFPA 70E shock and arc-flash hazard requirements.

Industry: Solar Energy
Frequency: Quarterly
Estimated Time: 30-45 minutes
Role: Solar Technician
Total Items: 37
Compliance: NEC Article 690 (NFPA 70-2023) - Solar Photovoltaic Systems, IEC 62446-1:2016 - PV Systems: Requirements for Testing and Documentation, NFPA 70E-2021 Article 130 - Energized Electrical Work, OSHA 29 CFR 1926.960 - Working on or Near Exposed Energized Parts, ANSI/NETA MTS-2019 - Maintenance Testing Specifications

PPE & Lockout/Tagout Verification

Confirm all personal protective equipment and energy isolation procedures are in place before opening the combiner box.

Has an arc-flash hazard analysis been completed and posted for this combiner box?
Is the inspector wearing appropriate arc-rated PPE matching the calculated incident energy level?
Has a lockout/tagout procedure been applied to all energy sources feeding this combiner box?
Is insulated tooling rated for the system DC voltage being used for this inspection?
Has a second qualified person been notified of the energized work location per site safety plan?

Enclosure Exterior Inspection

Inspect the physical condition of the combiner box enclosure, labeling, and mounting prior to opening.

Is the enclosure free from physical damage such as dents, cracks, or corrosion?
Is the enclosure NEMA/IP rating label legible and appropriate for the installation environment?
Are all required NEC 690 warning labels present, legible, and correctly positioned?
Is the enclosure mounting secure with no loose fasteners or sagging from the support structure?
Please photograph the exterior of the combiner box enclosure showing all labels?

Interior Wiring & Terminal Inspection

Examine wiring, cable management, terminal connections, and conductor condition inside the enclosure.

Are all DC string conductors properly identified and routed without crossing or stress points?
Are all wire terminations tight with no signs of overheating, discoloration, or arcing damage?
Is conductor insulation intact with no cuts, abrasion, or UV degradation visible?
Are conductors properly de-rated for conduit fill and ambient temperature per NEC 310?
Is cable management (clamps, tie-wraps, conduit entries) secure and free from sharp edges?
Are all unused conduit knockouts sealed with listed fittings?

Overcurrent Protection Devices

Inspect fuses and circuit breakers for correct ratings, condition, and proper installation.

Are all string fuses present and correctly rated per the system design documentation?
Are fuses and fuse holders free from corrosion, discoloration, or visible damage?
Do all fuses have a DC voltage rating equal to or greater than the maximum system DC voltage?
Is the main DC output breaker or fuse functional with no evidence of tripping damage or arc marks?
Record the measured DC string fuse resistance (mΩ) for the highest-resistance fuse found?

DC Disconnect & Surge Protection Devices

Verify DC disconnect switch operation and surge protective device (SPD) status.

Is the DC disconnect switch accessible, properly labeled, and operable without obstruction?
Does the DC disconnect switch open all current-carrying conductors including the grounded conductor where applicable?
Is a listed DC surge protective device (SPD) installed and showing a healthy status indicator?
Are SPD ground conductors sized and routed with minimum bends per manufacturer specification?
Please photograph the DC disconnect and SPD assembly showing all status indicators?

Grounding & Bonding

Inspect equipment grounding conductors, bonding connections, and ground fault detection systems.

Is the equipment grounding conductor (EGC) properly sized, connected, and continuous to the grounding electrode?
Are all metallic enclosure parts bonded to the EGC with listed bonding hardware?
Is the ground fault protection device (GFPD) present, functional, and properly tested?
Record the measured ground bond resistance between the enclosure and grounding electrode conductor?
Are grounding conductor terminations tight, corrosion-free, and using listed lugs?

Performance Monitoring & Documentation

Record electrical measurements, verify monitoring system connectivity, and complete documentation requirements.

Record the DC open-circuit voltage (Voc) measured at the combiner output today?
Is the string monitoring or data logger system communicating correctly and logging data?
Have all corrective actions from the previous inspection report been completed and verified?
Were any deficiencies or non-conformances identified during this inspection?
Please provide a detailed description of all deficiencies found and recommended corrective actions?
Has the completed inspection record been signed, dated, and filed in the site O&M logbook?

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Why Use This Solar DC Combiner Box Inspection Checklist [FREE PDF]?

This solar dc combiner box inspection checklist [free pdf] helps solar energy teams maintain compliance and operational excellence. Designed for solar technician professionals, this checklist covers 37 critical inspection points across 7 sections. Recommended frequency: quarterly.

Ensures compliance with NEC Article 690 (NFPA 70-2023) - Solar Photovoltaic Systems, IEC 62446-1:2016 - PV Systems: Requirements for Testing and Documentation, NFPA 70E-2021 Article 130 - Energized Electrical Work, OSHA 29 CFR 1926.960 - Working on or Near Exposed Energized Parts, ANSI/NETA MTS-2019 - Maintenance Testing Specifications. Regulatory-aligned for audit readiness and inspection documentation.

Frequently Asked Questions

What does the Solar DC Combiner Box Inspection Checklist [FREE PDF] cover?

This checklist covers 37 inspection items across 7 sections: PPE & Lockout/Tagout Verification, Enclosure Exterior Inspection, Interior Wiring & Terminal Inspection, Overcurrent Protection Devices, DC Disconnect & Surge Protection Devices, Grounding & Bonding, Performance Monitoring & Documentation. It is designed for solar energy operations and compliance.

How often should this checklist be completed?

This checklist should be completed quarterly. Each completion takes approximately 30-45 minutes.

Who should use this Solar DC Combiner Box Inspection Checklist [FREE PDF]?

This checklist is designed for Solar Technician professionals in the solar energy industry. It can be used for self-assessments, team audits, and regulatory compliance documentation.

Can I download this checklist as a PDF?

Yes, this checklist is available as a free PDF download. You can also use it digitally in the POPProbe mobile app for real-time data capture, photo documentation, and automatic reporting.