DC Disconnect Switch for Solar: NEC 690.13 Compliance Checklist 2025

dc disconnect switch for solar represent mandatory safety components in solar photovoltaic installations, governed by strict NEC requirements under Article 690.13. Understanding these code requirements ensures compliant installations that protect both personnel and equipment while satisfying inspection authorities. This comprehensive guide covers every aspect of NEC 690.13 compliance for DC disconnect switches in solar applications.

Proper disconnect switch selection and installation goes beyond simply mounting a switch near the inverter. Code compliance requires attention to ratings, placement, labeling, grouping, and accessibility that many installers overlook until inspection failures force costly rework.

Understanding NEC 690.13 Requirements

Disconnecting Means Fundamentals

NEC Article 690.13 establishes the foundational requirement that all current-carrying conductors from photovoltaic systems must have disconnecting means to isolate the system for maintenance and emergencies. This requirement applies to both DC conductors from arrays and AC conductors feeding from inverters, though our focus here addresses the DC disconnect requirements specific to solar installations.

The code specifies that disconnecting means must disconnect all ungrounded conductors simultaneously. For typical solar systems with ungrounded positive and negative DC conductors, the disconnect must open both poles together in a single operation. Single-pole switches or disconnects that leave one conductor energized do not satisfy code requirements regardless of which conductor they interrupt.

Disconnecting means must be manually operated without requiring tools for normal operation. This ensures rapid disconnection during emergencies when personnel may lack specialized equipment. Lock-out/tag-out provisions allow securing disconnects in the open position during maintenance, preventing accidental re-energization while workers service equipment.

💡 Key Insight: The term “disconnecting means” in NEC 690.13 encompasses various device types—knife blade switches, circuit breakers, and specialty solar disconnects all qualify when meeting the specified requirements for ratings, accessibility, and labeling.

Required Disconnect Locations

NEC 690.13(E) specifies multiple required disconnecting means locations throughout solar photovoltaic systems. The PV system disconnect must be located at a readily accessible point, typically outside the building or at the point of entrance. This allows first responders to de-energize the system without entering structures during fire or other emergencies.

Array disconnects may be required on the roof or at array locations when conductors exceed specified lengths before reaching accessible disconnect locations. NEC 690.13(E)(1) requires accessible disconnects for all conductors within buildings, effectively mandating disconnects before conductors enter structures when arrays mount on roofs or separate buildings.

Equipment disconnects must be provided at the DC input of inverters and other equipment processing PV power. This allows servicing individual equipment without de-energizing entire systems. On large installations with multiple inverters, each inverter needs individual disconnecting means plus a main PV system disconnect controlling all DC sources.

Grounded vs Ungrounded System Requirements

Grounded PV systems—those with one current-carrying conductor intentionally connected to ground—require disconnects only in ungrounded conductors per NEC 690.13(A). Traditionally this meant only the positive conductor needed switching, though modern practice increasingly grounds the center point of strings requiring disconnection of both positive and negative conductors.

Ungrounded PV systems require simultaneous disconnection of all current-carrying conductors since no conductor connects to ground. Most contemporary utility-interactive solar installations use ungrounded configurations, mandating two-pole disconnects for typical positive/negative DC systems. This requirement significantly impacts disconnect switch selection since single-pole devices cannot comply.

The distinction between grounded and ungrounded systems affects ground fault protection requirements as well. Grounded systems need ground fault detection and interruption per NEC 690.41, while ungrounded systems need ground fault detection indicators but not necessarily interruption. These differing requirements influence overall system design including disconnect selection and placement.

dc disconnect switch for solar Rating Requirements

Voltage Rating Specifications

DC disconnect switches must carry voltage ratings equal to or exceeding the maximum system voltage under all operating conditions. NEC 690.7 defines maximum PV system voltage as the sum of rated open-circuit voltages of series-connected modules corrected for lowest expected ambient temperature. This value can significantly exceed standard operating voltages—a nominal 600V system may have maximum voltage approaching 750V in cold climates.

Voltage ratings must specifically address DC operation, not just AC service. AC voltage ratings do not translate directly to DC capability since alternating current naturally crosses zero twice per cycle, extinguishing arcs without the sustained arcing challenges of direct current. A 600V AC rated switch may handle only 300-400V DC safely due to DC arc interruption demands.

UL 98 and UL 508 provide testing standards for switches in DC service, establishing performance criteria including arc interruption, temperature limits, and endurance cycling. Disconnects listed to these standards at appropriate DC voltages provide code-compliant voltage ratings. IEC 60947-3 offers international standards covering similar requirements for DC switch applications.

Nominal System Voltage	Max Temp-Corrected VOC	Required Disconnect Rating	Standard Disconnect Options
400V DC	480V	600V DC minimum	600V DC switches
600V DC	720V	1000V DC minimum	1000V DC switches
1000V DC	1200V	1500V DC minimum	1500V DC switches
1500V DC	1800V	2000V DC minimum	Special 2000V switches

Current Rating and Interrupting Capacity

Current ratings for DC disconnect switches must equal or exceed 125% of the maximum available current from PV sources per NEC 690.8. Unlike overcurrent protective devices, disconnects need not factor in the 156% sizing requirement for fuses, but the 125% margin ensures disconnects handle full PV output without excessive heating or contact wear.

Interrupting rating represents the maximum current a switch can safely interrupt when opened under load. While disconnects in solar installations should normally be opened only when circuits are de-energized, faults or emergencies may require load-break operation. Specify disconnects with interrupting ratings appropriate for maximum available PV current including fault conditions.

Disconnect switches rated as “non-load break” cannot safely interrupt current and must only be operated when circuits are de-energized. These switches cost less but impose operational constraints—before opening the disconnect, other means must remove load current. Load-break rated switches cost more but allow opening under normal operating conditions, providing operational flexibility worth the premium in most applications.

⚠️ Important: Never operate non-load break disconnects under current flow. The sustained DC arc can weld contacts closed, damage switch internals, or create fire hazards. Load-break rated switches specifically designed for solar DC service provide safe operation under all conditions.

Accessibility and Placement Requirements

Readily Accessible Location Standards

NEC defines “readily accessible” as capable of being reached quickly for operation, renewal, or inspection without requiring those to whom ready access is requisite to climb over or remove obstacles or to resort to portable ladders. This seemingly simple definition carries significant implications for DC disconnect placement in solar installations.

Roof-mounted disconnects generally do not satisfy “readily accessible” requirements since reaching them requires ladders or climbing—portable equipment that violates the definition. Disconnects controlling conductors entering buildings must be accessible from grade level or through normal building access, not requiring special effort or equipment to reach.

Height limitations apply to readily accessible disconnects. NEC 404.8(A) limits switches to a maximum 6 feet 7 inches above the floor or working platform. Mounting disconnects higher than this exceeds “readily accessible” limits even when ladders aren’t required. Lower mounting heights—4 to 5 feet above grade—provide better accessibility for varied personnel heights and abilities.

The readily accessible requirement applies differently to various disconnect types. Equipment disconnects at inverters may be readily accessible from inside equipment rooms, while PV system disconnects must be readily accessible to first responders from outside the building. Understanding which disconnects need external accessibility prevents code violations during design.

Grouping Requirements

NEC 690.13(D) requires equipment disconnecting means for a PV system to be grouped with all other disconnecting means for the system. This grouping requirement ensures personnel can rapidly identify and operate all disconnects without searching multiple locations throughout a facility. Exception provisions allow some flexibility, but default practice groups all PV disconnects in one accessible location.

Permanently affixed plaques or directories identify grouped disconnects when the grouping isn’t obvious. Labels must identify each disconnect’s function using language like “PV System Disconnect,” “Array 1 Disconnect,” and “Inverter 1 Disconnect” rather than cryptic codes requiring documentation to interpret. Clear identification proves critical during emergencies when unfamiliar personnel must locate and operate disconnects quickly.

The grouping requirement applies to both DC and AC disconnects in the PV system. Installations must gather the DC disconnect controlling array output, equipment disconnects at inverters, and AC disconnects for inverter output in one location or provide clear identification showing their relationships. Scattering disconnects throughout a facility without clear grouping and identification violates code requirements.

Working Space and Clearances

NEC 110.26 establishes working space requirements around electrical equipment including disconnect switches. Minimum clear working space of 3 feet depth must be maintained in front of disconnects where examination, adjustment, servicing, or maintenance might be needed while energized. This space must be kept clear—storage, equipment, or obstacles violate working space requirements.

Working space width must equal the width of the disconnect or 30 inches, whichever is greater. Height requirements mandate working space extending from the floor to 6½ feet or the height of the equipment, whichever is greater. These dimensional requirements ensure adequate space for safe disconnect operation and emergency access by personnel and first responders.

Dedicated equipment space requirements under NEC 110.26(E) prohibit foreign systems like plumbing, ductwork, or communications equipment in the space above electrical equipment up to 6 feet above the floor or equipment height. This protects against leaks or other failures from foreign systems damaging electrical equipment and ensures clear space for emergency access.

Labeling and Marking Requirements

Required Warning Labels

NEC 690.13(B) mandates specific warning markings at disconnect locations identifying them as photovoltaic system disconnecting means. Labels must be permanently affixed and legible, using materials that withstand environmental exposure throughout the equipment lifespan. Temporary labels or markers that fade, peel, or become illegible do not satisfy code requirements.

Standard label text reads “PHOTOVOLTAIC SYSTEM DISCONNECT” or similar clear language identifying the disconnect’s function. Letter size must be at least 3/8 inch tall for clear visibility from normal working distances. Reflective or contrasting colors improve visibility—white letters on red backgrounds are traditional for disconnect identification, though code doesn’t mandate specific color schemes.

Multiple disconnects in grouped locations need individual labels identifying which circuits or equipment each controls. Generic “PV Disconnect” labels on multiple switches create confusion—specific labels reading “Array 1 Disconnect,” “Inverter 2 Disconnect,” etc. provide the clarity required for safe operation and maintenance. Label every disconnect including those in sequences where context might seem obvious.

🎯 Pro Tip: Include voltage and current ratings on disconnect labels beyond just identification. “PV SYSTEM DISCONNECT – 600V DC – 50A” provides complete information allowing verification that the disconnect matches system requirements without consulting documentation.

Arc Flash and Hazard Warnings

NEC 110.16 requires arc flash warning labels on electrical equipment where examination, adjustment, servicing, or maintenance might be performed while energized. Solar DC disconnects generally require these warnings since maintenance often occurs with arrays energized—PV arrays cannot be completely de-energized without covering all modules or waiting for darkness.

Arc flash labels must warn that equipment can be energized from both the load side (PV array) and line side (inverter). This two-source hazard proves particularly dangerous in solar installations since opening the disconnect doesn’t de-energize the array side of the switch. Appropriate labels might read “WARNING – ELECTRIC SHOCK HAZARD – TERMINALS ON BOTH LINE AND LOAD SIDES MAY BE ENERGIZED.”

NFPA 70E provides guidance on arc flash hazard analysis and appropriate warning label content. While full arc flash calculations may not be required for smaller residential systems, commercial and utility-scale installations need proper arc flash analysis with labels showing incident energy levels, boundary distances, and required personal protective equipment for work on energized parts.

System Voltage and Current Identification

Labels must identify maximum system voltage and available fault current at disconnect locations per NEC 690.53. This information proves critical for personnel performing maintenance or first responders evaluating electrical hazards. Voltage labels must show actual maximum system voltage including temperature correction factors, not just nominal ratings.

Current identification indicates maximum available current including short-circuit contributions. In solar applications, short-circuit current generally equals 125% of short-circuit current from all parallel-connected strings. This value helps personnel select appropriate test equipment, breakers, or other devices when troubleshooting or performing repairs.

Update labels when systems are modified or expanded. A disconnect originally serving a 10kW system at 400V DC requires new labels when arrays expand to 20kW or string configurations change maximum voltage. Maintaining accurate labels throughout system life ensures safety information remains current and reliable.

Equipment Grounding and Bonding

Disconnect Enclosure Grounding

Metal disconnect enclosures must be grounded per NEC 690.43 regardless of whether the PV system itself uses grounded or ungrounded configuration. Enclosure grounding protects against shock hazards from insulation failures that could energize metal parts. Size equipment grounding conductors per NEC 250.122 based on the rating of the overcurrent protective device protecting the circuit.

Ground the disconnect enclosure using a separate equipment grounding conductor run with the PV circuit conductors, or use the metallic conduit system as the equipment grounding means when properly installed per NEC 250.118. Bonding bushings and jumpers ensure electrical continuity where conduit enters enclosures, maintaining low-resistance ground paths even if connections loosen over time.

Do not rely on structural steel, building frames, or other conductive paths not specifically approved as equipment grounding conductors. NEC 250.136 prohibits using earth as the sole equipment grounding conductor—a dedicated copper or aluminum conductor provides the reliable ground path required for safety and code compliance.

Bonding Conductors Across Disconnects

When the PV system includes a grounded conductor, maintain the grounding connection through the disconnect per NEC 690.35. This often requires a separate terminal or bus bar in the disconnect enclosure bonding the grounded PV conductor continuously through the disconnect switch. Opening the disconnect isolates ungrounded conductors but maintains the ground reference.

Ungrounded PV systems don’t require grounded conductor bonding through disconnects since no conductor is intentionally grounded. However, equipment grounding must still be maintained. These systems need equipment grounding conductors sized and installed per NEC 250.122, creating a ground path for metal enclosures and equipment even though current-carrying conductors remain isolated from ground.

Bond all metal parts of disconnect assemblies together using bonding jumpers or inherent electrical connections. Painted surfaces, anodized finishes, or other non-conductive coatings must be scraped away at connection points to ensure reliable electrical contact. Thread-forming screws or star washers bite through coatings to establish bonding connections.

Common Installation Mistakes and Code Violations

❌ Insufficient Voltage Rating

Problem: Installing DC disconnect switches with voltage ratings below maximum system open-circuit voltage.

Common scenarios:
– Using 600V DC switches in systems with 720V temperature-corrected maximum voltage
– Assuming AC voltage ratings apply to DC service without verification
– Failing to calculate cold-temperature voltage correction factors per NEC 690.7

Correction: Calculate maximum system voltage per NEC 690.7(A) including lowest expected ambient temperature correction. Select disconnect switches with DC voltage ratings exceeding this calculated maximum by a safety margin. Verify the disconnect carries a DC voltage rating from recognized testing labs, not just an AC rating.

❌ Single-Pole Disconnect in Ungrounded System

Problem: Installing single-pole disconnects that interrupt only one conductor in ungrounded PV systems.

Common scenarios:
– Using single-pole switches in positive conductor only
– Believing negative conductor doesn’t need switching because it carries same potential as positive
– Cost-cutting by avoiding more expensive two-pole disconnects

Correction: Install simultaneous multi-pole disconnects that interrupt all ungrounded conductors in one operation per NEC 690.13(A). Ungrounded PV systems require two-pole (or more) disconnects that open both positive and negative conductors together. Single-pole disconnects violate code regardless of which conductor they interrupt.

❌ Inaccessible Disconnect Location

Problem: Mounting required disconnects in locations not readily accessible to personnel.

Common scenarios:
– Roof-mounted disconnects requiring ladders to reach
– Disconnects mounted above 6 feet 7 inches requiring step stools
– Disconnects blocked by equipment, storage, or other obstacles

Correction: Mount PV system disconnects in readily accessible locations per NEC definition—reachable without ladders, climbing, or removing obstacles. Ground-level outdoor locations or normal building entrances typically satisfy accessibility requirements. Maintain clear working space per NEC 110.26 around all disconnects.

❌ Inadequate or Missing Labels

Problem: Disconnects lack required identification, warning labels, or hazard markings.

Common scenarios:
– Unlabeled disconnect switches forcing guesswork about their function
– Missing “PHOTOVOLTAIC SYSTEM DISCONNECT” identification
– Lacking arc flash warnings or voltage/current identification

Correction: Label every disconnect with permanent, legible identification per NEC 690.13(B). Include function identification, voltage rating, current rating, and appropriate hazard warnings. Use label materials designed for outdoor service that won’t fade, peel, or become illegible over time. Update labels whenever systems are modified.

Inspection and Testing Procedures

Pre-Energization Verification

Before energizing new installations, verify disconnect compliance through systematic inspection. Check voltage and current ratings against calculated maximum system values, confirming adequate safety margins. Inspect mechanical operation—disconnect should operate smoothly through full travel with positive ON and OFF positions indicated clearly.

Verify all required labels are present, legible, and accurate. Check that warning labels address both line and load side energization hazards specific to PV applications. Confirm working space meets NEC 110.26 dimensional requirements with no storage or obstacles encroaching on required clearances.

Test disconnect interrupting capability by cycling under load if possible during commissioning. While not required by code, functional testing reveals mechanical problems, contact issues, or other defects before they cause failures. Document testing results as part of system commissioning records.

Ongoing Maintenance Requirements

Annual disconnect inspection should verify continued code compliance and functional condition. Check labels for fading, damage, or illegibility requiring replacement. Inspect enclosures for corrosion, physical damage, or mounting degradation. Verify working space remains clear of obstructions that may have accumulated since installation.

Cycle disconnects annually to verify mechanical operation remains smooth and positive. Sticky operation, excessive force requirements, or uncertain position indication suggest maintenance needs. Clean and lubricate disconnect mechanisms per manufacturer recommendations, though avoid over-lubrication that attracts dust and debris.

Verify tightness of all electrical connections including line terminals, load terminals, and ground connections. Thermal cycling naturally loosens connections over time—annual verification and re-torquing prevents connection failures. Use thermal imaging to identify hot spots indicating high-resistance connections requiring immediate attention.

⚠️ Important: Always test for voltage on both sides of open disconnects before performing maintenance. PV arrays remain energized even with disconnects open, creating shock hazards for personnel assuming disconnect opening eliminated all hazards.

Advanced Considerations

Rapid Shutdown Integration

NEC 690.12 rapid shutdown requirements mandate that conductors more than 1 foot from PV array and not within the array boundary be limited to 80V within 30 seconds of shutdown initiation. Many modern disconnect switches integrate rapid shutdown functionality, combining disconnection with module-level shutdown control.

Integrated rapid shutdown disconnects simplify installations by combining functions in one device. However, verify that the disconnect’s rapid shutdown performance meets NEC 690.12 requirements for the specific system configuration. Some products only control modules from certain manufacturers or require compatible inverters to function properly.

The disconnect activating rapid shutdown must itself remain readily accessible per NEC 690.13 requirements. Some designs place the rapid shutdown initiator at the service entrance while the actual disconnect mounts elsewhere—verify this arrangement satisfies both accessibility and grouping requirements before installation.

Multiple Array Systems

Large installations with multiple PV arrays require careful disconnect planning to satisfy grouping and identification requirements. Each array typically needs its own disconnect, plus a main system disconnect controlling all arrays simultaneously. NEC 690.13(D) grouping requirements apply to these multi-array systems.

Create clear labeling schemes identifying individual array disconnects and their relationship to the main system disconnect. Consider layouts like “MAIN PV SYSTEM DISCONNECT” alongside “ARRAY 1 DISCONNECT – ROOF A,” “ARRAY 2 DISCONNECT – ROOF B,” etc. Directory plaques showing all disconnect locations help when physical grouping proves impractical.

Coordinate disconnects at multiple voltage levels in systems using DC-DC converters or other voltage transformation. Input and output disconnects may operate at different voltages requiring different rating specifications. Label these clearly to prevent confusion during maintenance or emergencies.

Special Applications and Exceptions

Building-Integrated PV Systems

Building-integrated photovoltaic (BIPV) systems that form structural building elements face unique disconnect challenges. Roof tiles, facades, or glazing incorporating PV cells cannot be easily isolated or covered, creating permanent energization concerns. NEC 690.12 rapid shutdown becomes particularly important in BIPV applications where individual modules cannot be accessed for manual de-energization.

Design BIPV disconnect systems with special attention to emergency responder access and safety. Consider multiple disconnect locations allowing isolation of building sections independently. Provide clear marking showing which disconnects control which building areas, using floor plans or diagrams when verbal descriptions prove inadequate.

BIPV systems often integrate with building management systems for disconnect control and monitoring. Verify that any remote or automatic disconnect controls include manual override capabilities per NEC requirements—automated systems cannot replace manually operable disconnecting means accessible to first responders.

Portable and Mobile Systems

RV-mounted, trailer-mounted, or temporary event PV systems require portable disconnect solutions meeting the same NEC requirements as permanent installations. The disconnect must remain readily accessible, properly rated, and appropriately labeled despite the mobile nature of the installation. Marine-grade or weather-resistant disconnects suit these applications where rough handling and environmental exposure exceed typical fixed installations.

Mobile system disconnects benefit from lockable covers preventing tampering or accidental operation during transit. However, locks must not prevent rapid emergency access—some designs use breakaway seals or similar provisions allowing quick access while revealing if disconnects were operated. Balance security against emergency access requirements.

Consider disconnect placement relative to vehicle movements and parking configurations. Disconnects accessible from standard passenger side positions prove easier to reach than those requiring walking around vehicles or accessing areas blocked by adjacent parking. Mount disconnects at comfortable working heights for typical vehicle ground clearances.

High-Voltage DC Systems (>1500V)

Utility-scale installations increasingly operate at voltages exceeding 1500V DC, requiring specialized disconnect switches designed for these extreme voltages. Limited products exist in this voltage range—careful specification and verification of ratings becomes critical. NEC 690 applies equally at these voltages, but component availability may constrain design options.

High-voltage disconnects require enhanced safety features including interlocking mechanisms preventing opening under load, extended creepage distances preventing surface tracking, and robust arc interruption systems. Personnel working on high-voltage DC systems need specialized training beyond typical electrical qualifications—document training requirements and restrict access accordingly.

Consider redundant disconnect systems at high voltages to maintain safety even if individual disconnects fail. Series disconnects provide backup isolation if primary disconnects don’t interrupt reliably. While code doesn’t mandate redundancy, the severe consequences of disconnect failure at extreme voltages justify the additional cost and complexity.

Frequently Asked Questions

What is the main difference between DC disconnect requirements for grounded vs ungrounded solar systems?

Grounded PV systems require disconnects only in ungrounded conductors per NEC 690.13(A), potentially allowing single-pole disconnects in traditional positive-grounded configurations. Ungrounded systems must disconnect all current-carrying conductors simultaneously, requiring two-pole or multi-pole disconnects. Most modern utility-interactive systems use ungrounded configurations, mandating two-pole disconnects that open both positive and negative conductors together. The distinction affects disconnect selection and cost—multi-pole disconnects cost more but are necessary for code compliance in ungrounded systems.

Where exactly must the “readily accessible” disconnect be located per NEC 690.13?

NEC requires readily accessible disconnects at the building point of entrance when PV conductors enter structures, at equipment locations like inverters, and for the overall PV system per 690.13(E). “Readily accessible” means reachable without ladders, climbing, or removing obstacles—typically ground level outdoor locations or normal building entrances. Roof-mounted disconnects don’t satisfy this requirement. The PV system disconnect must be accessible to first responders from outside the building without entering the structure, allowing emergency de-energization during fires or other hazards.

Can I use a circuit breaker as the required DC disconnect switch?

Yes, DC-rated circuit breakers can serve as disconnecting means when they meet NEC 690.13 requirements including appropriate voltage and current ratings, ability to interrupt all ungrounded conductors simultaneously, and proper labeling. Circuit breakers offer advantages including overcurrent protection integrated with disconnection and reset capability after tripping. However, verify the breaker carries DC ratings at system voltage—AC-only breakers do not satisfy code requirements regardless of their current rating. UL 489 lists circuit breakers suitable for disconnecting means service.

What happens if my DC disconnect switch is not properly labeled?

Improperly labeled or unlabeled disconnects violate NEC 690.13(B) and typically fail electrical inspection, preventing system approval and energization. Beyond code compliance, inadequate labeling creates safety hazards during maintenance and emergencies when personnel cannot quickly identify disconnect functions. First responders may be unable to locate and operate unlabeled disconnects during fires, increasing danger to occupants and emergency personnel. Proper labels must be permanently affixed, legible, and include function identification plus appropriate hazard warnings about line and load side energization.

Do I need separate disconnect switches for each inverter in a multi-inverter system?

Yes, NEC 690.13(E)(2) requires equipment disconnecting means at each inverter or other equipment processing PV power. Each inverter needs its own disconnect allowing servicing that equipment without de-energizing other inverters or the entire PV system. Additionally, a main PV system disconnect must control all DC sources per 690.13(E)(3). Large systems might have array disconnects, individual inverter disconnects, and a main system disconnect—all must be grouped per 690.13(D) or clearly identified showing their locations and relationships.

How often should DC disconnect switches be tested and maintained?

Test disconnects during commissioning to verify proper operation before energizing systems. Annual inspections should cycle disconnects to verify mechanical function remains smooth and positive, check label legibility, verify working space clearances, and examine connections for tightness. Use thermal imaging to detect hot spots indicating high-resistance connections requiring immediate attention. More frequent inspection may be needed in harsh environments or after significant weather events. Document all testing and maintenance with dates, findings, and corrective actions taken.

What voltage rating do I need for a 1000V DC solar system?

Calculate maximum system voltage per NEC 690.7(A) by multiplying module VOC by the temperature correction factor for your lowest expected ambient temperature—this typically yields 1150-1200V for nominal 1000V systems. Select disconnects rated minimum 1200V DC, though 1500V DC switches provide better safety margin. Never use AC voltage ratings—a 600V AC disconnect may only handle 300-400V DC safely. Verify disconnects carry UL 98 or similar DC listing at the specified voltage, not just manufacturer claims. String voltage calculations must account for cold weather voltage rise potentially exceeding nominal ratings by 20% or more.

Related Resources

Comprehensive DC disconnect switch compliance requires understanding how disconnects integrate with other solar system protection and safety components.

Learn more about related requirements in our detailed guides:

– Solar DC Circuit Breakers – Alternative disconnecting means using circuit breaker technology
– DC Fuse Protection – Overcurrent protection working with disconnects
– DC Isolator Switch Technology – Complete disconnect switch specifications and selection
– PV Combiner Box Design – Integrating disconnects in combiner assemblies

Ready to ensure NEC 690.13 compliant DC disconnect installations? Our technical team at SYNODE provides project-specific guidance on disconnect selection, placement, and labeling for solar installations from residential to utility-scale. We help navigate code requirements ensuring reliable, compliant disconnecting means for safe PV system operation.

Contact our application engineers for disconnect specification assistance and code compliance verification for your solar projects.

Last Updated: October 2025
Author: SYNODE Technical Team
Reviewed by: Electrical Engineering Department