Disconnecting Means for PV Systems: A Guide to NEC 690.13 & 690.15

Understanding the requirements for solar PV disconnect means is critical for safety and code compliance. According to the National Electrical Code (NEC), there are two primary articles to master: NEC 690.13, which covers the main PV system disconnecting means, and NEC 690.15, for the equipment isolating device. The main disconnect, governed by 690.13, must be in a readily accessible location and have an interrupting rating sufficient for the available fault current. Its purpose is to de-energize the entire system from the building’s conductors. In contrast, NEC 690.15 mandates a separate isolating device for individual pieces of equipment like inverters. The 2023 NEC code book updated this section to use “in sight from” for placement of the isolating device; “in sight from” is defined in Article 100 as visible and not more than 15 m (50 ft) distant from the equipment. A proper lockout/tagout procedure is essential for these devices. For any journeyman electrician or master electrician working on solar, a deep knowledge of these rules is non-negotiable, ensuring every installation is safe and serviceable.

The Critical Role of Disconnecting Means in Solar Installations

As solar energy systems become more prevalent on residential and commercial properties, the role of the licensed electrician has never been more important. Ensuring these systems are safe, reliable, and compliant with the latest codes is a fundamental responsibility. For both journeyman and master electricians, a core component of this is mastering the requirements for disconnecting means as outlined in Article 690 of the NEC. These devices are not just switches; they are crucial safety mechanisms that protect homeowners, first responders, and service technicians. Properly implementing these disconnects prevents electrical shock and fire hazards, making a thorough understanding of the code essential for professional electrician training.

NEC 690.13: The Main PV System Disconnecting Means

NEC 690.13 addresses the primary disconnect required for every solar photovoltaic (PV) system. The fundamental purpose of this device is to provide a clear and accessible way to isolate the entire PV system’s conductors from all other conductors within a building or structure. This is the main point of control for de-energizing the solar array and associated circuits. It’s crucial for electricians to know how to properly identify disconnecting means to ensure full compliance.

Location: The “Readily Accessible” Mandate

One of the most important requirements of NEC 690.13 is that the disconnecting means must be installed in a “readily accessible location.” As defined in NEC Article 100, “readily accessible” means capable of being reached quickly without having to climb over or remove obstacles, or resort to using portable ladders. This ensures that in an emergency, anyone from a homeowner to a firefighter can quickly shut down the system. While the code also addresses outdoor emergency disconnects for dwellings, the PV system disconnecting means has its own specific requirements and is often located near other electrical equipment; it may be separate from the service disconnect depending on the installation.

Sizing for Safety: Interrupting Rating and Available Fault Current

A disconnect is only as good as its ability to safely open a circuit under load. NEC 690.13 requires that the PV system disconnecting means have an interrupting rating suitable for the circuit voltage and the available fault current. Electricians must perform AC/DC disconnect sizing calculations to determine the maximum current the device may need to interrupt. This involves assessing the PV system DC circuit characteristics to ensure the selected circuit breaker or switch can handle a worst-case scenario without failing. All ungrounded conductors of the PV system must be disconnected simultaneously.

Permanent Identification

Clarity is key in an emergency. The code requires that the PV system disconnecting means be permanently marked to identify it as such. This label must be clear, durable, and easily visible. A simple, properly placed label can save critical seconds and prevent confusion during a service call or emergency response.

NEC 690.15: Equipment Isolating Device for Safe Servicing

While 690.13 focuses on the entire system, NEC 690.15 deals with isolating individual pieces of equipment for maintenance, repair, or replacement. This includes devices like inverters, charge controllers, and other components. The purpose of this equipment isolating device is to allow a technician to safely work on a specific component without having to shut down the entire PV system.

2023 NEC Code Book Update: “In Sight From”

As noted above, the 2023 NEC uses the term “in sight from” for the placement of equipment isolating devices; Article 100 defines “in sight from” as visible and not more than 15 m (50 ft) distant from the other equipment. That change gives electricians more flexibility in placement while preserving the safety objective: the isolating device must be visible and readily reachable from the equipment it serves.

Lockout/Tagout Procedure and Device Type

To ensure a circuit is not accidentally re-energized during service, NEC 690.15 requires that the equipment isolating device be capable of being locked in the open position. This facilitates a proper lockout/tagout procedure, a critical safety step for any master or journeyman electrician. The device itself can be a switch, a circuit breaker, or even a connector, so long as it meets the requirements for isolation and can be locked open. When selecting hardware, it’s important to understand the difference between fused vs. non-fused disconnects and choose the appropriate one for the application.

Step-by-Step Guide to Planning PV Disconnects

Applying these NEC articles requires a systematic approach. Here is a step-by-step process for planning your disconnect strategy for a typical PV installation:

Identify All Required Disconnects: Review the system diagram. You will need one main PV system disconnecting means (690.13) and an equipment isolating device for each piece of equipment that may need service (690.15), such as the inverter.
Locate the Main System Disconnect: Choose a readily accessible location for the main 690.13 disconnect. This is often on the exterior of the building near other electrical equipment but may be located elsewhere as allowed by the NEC.
Locate Equipment Isolating Devices: For each inverter or charge controller, determine a location for its 690.15 isolating device that is “in sight from” (visible and within 15 m / 50 ft) and readily accessible from the equipment itself.
Perform Sizing Calculations: Calculate the available fault current for the PV system DC circuit. Use this value, along with the nominal system voltage, to correctly size the interrupting rating for the main system disconnect. Proper AC/DC disconnect sizing is crucial.
Select Components: Choose switches or circuit breakers that meet the calculated ratings and are listed for the purpose. Ensure they can be locked in the open position as required for equipment isolation. This is also relevant when considering a disconnect switch for other large appliances.
Plan for Labeling: Plan for clear, permanent labels for all disconnects, especially the main PV system disconnect.

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Interacting with Other Systems: Generators and Storage

Modern electrical systems often integrate multiple power sources, such as PV arrays, engine generators, and battery backup. When a PV system is installed alongside these, the disconnecting means must be planned carefully. If the system includes a transfer switch for generator backup, the PV disconnects must be installed so as to prevent backfeeding and ensure clear isolation of each power source. For DC-coupled multimode systems involving batteries, the disconnect rules in Article 690 apply to the DC circuits between the array, charge controllers, and inverter, and Article 706 covers stationary energy storage specifics.

Key Takeaways for PV Disconnecting Means

Two Types of Disconnects: NEC 690.13 covers the main system disconnect, while NEC 690.15 covers isolation for individual pieces of equipment.
Location is Key: The main disconnect must be “readily accessible.” Equipment disconnects must be “in sight from” the equipment they isolate (Article 100 defines “in sight from”).
Rating Matters: The main disconnect’s interrupting rating must be sufficient for the voltage and available fault current.
Safety First: Equipment isolating devices must be lockable to support a safe lockout/tagout procedure.
Stay Current: The 2023 NEC wording uses “in sight from”; Article 100 gives the measurable definition for that phrase.
Context with Rapid Shutdown: While disconnects de-energize circuits, they work alongside rapid shutdown requirements (NEC 690.12), which are designed to reduce rooftop shock hazards for firefighters.

Primary Sources

NFPA 70, National Electrical Code (NEC), 2023 Edition

Frequently Asked Questions (FAQ)

What is the main difference between NEC 690.13 and 690.15 for a solar PV disconnect means?

NEC 690.13 specifies the main PV system disconnecting means, which is used to isolate the entire solar system from the building’s wiring. NEC 690.15 specifies the equipment isolating device, which is used to de-energize a single piece of equipment (like an inverter) for safe service while the rest of the system might remain active.

Where should a PV system disconnecting means be located according to NEC 690.13?

The main PV system disconnect must be in a “readily accessible location,” as defined in NEC Article 100. This means it must be reachable quickly and easily without needing a ladder or moving obstacles, allowing for rapid shutdown in an emergency.

Does a lockout/tagout procedure apply to the equipment isolating device in NEC 690.15?

Yes. NEC 690.15 requires that the equipment isolating device be capable of being locked in the open (off) position. This is a critical feature to enable a safe and effective lockout/tagout procedure, protecting technicians during maintenance.

What is an interrupting rating and why is it important for a PV disconnect?

The interrupting rating is the maximum current a protective device (like a circuit breaker or switch) can safely interrupt without failing or exploding. It is a critical safety specification for the main PV disconnect (690.13) because the device must be able to handle the calculated available fault current of the PV system.

How do rapid shutdown requirements relate to disconnecting means?

Rapid shutdown requirements (NEC 690.12) and disconnecting means serve different but related safety functions. Disconnects (690.13 & 690.15) de-energize entire circuits at specific points. Rapid shutdown is designed to control conductor voltage within the PV array boundary to protect firefighters on the roof. Both are essential parts of a safe, code-compliant solar installation.