PV and Rapid Shutdown Practice Questions

C. It covers solar photovoltaic systems other than large-scale photovoltaic electric supply stations, which Article 691 covers

The scope reaches interactive systems, stand-alone systems and systems that are both, with either ac or dc output for utilization. What it hands off is the large-scale supply station, which is a facility built to sell power to a regulated utility. A scope item on this article is usually testing whether you can name the article that takes what 690 declines.

NEC 2026 690.1, 691.1

A. Modules, electronic power converters, rapid shutdown equipment, hazard control equipment, Type PV wire and photovoltaic mating connectors, among others

The listing section carries a numbered list of sixteen kinds of equipment and it includes retrofit kits associated with any of them. Combiners containing overcurrent devices, charge controllers, module grounding and bonding devices and manufactured wiring harnesses are all on it. The 2026 edition puts listing requirements at the .2 position of an article, and in this article that position was vacant, so nothing behind it moved.

NEC 2026 690.2

D. Photovoltaic system circuits installed on or in buildings

The requirement is written to circuits on or in buildings, because the hazard it addresses is a firefighter cutting into a roof or leaning a ladder on a wall. Ground-mounted circuits entering a building whose sole purpose is to house photovoltaic equipment are excepted. So is equipment on nonenclosed detached structures such as carports and solar trellises.

NEC 2026 690.12

B. No, since equipment and circuits on nonenclosed detached structures of that kind are excepted

The exception names parking shade structures, carports and solar trellises and then says structures like them. The reasoning in the informational note is that the exceptions line up with the building and fire codes on where firefighters actually work on a roof. Calling the carport ground mounted is the wrong route to the right conclusion and an item can catch you with it.

NEC 2026 690.12

A. One foot from the array in all directions

The dimension is stated inside the rapid shutdown section rather than in Article 100, which is why people go looking for it in the definitions and do not find it. The same subsection then treats conductors more than three feet from their point of entry inside a building as being outside the boundary. Two different distances, both in one paragraph.

NEC 2026 690.12(B)

C. Not more than 30 volts within 30 seconds of rapid shutdown initiation

The tighter number is on the outside, because that is where people are, and the voltage is measured between any two conductors and between any conductor and ground. Nothing about rapid shutdown is instantaneous, and every limit in the section is stated as a voltage reached within a period after initiation. A choice that drops the clock is wrong however right the voltage looks.

NEC 2026 690.12(B)(1)

B. A choice between a listed photovoltaic hazard control system and holding the highest voltage to not more than 80 volts within 30 seconds

Same clock on both sides of the boundary, different voltage. Where the hazard control system is used it is installed according to the instructions in its listing, and where it needs to be told to go to its controlled state, the same rapid shutdown initiation device does the telling. This is the paragraph that has changed most across recent editions, so anything learned from a book older than 2023 is worth reading again.

NEC 2026 690.12(B)(2)

D. Nothing, since the array makes power whenever light lands on it and the function only shrinks the energized footprint around it

A module has no off, which is the fact the whole article is built around. Every other source in the book can be interrupted at its origin, and an array has the sun behind it. So the section limits how much energized conductor is left after somebody opens a disconnect, and any answer claiming the array goes dead is wrong on its face.

NEC 2026 690.12

C. Photovoltaic system direct-current circuits, and inverter output circuits originating from inverters located within the array boundary

Alternating-current output from an inverter sitting inside the array boundary is swept in, because a firefighter working near the array cannot tell one conductor from another. Inverter output from equipment outside the boundary is not controlled by this section. Circuits from arrays not attached to buildings that terminate on the exterior are excepted outright.

NEC 2026 690.12(A)

B. At an outdoor location

The general rule is that initiation devices are readily accessible, and the dwelling rule adds the outdoor location on top of it. The point is that somebody who has never been to the address can find and operate it without entering the building. The listed choices for the device itself are a service disconnecting means, a photovoltaic system disconnecting means, or a listed switch.

NEC 2026 690.12(C)(1)

A. Not more than six devices grouped together, whose combined operation shuts down all the systems on that service

The number six echoes the service disconnect rule and the reasoning is the same, that a person should not have to hunt for handles in an emergency. Grouped together is a condition, not a suggestion. For a single system, the shutdown has to occur by the operation of any one initiation device.

NEC 2026 690.12(C)(3)

D. A label at each service equipment location the systems are connected to, or another approved readily visible location, indicating where the initiation devices are

It has to include a simple diagram of a building with a roof, and the section prescribes the wording and a minimum letter height for the first line. Where a building has more than one rapid shutdown type, or has photovoltaic systems with no rapid shutdown at all, a detailed plan view of the roof is required instead. Marking is a large part of this article because the system will outlive the installer.

NEC 2026 690.12(D)

B. 1000 volts

The same sentence sets a separate and lower ceiling of 600 volts on or in one- and two-family dwellings, so the answer depends on the occupancy the stem describes. Circuits exceeding 1000 volts are sent to a wiring method subsection of their own. Maximum voltage is the highest voltage between any two conductors of a circuit or between any conductor and ground.

NEC 2026 690.7

A. Three

Correction using the module's own open-circuit voltage temperature coefficients, correction using the printed table, and a documented and stamped design by a licensed professional electrical engineer using an industry standard method. All three start from the sum of the series-connected module rated open-circuit voltages. All three correct for the lowest expected ambient temperature.

NEC 2026 690.7(A)

C. The correction factors printed in the table, which are restricted to crystalline and multicrystalline silicon modules

The restriction sits in the first four words of that method and it is the item. Find the module technology in the stem before you find the numbers, because a choice that reaches for the table anyway is wrong no matter how the arithmetic comes out. The coefficient method works for any module, since the coefficients come off that module's own listing.

NEC 2026 690.7(A)

D. 508.9 volts

Sum the series string first, so twelve times 37.2 is 446.4 volts, then apply the factor, and 446.4 times 1.14 is 508.9 volts. The 446.4 answer is the uncorrected sum, which is the number an installer would read off a datasheet on a warm afternoon. Cold is the worst case here, which is the first thing that catches people out.

NEC 2026 690.7(A), Table 690.7(A)

A. The sum of the highest short-circuit current rating of the modules connected in parallel, multiplied by 125 percent

An array is a current-limited source, so shorting a module produces only modestly more current than it makes at its operating point. A fault can sit there all day without drawing enough to open an overcurrent device, which is why the circuit is sized from a multiple of short-circuit current in the first place. The other two methods use the module listing instructions or a stamped engineering design.

NEC 2026 690.8(A)(1)

C. 30 amperes

Sum the parallel short-circuit ratings first, so two times 12 is 24 amperes, then apply the 125 percent multiplier and you have 30. The 24 ampere answer stops one step early and is the most common miss on this calculation. This figure is the maximum circuit current, and it is not yet the conductor size.

NEC 2026 690.8(A)(1)

B. 37.5 amperes

The conductor takes a second 125 percent multiplier on top of the maximum current, so 30 times 1.25 is 37.5 amperes. The conductor also has to satisfy the maximum current after adjustment and correction factors, and you take the larger of those two results. Applying only one of the two 125 percent multipliers is the error that produces the 30 ampere answer.

NEC 2026 690.8(B)(1)

D. 40 amperes, being 125 percent of the maximum current rounded up to the next standard rating

The device is rated at not less than 125 percent of the maximum current, so 37.5 amperes, and the section permits rounding up to the next standard size under the general rounding rule in Article 240. The standard ratings run 35 then 40, so 40 is the answer. An assembly listed for continuous operation at 100 percent of its rating gets to skip the multiplier.

NEC 2026 690.9(B), 240.4(B)

C. 80 volts direct current or greater between any two conductors

A direct-current arc has no zero crossing, so it burns until something physically separates far enough, which is why the article treats it as its own hazard rather than as a variation on an ac fault. The protection is a listed photovoltaic arc-fault circuit interrupter or listed components giving equivalent protection. There is an exception for circuits in metal raceways, metal-clad cable, enclosed metal cable trays or underground, under stated conditions.

NEC 2026 690.11

D. A permanent marking reading PV SYSTEM DISCONNECT or equivalent, and it has to be lockable open

The lockable open requirement can be satisfied at the disconnect, at its remote operating device, or at the enclosure providing access to it. The disconnect also has to simultaneously disconnect the photovoltaic system conductors that are not solidly grounded from all conductors of other wiring systems. Marking and lockability are two separate subsections doing two separate jobs.

NEC 2026 690.13

A. One separates the system from what it feeds, and the other isolates a piece of equipment from all of the conductors feeding it that are not solidly grounded

Equipment inside a photovoltaic system is fed from both directions at once, with an array on one side and a utility or a battery on the other, so opening one of them leaves the equipment live from the other. That is the problem the equipment disconnect solves. The system disconnect is about the building instead, and it is placed and marked so a stranger to the address can find it.

NEC 2026 690.13, 690.15

B. From the equipment grounding conductor table, using an assumed overcurrent device rated the way the article rates a real one

The general answer is the ordinary equipment grounding conductor table, and the article then supplies the missing input for a circuit that carries no device. The answer that adds a size for voltage drop inverts a sentence in the same section, which says outright that such increases are not required. Two sentences, and the item lives in the difference.

NEC 2026 690.45

D. In a bathroom

One short subsection, easily read past, and it is the kind of location item that a stem can build a whole scenario around. It sits with the general requirements at the front of the article rather than with the disconnect rules. The same subsection also permits multiple photovoltaic systems on one building and calls for a directory where they are remote from each other.

NEC 2026 690.4(D)