Solar (C-46) · Lesson 4 of 6

Rapid Shutdown Labels and DC Conductor Rules

"Rapid Shutdown Labels and DC Conductor Rules" is lesson 4 of 6 in the Solar (C-46) Learning Hub. It opens with "Why Rapid Shutdown Labels Exist" and works through 5 short steps, then a worked example you can check yourself against.

Open the free trialSee pricing

One-time purchase, no subscription. Law & Business included.

Steps in this lesson

  1. Why Rapid Shutdown Labels Exist
  2. Two Label Types, Chosen by What Shuts Down
  3. Diagram and Location: Within 3 Feet
  4. Mixed Systems and the Switch Label
  5. DC Conductor Routing and Separation

The worked example in the course applies this lesson to a realistic job in 5 steps, from "Place the label at the service disconnect" through "Label the switch".

What you'll be able to do

  • Explain the main idea of "Rapid Shutdown Labels and DC Conductor Rules" in plain language you can use on the exam.
  • Apply this step with confidence: "Diagram and Location: Within 3 Feet".
  • Apply this step with confidence: "Mixed Systems and the Switch Label".
  • Apply this step with confidence: "DC Conductor Routing and Separation".
  • Test yourself on the worked example and the quick-check quiz inside the classroom.
Rapid Shutdown Labels: CFC 1205.4ITEM 1: array + conductors shut downSOLAR PV SYSTEM EQUIPPEDWITH RAPID SHUTDOWNTURN RAPID SHUTDOWN SWITCH TO THE“OFF” POSITION TO SHUT DOWN PV SYSTEMAND REDUCE SHOCK HAZARD IN ARRAY.ITEM 2: only conductors leaving the arrayTHIS SOLAR PV SYSTEM EQUIPPEDWITH RAPID SHUTDOWNTURN RAPID SHUTDOWN SWITCH TO THE“OFF” POSITION TO SHUT DOWN CONDUCTORSOUTSIDE THE ARRAY. CONDUCTORS WITHINARRAY REMAIN ENERGIZED IN SUNLIGHT.WHERE THE LABELS GOSERVICEDISCONNECTRSD LABEL3 ft maxRAPID SHUT-DOWN SWITCHRAPID SHUTDOWNSWITCH FORSOLAR PV SYSTEM3 ft maxPlan view diagram, mixed systems:West: Item 1East: Item 2Label within 3 ft of the service disconnect; switch label within 3 ft of the switchHeader characters at least 3/8 in (10 mm); body characters at least 3/16 in (5 mm)Dotted line = areas that stay energized (Section 1205.4.2)Source: 2025 California Fire Code Sections 1205.4.1 through 1205.4.3, Figures 1205.4.1(1) and (2)CC
The diagram for this lesson, exactly as it appears in the Learning Hub.

The first steps of this lesson

Step 1: Why Rapid Shutdown Labels Exist

A PV array keeps producing voltage whenever light hits it, even when the building's power is off, so firefighters have to know which parts of the system the rapid shutdown switch actually de-energizes. 2025 California Fire Code Section 1205.4 says buildings with rapid shutdown PV systems shall have permanent labels in accordance with Sections 1205.4.1 through 1205.4.3. CFC Section 1205.1 says the electrical portion of the PV system is installed under the California Electrical Code, so the label rules here sit on top of the wiring rules.

Step 2: Two Label Types, Chosen by What Shuts Down

CFC Section 1205.4.1 Item 1 is for systems that shut down the array AND the conductors leaving the array: the first two lines are uppercase, at least 3/8 inch (10 mm) tall, black on a yellow background, and the remaining characters are uppercase, at least 3/16 inch (5 mm) tall, black on white, per Figure 1205.4.1(1). Item 2 is for systems that only shut down the conductors leaving the array: the first two lines are uppercase, at least 3/8 inch (10 mm) tall, white on a red background, and the rest are at least 3/16 inch (5 mm) tall, black on white, per Figure 1205.4.1(2). Item 2's wording ends with the warning that conductors within the array remain energized in sunlight.

The remaining 3 steps, the worked example and the quiz are in the course. This is a preview. The full lesson, with the step-by-step explanations, a worked example and a quick-check quiz, is inside the classroom.

More lessons for this trade

Browse all lesson previews

Ready to practice for real?

Try the real classroom free, no sign-up, or get the full course for your trade.

Open the free trialSee pricing

Independent exam preparation. Contractors Classroom is not affiliated with the Contractors State License Board, and no course can guarantee a passing result.