Okay, let's break this down and figure out a practical approach to getting this LED-lit shower niche project across the finish line with the inspector in Charlotte happy. I'll try to avoid jargon and focus on actionable steps.

Understanding the Inspector's Concerns

It's crucial to understand why the inspector is raising these objections. Their primary concern is safety. They're looking to ensure: Water intrusion won't create a shock hazard

This is why they're calling the stud bay behind the shower a "wet location." Even if it doesn't seem wet, the potential for moisture ingress is there.

Wiring in the plenum is fire-resistant

Plenums are areas that can circulate air for HVAC systems. If a fire occurs, standard cable insulation can release toxic fumes, which is why plenum-rated cables are required.

Addressing the Stud Bay Behind the Shower (Wet Location)

This is probably the easier of the two issues to address. Here's how I'd approach it:1. Document the Installation Properly

Take photos (and video if you can) of the entire niche assembly before you close up the wall. Show the inspector that the wiring is completely enclosed within the waterproofed niche and sealed appropriately. Document the IP67 rating of all components. Demonstrate that the light channel and wiring are truly rated for wet locations. Documentation is key.2.

Consider Extra Protection

If documentation isn't enough, consider these options for added security:

Sealing

Ensure all penetrations in the wall (where the wire enters and exits the stud bay) are sealed with a waterproof sealant (e.g., silicone caulk) that is specifically designed for electrical applications. This prevents moisture from migrating through the wall.

Conduit/Sleeve

Run the low-voltage wire through a short length of non-metallic conduit (e.g., PVC) inside the stud bay. Seal the ends of the conduit with waterproof fittings. This provides an extra layer of physical protection. The conduit does not need to run to the power supply. It is simply an encasement to protect the wire.3.

Ask the Inspector for Clarity

Respectfully ask the inspector what specific code they are citing and what, specifically, they would consider an acceptable solution for the stud bay area. This will save you time and money.

Dealing with the Drop Ceiling/Plenum

This is the trickier issue. You're right, you need plenum-rated cable in the drop ceiling. Here's how to handle it:1. Confirm the Plenum

Verify that the drop ceiling is actually a plenum. A true plenum is used to circulate air for heating or cooling. If it's just an empty space above the ceiling, it might not be considered a plenum. Check with the inspector and/or building engineer.2.

Two Key Options (Preferred Order)



Option 1: Run Entirely Plenum-Rated Cable

This is the ideal solution.

Find a Plenum-Rated, Wet-Rated Cable

This might be difficult, but it's worth researching. Look for cables that are specifically marked "CMP" (Communications Plenum) or "CL3P" (Class 3 Plenum) and that are also rated for wet locations. Note: Many plenum cables are designed for data or communications and may not be suitable for power. You'll need to find one that is rated for the appropriate voltage and current for your LED lighting. Speak to electrical supply houses.

Replace All Cable

If you can find a suitable plenum-rated, wet-rated cable, replace all the low-voltage wiring from the niche all the way to the driver. This eliminates the need for a transition point.

Option 2: Transition to Plenum-Rated Cable Outside the Plenum

This is the more common workaround.

Locate Transition Point

Choose a location outside the plenum (i.e., before the cable enters the drop ceiling) where you can safely and legally transition from the wet-rated cable to a plenum-rated cable. This transition must be done inside an approved junction box.

Approved Junction Box

The junction box must be accessible and installed according to code. Use a NEMA 3R or 4 rated enclosure (weatherproof) if there's any chance of moisture at the transition point. This is unlikely in a ceiling though.

Splice Connectors

Use appropriate, code-approved splice connectors inside the junction box to join the wet-rated cable to the plenum-rated cable. Use connectors rated for the gauge of wire.

Plenum-Rated Cable

From the junction box, run CMP- or CL3P-rated cable through the drop ceiling to the driver.

Specific Cable Considerations



Low-Voltage Cable

Because you're dealing with LEDs, you're likely using low-voltage DC wiring (e.g., 12V or 24V). Look for low-voltage cables that are specifically rated for wet locations and plenum use (if you can find one).

Gauge (Wire Size)

The gauge of the wire is critical. It must be sized to handle the current draw of the LED lights without overheating. Your electrician should be able to calculate the proper gauge based on the wattage of the lights and the length of the wire run.

Cable Markings

Always check the cable jacket for markings indicating the type of cable (e.g., CMP, CL3P), voltage rating, and wet location rating.

Examples to start your search (but always verify suitability with your electrician and local codes)



Plenum-Rated Low Voltage Lighting Cable

Search online for "CMP rated low voltage lighting cable" or "CL3P low voltage lighting cable". You may need to contact specialized electrical suppliers.

Wet-Rated Low Voltage Cable

Brands such as Cerrowire or Southwire are commonly carried at big box stores, but may not offer the combination of wet-rating and plenum rating you need. Again, speak to suppliers who work with commercial electrical projects.

Key Steps and Recommendations


Consult with a Licensed Electrician (Critical)

Even if your electrician is "stumped," get a second opinion. A qualified electrician familiar with commercial electrical codes in Charlotte is essential. They can advise on the specific cable types allowed and ensure the installation meets all code requirements. Have them provide the final solution and take responsibility.2.

Review Local Codes

Charlotte, like most jurisdictions, follows the National Electrical Code (NEC), but there may be local amendments. Your electrician should be familiar with these.3.

Talk to the Inspector

A proactive conversation with the inspector can save you a lot of headaches. Explain your proposed solution and ask for their feedback before you proceed with any changes.4.

Document Everything

Keep detailed records of all cable types, connections, and installation procedures. Photos and videos are invaluable.5.

Get Approvals in Writing

If the inspector approves a specific solution, get it in writing (email is usually fine). This will protect you if there are any future issues.6.

Avoid Shortcuts

Don't try to cut corners or use materials that are not specifically approved for the application. This can create a safety hazard and lead to costly rework.

In summary: The most straightforward (but possibly more expensive) approach is to find a single cable that is both plenum-rated and wet-rated and replace all the existing wiring. If that's not possible, focus on a safe and code-compliant transition point outside the plenum, using an accessible junction box and approved connectors. Always prioritize safety and follow the guidance of a qualified electrician. Good luck! Flag for review