How to Replace a Lighted Medicine Cabinets | Safe DIY Guide

lighted medicine cabinets

Written by Mike Reynolds – Former licensed electrician and lead installation consultant for Havenseek Lighted Medicine Cabinets, served 800+ clients across North America, with over 12 years of hands-on experience completing 1,200+ bathroom fixture installations. This guide is distilled from real-world field work, not just theory.

Staring at your dated, dim bathroom and dreaming of the clear, bright illumination from a modern lighted medicine cabinet? That dream is often crushed by a wave of anxiety. “What if I get shocked?” “What if I hit a pipe?” “What if it falls off the wall?” I’ve heard these fears a thousand times. That’s exactly why this guide exists. Forget vague tutorials; this is a field-tested, safety-obsessed blueprint that will walk you, step-by-step, through how to replace a medicine cabinet with a new, gorgeous lighted version. By the end, you won’t just have a new fixture—you’ll have the confidence that comes from doing it right. This is the only guide you need to read.

Table of Contents

lighted medicine cabinets

Section 1: Safety First – The Critical Pre-Installation Audit

Rushing into this project is the single biggest mistake. This stage is about gathering intelligence on your bathroom’s “infrastructure.” Skipping it is like building a house without checking the land. The goal for your new medicine cabinet with lights is a perfect, safe, and lasting fit.

Your Professional-Grade Tool & Material Checklist

Nothing kills momentum faster than stopping mid-job to run to the hardware store. Use this checklist as your shopping list. I’ve separated “Absolute Must-Haves” from “Pro-Recommended” tools that make life easier.

Tool/MaterialCategoryWhy You Need It
Non-Contact Voltage TesterMUST-HAVEYour primary life-saver. Confirms wires are dead BEFORE you touch them.
#2 Phillips ScrewdriverMUST-HAVEFor removing old screws and installing new ones.
4-ft LevelMUST-HAVEEnsures your cabinet is perfectly horizontal. Crooked is unacceptable.
Drill/Driver & Drill BitsMUST-HAVEFor pilot holes and driving screws into studs or anchors.
Wire Strippers & CuttersMUST-HAVEFor preparing electrical wires for safe connections.
Wire Connectors (Wire Nuts)MUST-HAVETo securely join electrical wires. Get the correct size for your wire gauge.
Electrical TapeMUST-HAVETo wrap wire nuts for an extra layer of safety and security.
Stud FinderRECOMMENDEDLocates wooden wall studs for the strongest possible mount.
Drywall Saw / Jab SawRECOMMENDEDIf you need to slightly enlarge the wall opening.
Painter’s Tape & PencilRECOMMENDEDFor marking drill points and layout lines without damaging walls.

Understanding Your Wall and Electrical Reality

This is where DIYers get surprised. You need to know what’s behind that drywall.

Wall Type Identification:

  • Drywall: Most common. You’ll need to find studs or use heavy-duty toggle bolts.
  • Plaster over Lathe: Older homes. More brittle, requires careful drilling and special anchors.
  • Tiled Wall: Requires a carbide-tipped drill bit to prevent cracking. Mounting is trickier.

The Non-Negotiable Electrical Safety Protocol:

  1. Go to your main circuit breaker panel and flip the switch that controls the bathroom vanity light or old cabinet to OFF.
  2. Return to the bathroom. Turn the old light switch ON and OFF. The light should NOT work. This is your first check.
  3. Now, use your non-contact voltage tester. Place it near the wires inside the old cabinet (you may need to remove a cover plate). The tester must NOT beep or light up. This is your critical second verification. Never trust just the breaker label or light switch.

Choosing the Right New Lighted Medicine Cabinet

Your new lighted medicine cabinet must be a match for your space and skills.

  • Size is King: Measure the width, height, and depth of your existing wall opening and the overall dimensions of the old cabinet. Your new one should be at least as wide as the opening.
  • Wet Location Rating: For bathrooms, especially near showers, ensure the cabinet is rated for “damp” or “wet” locations. This means sealed electronics.
  • Power Source: Most are “hardwired.” Some have a plug. Know which one you have, as it affects your electrical plan.

Section 2: Demolition – Removing the Old Cabinet Cleanly

With power confirmed OFF, you can begin disassembly. Work slowly to avoid damaging the wall, which will make your new installation harder.

Step-by-Step Removal Process

  1. Remove the Cabinet Door(s): Open the door and look for hinge pins or screws. Carefully detach the door and set it aside.
  2. Clear the Interior: Take out all shelves and any interior mounting brackets that are part of the cabinet itself.
  3. Locate the Main Mounting Points: Look inside the cabinet box. You will find screws in the top corners, bottom corners, or along the sides. These secure the cabinet box to the wall or a mounting bracket.
  4. Unscrew and Support: Use your screwdriver or drill to remove these screws. Have a helper support the cabinet’s weight as you remove the last screws to prevent it from crashing down.
  5. Disconnect the Wires (If Present): Gently pull the cabinet away from the wall. If it was wired, you’ll see wires connected with wire nuts. Unscrew the wire nuts, separate the cabinet’s wires from the house wires, and tuck the house wires safely back into the electrical box.
medicine cabinet with lights

Prepping the Workspace for the New Star

Now, assess the opening. Remove any old caulk or adhesive. If the drywall edges are crumbled, you may need to patch small sections. The goal is a clean, stable surface for your new medicine cabinet with lights to mount against. This is also the time to check if the existing electrical box is in good condition and properly secured.

Section 3: Installation – Precision Mounting for a Rock-Solid Hold

This phase determines whether your cabinet feels flimsy or feels like part of the house. We are building a foundation that will hold significant weight for decades.

Installing the New Mounting Bracket or Cleat

Most high-quality lighted medicine cabinets use a metal mounting bracket. This is the single most important piece.

  1. Find and Mark Studs: Use your stud finder to locate the studs on either side of the opening. Mark their edges with pencil and painter’s tape.
  2. Position the Bracket: Hold the bracket in place, centered in the opening. It must be perfectly level. Use your 4-ft level across the top of the bracket.
  3. Mark and Drill Pilot Holes: Mark the screw holes on the bracket that align with the wall studs. Drill small pilot holes into the studs at these marks.
  4. Secure the Bracket: Using long, thick wood screws (usually 2.5 to 3 inches), drive them through the bracket and into the wall studs. Tighten until the bracket is immovable. If you cannot hit two studs, you must use heavy-duty hollow-wall anchors rated for the cabinet’s weight.

Hanging and Securing the Cabinet Body

This is the rewarding “big reveal” moment. With the bracket secured, carefully lift the new lighted medicine cabinets and hook it onto the bracket. You should hear or feel a solid engagement. Have your helper steady it. Inside the cabinet, there will be additional screws (often at the top) that you must drive into the bracket to permanently lock the cabinet in place. Do not skip these!

Section 4: Electrical Connection – The Safe Heart of Your Lighted Cabinet

Pay attention. This is the most critical part of the entire guide. A poor wire connection causes flickering lights, failed components, or a fire hazard.

Understanding Basic Bathroom Wiring

In a standard US setup, you’ll see three wires coming from the wall:

  • Black (or Red): The “Hot” wire – carries the live current.
  • White: The “Neutral” wire – completes the circuit.
  • Bare Copper or Green: The “Ground” wire – a critical safety path to prevent shock.

Your new medicine cabinet with lights will have corresponding wires, often labeled or color-coded the same way.

The Step-by-Step, Safe Wiring Procedure

  1. Prepare the Wires: Strip about 3/4 inch of insulation from the ends of the house wires and the cabinet wires, if not already done.
  2. Make the Connections:
    • Twist the black wire from the house together with the black wire from the cabinet.
    • Twist the white wire from the house together with the white wire from the cabinet.
    • Twist the ground wires together (copper to copper/green).
  3. Secure with Wire Nuts: Place a correctly sized wire nut over each pair of twisted wires. Screw it on clockwise until it is very tight. Give a gentle tug on each wire to ensure it’s held fast.
  4. Insulate with Electrical Tape: Wrap electrical tape around the base of the wire nut and down onto the wire insulation. This prevents the nut from accidentally loosening over time.
  5. Neatly Tuck Wires: Carefully fold the connected wires back into the electrical box in the wall. Ensure no bare wire is exposed.

The Moment of Truth: Pre-Closure Testing

DO NOT put the back cover on yet! Go back to the circuit breaker and turn the power back ON. Return to the bathroom and flip the light switch or touch the sensor (if your cabinet has a touch switch). The lights should turn on perfectly. If they don’t, turn the power OFF again and re-check every connection. Once confirmed working, turn the power OFF one final time to secure the back cover.

Section 5: Finishing Touches – Sealing, Testing, and Enjoying

You’re on the home stretch. These final steps ensure longevity and a professional look.

Sealing Against Moisture for Longevity

Bathroom steam is the enemy of drywall and cabinetry. Apply a thin, continuous bead of high-quality mold-resistant silicone caulk along the top and sides where the cabinet meets the wall. Smooth it with a damp finger for a clean, waterproof seal. This prevents moisture from creeping behind the cabinet.

Final Assembly and Operational Guide

Install any mirrors, doors, and interior shelves according to your cabinet’s manual. Now, turn the power ON for the final time. Test all features: the main lights, side lights, defogger (if equipped), and outlet (if equipped). Take a moment to appreciate the dramatic transformation.

Simple Maintenance for Your Investment

To keep your lighted medicine cabinets looking and working like new:

  • Cleaning: Use a soft, damp cloth and mild glass cleaner. Avoid abrasive sprays directly on the frame or switches.
  • Bulb/LED Replacement: If using replaceable bulbs, ensure power is OFF before changing. Most integrated LED modules are not user-serviceable and have long lifespans.

Feel Overwhelmed or Have a Complex Project?

You’ve just absorbed a masterclass in safe installation. For large-scale projects, custom-sized lighted medicine cabinets, or if you’d simply prefer a guaranteed professional result, the Havenseek Mirror team is here. Our experts handle everything from specification to final installation.

Get a Free, No-Obligation Project Consultation & Quote Within 12 Hours.Request Your Free Professional Quote Now

how to replace a medicine cabinet

Frequently Asked Questions (FAQ)

Do I need a permit to replace a medicine cabinet with a lighted one?

Typically, a simple like-for-like replacement where you’re using existing wiring does not require a permit. However, if you are running new electrical circuits, altering the wall structure significantly, or if your local building codes are strict (especially for wet locations like bathrooms), a permit may be needed. Always check with your local municipal building department to be absolutely sure. When in doubt, getting a permit ensures your installation is inspected for safety.

What if there’s no existing electrical wire behind my old cabinet?

If there’s no power, you have three main options: 1) Hire a licensed electrician to run a new circuit or extend an existing one from a nearby outlet or light switch. This is the safest and most permanent solution. 2) Choose a battery-operated lighted medicine cabinets, though these are less bright and require battery changes. 3) Use a plug-in model and run a discreet cord to the nearest GFCI outlet, which can be a tripping hazard and is often not the cleanest look. For a professional and safe result, Option 1 is highly recommended.

My new LED lights on the medicine cabinet flicker or don’t turn on. What did I do wrong?

Flickering or failure to turn on usually points to an electrical connection issue. First, double-check that the circuit breaker is ON. Then, turn the power OFF again and reopen the cabinet. Inspect your wire connections (wire nuts). Ensure the black (hot) wires are tightly connected together, the white (neutral) wires are connected, and the ground wires (copper/green) are secured. Loose connections are the #1 cause. Also, verify that the wall switch (if used) is functioning. If the connections look good, the issue could be with the cabinet’s LED driver—contact the manufacturer (like Havenseek Mirror) for support.

The new lighted cabinet is slightly smaller than the old hole in the wall. How do I fix the gap?

A small gap is common and fixable. You have two professional options: 1) Install a ‘beauty ring’ or ‘escutcheon’ panel that comes with many cabinets or can be purchased separately. This flat panel covers the gap. 2) For a seamless look, patch the drywall around the new cabinet. Use drywall joint tape and compound to fill the gap, sand smooth, and repaint the entire wall section. This method is more labor-intensive but gives the most integrated, custom appearance.

Can I install a lighted medicine cabinets on a tiled wall?

Yes, but it requires special tools and care. You will need a carbide-tipped glass and tile drill bit to drill through the tile for your mounting screws. Drill slowly to prevent cracking the tile. Use a hollow wall anchor designed for tile or, ideally, locate the wall studs behind the tile for the most secure mount. The added thickness of the tile and adhesive may also require longer mounting screws, which are often not included with the cabinet. Always measure and plan before drilling.

References & Further Reading

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