Bathroom Electrical Rough-In
Power and light come to your new bathroom. Running wiring for outlets, lighting, exhaust fans, and heated floors must be done right—electrical work in bathrooms has strict code requirements for safety around water.
Quick Summary
Time required
1-2 days
Typical cost
$800-2,000
Difficulty
Pro required
Critical Bathroom Electrical Code Requirements
Bathrooms are wet environments where electricity poses serious danger. The electrical code has specific requirements that must be followed—no exceptions.
GFCI Protection Mandatory
All bathroom outlets must have GFCI (Ground Fault Circuit Interrupter) protection. GFCI detects current leaks and shuts off power in 1/40th of a second, preventing electrocution. Install GFCI outlets or use GFCI breaker for entire circuit.
Dedicated 20-Amp Circuit for Outlets
Bathroom outlets require at least one 20-amp circuit that doesn't serve other rooms. This circuit can serve multiple bathrooms but not other areas. Use 12-gauge wire (12/2 Romex) for 20-amp circuits.
Exhaust Fan Required (If No Window)
Bathrooms without operable windows must have mechanical exhaust vented to outside. Minimum 50 CFM for rooms under 100 sq ft, or 1 CFM per square foot for larger bathrooms. Fan must be on separate switch from lights or have timer/humidity sensor.
Lighting Circuit Can Be Shared
Bathroom lights can share a 15-amp circuit with lights in other bathrooms or hallways. Lights don't need GFCI protection unless the fixture is within shower/tub zone. Use 14-gauge wire (14/2 Romex) for 15-amp lighting circuits.
Special Circuits for High-Draw Items
Heated floors, jetted tubs, and towel warmers typically require dedicated circuits. Heated floors often need 15-20 amps depending on size. Always follow manufacturer's specifications for circuit requirements.
Step-by-Step Rough-In Process
Plan Your Electrical Layout
Map out all electrical needs before running wire. Consider current needs plus future additions like electric towel warmers or upgraded lighting.
Typical bathroom electrical needs:
- •Vanity lights: centered above mirror, 36\"-40\" apart for double sinks
- •GFCI outlets: near sink, inside vanity cabinet, far wall
- •Exhaust fan: centered in room or over shower/tub
- •Shower/tub lights: recessed or moisture-rated fixtures
- •Heated floor mat: thermostat on wall outside shower area
- •Night light: low-level LED in baseboard or toe-kick
Install All Electrical Boxes
Mount boxes for outlets, switches, and ceiling fixtures before running wire. Box placement must be precise for tile and fixture alignment.
Run Cables From Breaker Panel
Route Romex from electrical panel to bathroom. Plan the path to minimize holes through studs and avoid other utilities.
Wire sizing:
- 14/2 Romex: 15-amp circuits (lighting, small loads)
- 12/2 Romex: 20-amp circuits (outlets, required)
- 10/2 Romex: 30-amp circuits (electric water heaters)
- Number after slash is wire count (2 = hot + neutral, 3 = hot + hot + neutral)
- All Romex includes bare ground wire
Installation rules: Staple cable within 12\" of boxes and every 4.5 feet along runs. Drill holes in center of studs, minimum 1.25\" from edge. Protect cables with metal plates if within 1.25\" of stud face. No sharp bends—minimum 5× cable diameter bend radius.
Wire Exhaust Fan and Switches
Exhaust fans have specific wiring requirements. Many now include lights, heaters, or humidity sensors requiring multiple switches or special controls.
Common fan wiring configurations:
- Basic fan: 14/2 from switch to fan. Switch interrupts hot wire.
- Fan + Light: 14/3 from switch to fan. Allows separate control of fan and light.
- Humidity sensor: Constant power to fan, automatic operation when humidity rises.
- Timer switch: Runs fan for set time after switch off. Recommended for moisture control.
Install GFCI Outlet Wiring
All bathroom outlets must be GFCI-protected. You can wire multiple outlets to one GFCI outlet (protecting downstream) or install GFCI at each location.
Option 1: GFCI Breaker
Install GFCI breaker in panel. All outlets on circuit are protected.
✓ Protects entire circuit
✓ Regular outlets at fixtures
✗ More expensive
Option 2: GFCI Outlets
Install GFCI at first outlet, regular outlets downstream.
✓ Less expensive
✓ Easy to test and reset
✗ Must wire correctly
Run Heated Floor Wiring (If Applicable)
Electric radiant floor heating requires dedicated circuit and GFCI protection. Install mat according to manufacturer specs before tiling.
Important: Test heated floor mat resistance before, during, and after tile installation. One nick in the wire ruins the entire mat. Document resistance readings. Run conduit from mat to thermostat for sensor wire protection. GFCI protection is mandatory for heated floors.
Label All Circuits and Schedule Inspection
Label every cable at the panel and at boxes. Schedule rough-in inspection before closing walls. Inspector must approve before proceeding.
Electrical inspector checks:
- Correct wire sizing for circuit amperage
- Proper stapling and protection of cables
- GFCI protection on all required circuits
- Box fill calculations (not overstuffed)
- Adequate boxes for device count
- Proper grounding and bonding
- Minimum clearances from water sources
- Correct circuit labeling in panel
Electrical Safety in Bathrooms
Water and electricity are deadly together
Even a small amount of water on your hands reduces skin resistance, making electric shock far more dangerous. This is why GFCI protection is mandatory—it can save your life. Never bypass or remove GFCI protection.
Always turn off power at panel
Before working on any electrical, shut off power at the breaker panel. Test with voltage tester to confirm power is off. Lock out the breaker if others might turn it on. One mistake can be fatal.
Hire a licensed electrician if uncertain
Electrical mistakes cause house fires, electrocutions, and failed inspections that require expensive corrections. Unless you have electrical training and understand code, hire a professional. It's not worth the risk.
Frequently Asked Questions
Are GFCI outlets required in bathrooms?
Yes, all bathroom outlets must be GFCI (Ground Fault Circuit Interrupter) protected by code. GFCI outlets detect ground faults and shut off power in milliseconds, preventing electrocution in wet environments. Install GFCI outlets within 3 feet of sink edges and anywhere else in the bathroom.
Does a bathroom need a dedicated electrical circuit?
Code requires at least one 20-amp circuit for bathroom outlets, and this circuit cannot serve other rooms. Lighting and exhaust fans can share a circuit with other bathrooms or hallways, but outlets must be dedicated. If you have high-draw items like heated floors or a jetted tub, those require separate dedicated circuits.
Is an exhaust fan required in a bathroom?
Code requires either an operable window or a mechanical exhaust fan in bathrooms. If there's no window, an exhaust fan is mandatory. The fan must be vented to the outside (not into attic or wall cavity) and sized for the room: minimum 50 CFM for bathrooms under 100 sq ft, 1 CFM per square foot for larger bathrooms.
Can I do my own bathroom electrical rough-in?
You can do electrical work in your own home in most jurisdictions, but you must pull permits and pass inspections. However, electrical work is dangerous and code-intensive. One mistake can cause fires, electrocution, or failed inspections that require tearing out work. Unless you have electrical experience, hire a licensed electrician. Typical cost for bathroom rough-in is $800-2,000.
How high should bathroom outlets be installed?
Standard outlet height is 15-18 inches above finished floor, though code doesn't specify exact height. Outlets near sinks should be 12-18 inches to side of sink and minimum 6 inches above backsplash or countertop. GFCI outlets must be readily accessible (not behind furniture). Switch height is typically 48 inches to center.
Electrical Rough-In Complete
With electrical approved, you can proceed with framing any new walls. All rough work must be inspected before closing up walls with drywall and backer board.