User: 1.21 Gigawatts, Location: Norwalk, CT
Asked on: Tuesday, June 10, 2025 at 2:34 pm EDT
Answered on: Tuesday, June 10, 2025 at 2:36 pm EDT
Question: I want to use a plug in cord for the disposal and have a GFI under the sink for it but I need the switch to be in the backsplash near the sink. Can that switch on the countertop switch the GFI under the sink in the cabinet?Wired like this? Don't worry, grounds will be all done and I plan on having a neutral in the switch box doing nothing. Running 12-3 to switch box.OR.. should I get one of those GFI switches for the countertop since there are no receptacles near the sink. Would still need GFI under the sink for the cord to plug into so not sure how that all would be wired.
Okay, let's break down the disposal wiring with a switch and GFI, keeping safety paramount and aligning with best practices. There are a couple of ways to accomplish this, but it's critical to understand the principles involved.
Understanding the Goal
You want a switch near the sink (in the backsplash) to control the disposal, but also want GFI protection for it because it's near water.
Here's a breakdown of the options and how they're wired, including important safety considerations
Option 1: Standard Switch Controlling a GFI Receptacle (Under Sink) Concept
A standard switch on the counter controls power to a GFI outlet under the sink. The disposal then plugs into that GFI outlet.
Wiring
Power Source
A dedicated 12/3 w/ground (black/red/white/ground) wire runs from your breaker panel to the switch box in the backsplash.
IMPORTANT
This circuit MUST be dedicated to the disposal. Do not tap into an existing under-sink circuit.2.
Switch Box
Connect the black wire from the panel to one terminal on the switch. Connect a new black wire from the other terminal on the switch and run it through the 12/3 cable back down to the under-sink area. This is your "switched hot." This will be your red wire. (Tape both ends red to signal it's being used as a hot) Connect the white (neutral) wire from the panel to the white (neutral) wire going down to the receptacle. These are joined together permanently. Connect the ground wire from the panel to the ground wire going down to the receptacle, and to the metal box (if applicable) if the box is metal.3.
Under-Sink Receptacle Box (GFI)
Connect the red "switched hot" wire from the switch to the Line (Hot) terminal on the GFI receptacle. Connect the white (neutral) wire from the switch to the Line (Neutral) terminal on the GFI receptacle. Connect the ground wire from the switch to the ground terminal on the GFI receptacle.
Important: Leave the LOAD terminals of the GFI receptacle empty. The disposal plugs into this GFI outlet. Pros
Simple to understand and wire. Uses readily available components. Proper GFI protection.
Cons
Requires running 12/3 cable.
Option 2: GFI Circuit Breaker at the Panel (Recommended) Concept
This is the safest and best practice approach. Instead of a GFI receptacle under the sink, you use a GFI circuit breaker at your main electrical panel to protect the entire disposal circuit.
Wiring
Power Source
A dedicated 12/2 w/ground (black/white/ground) wire runs from your GFI breaker at the panel to the switch box in the backsplash.
IMPORTANT
This circuit MUST be dedicated to the disposal. Do not tap into an existing under-sink circuit.2.
Switch Box
Connect the black wire from the panel to one terminal on the switch. Connect a new black wire from the other terminal on the switch and run it through the 12/2 cable back down to the under-sink area. This is your "switched hot." Connect the white (neutral) wire from the panel to the white (neutral) wire going down to the receptacle. These are joined together permanently. Connect the ground wire from the panel to the ground wire going down to the receptacle, and to the metal box (if applicable) if the box is metal.3.
Under-Sink Receptacle Box (Standard Receptacle)
Connect the black "switched hot" wire from the switch to the Hot terminal on the standard receptacle. Connect the white (neutral) wire from the switch to the Neutral terminal on the standard receptacle. Connect the ground wire from the switch to the ground terminal on the standard receptacle. The disposal plugs into this standard outlet.
Pros
Safest option: GFI protection for the entire circuit. Easier to test GFI protection (at the breaker). Less chance of nuisance trips.
Cons
Requires a GFI circuit breaker (more expensive than a GFI receptacle).
Option 3: GFI Switch in Backsplash (Not Recommended unless... see notes) Concept
A GFI switch replaces a standard switch in the backsplash.
Wiring
This is extremely complex and depends heavily on the exact model of GFI switch. You would still need a receptacle under the sink, and this complicates the wiring considerably. Furthermore, GFI switches are not typically designed for this application and might not be code-compliant.
Pros
Potentially cleaner look (all-in-one device).
Cons
Highly Complex Wiring. Potentially Not Code Compliant. Harder to troubleshoot. Increased Risk of Miswiring. May not be rated for disposal load.Important Considerations and Warnings Dedicated Circuit
Always use a dedicated circuit for the disposal. Do NOT tap into existing circuits. This is critical for safety and to prevent overloading the circuit.
Wire Gauge
12 gauge wire is sufficient for a 20-amp circuit, which is standard for disposals.
Local Codes
Always comply with your local electrical codes. They may have specific requirements for disposal wiring and GFI protection. When in doubt, consult a licensed electrician.
Grounding
Absolutely essential. All grounds must be properly connected.
Professional Help
If you are not completely comfortable with electrical wiring, hire a qualified electrician. Electrical work can be dangerous, and improper wiring can lead to fire or electrocution.
Testing
After wiring, use a multimeter to verify that the wiring is correct before energizing the circuit. Test the GFI protection by pressing the "Test" button on the GFI device (receptacle or breaker).
Neutral in Switch Box
Yes, include a neutral wire in the switch box, even if it's not immediately used. Future devices may require it.
Tamper-Resistant Receptacle
Use a tamper-resistant (TR) receptacle if the disposal outlet is readily accessible to children.
RecommendationThe best option is to use a
GFI circuit breaker (Option 2) at the panel and a standard receptacle under the sink. It offers the best protection and is easier to troubleshoot.If you must use a GFI receptacle,
Option 1 is the next best.
Under no circumstances should you attempt Option 3 without expert guidance and verification that the GFI switch is specifically designed for this type of application and is compliant with local codes.Before starting any electrical work, turn off the power at the breaker panel to the circuit you will be working on. Double-check with a non-contact voltage tester to ensure the power is off. Safety first! Flag for review