Outlet Box Extender: Fix a Shallow Electrical Box (Troubleshooting Guide)

On this page

Quick answer
Confirm the symptom
Tools and prep
Step-by-step troubleshooting
Common causes table
Parts matching
When to call a pro
FAQ
Related guides

Quick answer

Use an outlet box extender to fix shallow electrical boxes. Turn off power, measure the box, and secure the extender with screws. Reinstall the outlet and restore power.

Confirm the symptom

Outlet is recessed into the wall
Outlet faceplate is uneven with the wall
Electrical box is too shallow for new outlet

Tools and prep

Voltage tester
Screwdriver (flathead and Phillips)
Outlet box extender
Wire stripper
Needle-nose pliers
Electrical tape
Turn off power at the circuit breaker

Step-by-step troubleshooting

Turn Off Power
Do: Switch off the circuit breaker for the outlet.
Observe: Voltage tester shows no power.
Means: Power is safely off.
Next: Test the outlet with a voltage tester to confirm power is off.
Remove Outlet Cover
Do: Unscrew and remove the outlet cover plate.
Observe: Cover plate is off.
Means: Access to outlet is clear.
Next: Inspect the outlet and box.
Remove Outlet
Do: Unscrew the outlet from the box and gently pull it out.
Observe: Outlet is disconnected from wires.
Means: Outlet is ready for replacement.
Next: Check the depth of the electrical box.
Measure and Prepare
Do: Measure the depth of the electrical box and select an extender of appropriate size.
Observe: Extender matches the box dimensions.
Means: Correct extender is selected.
Next: Position the extender in the box.
Install Extender
Do: Slide the extender into the box and secure it with screws.
Observe: Extender is firmly attached to the box.
Means: Extender is properly installed.
Next: Reinstall the outlet into the extender.
Reinstall Outlet
Do: Attach the outlet to the extender and reconnect the wires.
Observe: Outlet is secure and wires are properly connected.
Means: Outlet is ready for power.
Next: Restore power and test the outlet.
Test Outlet
Do: Turn the circuit breaker back on and test the outlet with a device.
Observe: Outlet functions properly.
Means: Installation is successful.
Next: Replace the cover plate.

Common causes

Cause	Likelihood	Difficulty	Part often needed
Shallow electrical box Old or undersized boxes may not accommodate modern outlets.	Common	Easy	Outlet box extender
Improper installation Outlets installed incorrectly can appear recessed.	Sometimes	Easy–Medium	Screws, outlet
Damaged box Physical damage can cause misalignment.	Rare	Medium	New electrical box
Incorrect outlet type Using a thick outlet in a shallow box can cause issues.	Sometimes	Easy	Shallow-depth outlet
Wall construction issues Drywall thickness or uneven surfaces can affect outlet alignment.	Rare	Medium	Wall repair materials
Overloaded box Too many wires in a small box can push the outlet back.	Sometimes	Medium	Larger electrical box

Parts matching

Choose an outlet box extender that fits your electrical box size and outlet type.

Measure the depth and dimensions of your electrical box
Select an extender with the same mounting holes and size
Ensure the extender is rated for your outlet type (e.g., standard, GFCI)
Check for compatibility with your wall material (drywall, plaster, etc.)
Look for a UL-listed extender for safety compliance

Purchase a few extra screws and wire connectors in case of need.

When to call a professional

You cannot turn off power to the outlet safely
The electrical box is damaged or corroded
You are unsure about wire connections
The outlet sparks or smells burnt after installation
You hear buzzing or humming sounds from the outlet
The outlet does not work after following all steps

FAQ

Can I install an outlet box extender myself?

Yes, if you are comfortable working with electrical systems and have turned off the power. Always follow safety precautions.

Do I need a special tool to install an outlet box extender?

Basic tools like a screwdriver, voltage tester, and wire stripper are sufficient for most installations.

How do I know if my electrical box is too shallow?

If the outlet is recessed or the faceplate is uneven with the wall, the box may be too shallow. Measure the box depth to confirm.

Can I use an outlet box extender for a GFCI outlet?

Yes, as long as the extender is compatible with GFCI outlets and is UL-listed for that use.

Will an outlet box extender affect the circuit's performance?

No, an outlet box extender does not affect the circuit's performance as long as it is properly installed and rated for the outlet type.

How much does an outlet box extender cost?

Outlet box extenders typically cost between $5 and $20, depending on the size and brand.