Reverse polarity occurs when the hot and neutral wires are connected to the wrong terminals on an outlet. This can create a shock hazard and damage electronics. Fixing it involves turning off power and reconnecting the wires correctly—black to brass, white to silver, and ground to green.
An electrical outlet may look perfectly normal and still be wired incorrectly. This condition, called reverse polarity, happens when the hot and neutral wires are swapped. Although many devices may still work, the outlet is unsafe and should be corrected.
The good news is that reverse polarity is usually easy to diagnose and fix with a simple outlet tester and a careful inspection of the wiring connections.
Quick Answer
Test the outlet with a plug-in circuit tester. If it indicates reverse polarity, turn off power at the breaker, remove the outlet, and reconnect the wires so the black (hot) wire goes to the brass terminal and the white (neutral) wire goes to the silver terminal.
What Is Reverse Polarity?
A standard electrical outlet has three connections:
- Hot (black) wire → brass terminal
- Neutral (white) wire → silver terminal
- Ground (bare or green) wire → green screw
Reverse polarity occurs when the hot and neutral wires are connected to the wrong terminals. This means electricity is flowing through the outlet incorrectly, which can create safety risks.
Why It’s Dangerous
Even though devices may still operate, reverse polarity can:
- Increase the risk of electrical shock
- Leave parts of appliances energized when they should be off
- Damage sensitive electronics
- Interfere with proper circuit protection
Because the outlet appears normal, this condition often goes unnoticed unless it is tested.
Symptoms & What They Mean
| Symptom | Likely Cause |
|---|---|
| Outlet tester shows “reverse polarity” | Hot and neutral wires are swapped |
| Devices work but seem unsafe or inconsistent | Incorrect wiring affecting current flow |
| Shock when touching plugged-in device | Improper grounding or reversed wiring |
| No visible problem | Reverse polarity often has no obvious signs |
How to Test for Reverse Polarity
The easiest way to detect reverse polarity is with a plug-in circuit tester.
- Plug the tester into the outlet
- Observe the light pattern
- Compare it to the tester’s guide
These testers can identify:
- Reverse polarity
- Open ground
- Live circuits
If the tester indicates reverse polarity, the outlet needs to be corrected.
How to Fix Reverse Polarity
1. Turn Off the Power
Shut off the circuit breaker that serves the outlet. Use a voltage tester to confirm the outlet is not live.
2. Remove the Outlet
Unscrew the cover plate and remove the mounting screws. Carefully pull the outlet out of the electrical box.
3. Inspect the Wiring
Check where the wires are connected:
- Black wire should be on the brass terminal
- White wire should be on the silver terminal
4. Correct the Connections
If the wires are reversed, disconnect them and reconnect:
- Black (hot) → brass screw
- White (neutral) → silver screw
- Ground → green screw
5. Reinstall the Outlet
Push the wires back into the box, secure the outlet, and reinstall the cover plate.
6. Restore Power and Test
Turn the breaker back on and test the outlet again with a circuit tester to confirm the issue is resolved.
If you need help with proper wiring technique, see How to Wire an Electrical Receptacle.
What If the Problem Persists?
If the tester still indicates reverse polarity after correcting the wiring:
- The problem may be upstream in another outlet or junction
- There may be a wiring issue elsewhere in the circuit
In this case, the safest option is to have the circuit inspected by a professional.
When to Call an Electrician
- You are unsure which wire is hot or neutral
- Multiple outlets show reverse polarity
- The wiring does not match standard color coding
- The problem persists after rewiring
Find an Electrical Pro Near You
Related Problems
FAQ
What causes reverse polarity?
It occurs when the hot and neutral wires are connected to the wrong terminals on an electrical outlet.
Is reverse polarity dangerous?
Yes. It increases the risk of shock and can damage electrical devices.
How do I know if my outlet has reverse polarity?
Use a plug-in circuit tester, which will indicate if the wiring is incorrect.
Can I fix reverse polarity myself?
Yes, if you are comfortable working with wiring and follow proper safety procedures.
Will an outlet still work with reverse polarity?
Yes, but it will not be safe and should be corrected.
Can reverse polarity damage electronics?
Yes. Sensitive electronics can be affected by improper wiring.
