What Happens If Hot and Neutral Wires Are Reversed?

What Happens If Hot and Neutral Wires Are Reversed?

Reversed polarity — connecting the hot wire to the neutral terminal and the neutral wire to the hot terminal — is one of the most common wiring mistakes in residential electrical work. It is also one of the most dangerous, because the circuit may appear to function normally while creating a serious shock hazard.

Why Reversed Polarity Is Dangerous

• In a correctly wired outlet, the switch contact on a lamp or appliance breaks the hot side of the circuit. With reversed polarity, the switch breaks the neutral side — the lamp’s socket shell and the metal case of many appliances remain energized even when the switch is off
• Replacing a light bulb in a reversed-polarity socket risks contact with an energized socket shell, even with the switch in the off position
• Appliances with two-prong plugs (not polarized) can be plugged in either orientation and may energize their chassis
• Reversed polarity at an outlet also affects any GFCI downstream on that circuit — the GFCI may not function correctly if polarity is reversed at the device upstream

How to Check for Reversed Polarity

A simple plug-in outlet tester — available at hardware stores for under $10 — identifies reversed polarity instantly. The tester plugs into the outlet and uses indicator lights to show whether polarity is correct, reversed, open, or has other wiring faults. A licensed electrician will use a multimeter to confirm and trace the source of the reversal to the panel.

EZSMART identifies and corrects reversed polarity and other outlet wiring faults across Ontario. If your outlet tester shows a wiring fault, contact us to trace and repair it.

Amir Azimipour

Electrician Since 2008 Journeyman Electrician Designated Master Electrician at EZSMART Corp