LG Dryer nP: Half Your Power Supply Is Missing

nP means the dryer detected voltage on only one leg of its 240V supply circuit. An electric dryer requires two 120V legs (L1 and L2) that together provide 240V for the heating element. The motor, controls, and drum light run on 120V (one leg to neutral). The heater needs 240V (L1 to L2). If one leg is dead, the motor runs and the drum tumbles but the heater cannot energize — your dryer tumbles cold.

Why This Is Not a Dryer Problem

nP is almost never caused by a dryer component failure. It is a power supply problem — something between your breaker panel and the dryer outlet has lost one of the two hot legs.

The Dryer Circuit Explained

A standard electric dryer in the US uses a dedicated 30A, 240V circuit. At the breaker panel, this is a double-pole breaker — two breakers tied together that should trip simultaneously. Each breaker provides one 120V leg. If one half of this double-pole breaker trips independently (a rare but documented failure mode), the dryer receives 120V on one leg and 0V on the other.

Result: the drum spins (motor runs on the live leg), the controls work, but the heater gets 0V instead of 240V. The board detects the missing voltage and displays nP.

Diagnosing nP

Step 1: Check the Breaker Panel

Go to your breaker panel. Find the dryer's double-pole breaker. Flip it fully off, then fully on. If one side was tripped without the other, this resets both. Test the dryer — if nP clears, one side of the breaker had tripped.

If the breaker trips again within minutes or days, you have either a wiring issue (partial short on one leg) or a failing breaker that needs replacement by an electrician.

Step 2: Check the Outlet Voltage

Using a multimeter at the dryer outlet:

• L1 to L2: should read 240V (+/- 5%). If you read 120V, one leg is dead
• L1 to Neutral: should read 120V
• L2 to Neutral: should read 120V. If this reads 0V, L2 is the dead leg

If you read 120V on L1-to-Neutral and 0V on L2-to-Neutral, the problem is confirmed at one leg of the supply.

Step 3: Trace the Dead Leg

If the breaker reads correctly (240V at the breaker output terminals) but the outlet reads 120V, the break is in the wire run between the panel and the outlet. Possible causes:

• A wire nut connection in a junction box along the run has come loose
• A rodent chewed through one wire
• An older aluminum wire connection has corroded (high-resistance aluminum-to-copper connection)
• The outlet itself has a burned or broken contact on one leg

The Most Common nP Scenario

The dryer was working fine. A thunderstorm hit. Afterward, the dryer tumbles but does not heat. nP appears on the display.

What happened: a lightning surge or power grid fluctuation tripped one side of the double-pole breaker. The two sides of a double-pole breaker are supposed to trip together, but mechanical wear or manufacturing variance can allow one side to trip independently.

Fix: flip the breaker fully off, wait 5 seconds, flip fully on. nP clears. If this happens repeatedly, the breaker's trip mechanism is worn and should be replaced ($15-30 for the breaker plus electrician labor).

nP on Gas Dryers: Different Story

nP should not appear on gas LG dryers because gas dryers use a standard 120V, 15A circuit. If you see nP on a gas dryer, the board may have a firmware mismatch (wrong board installed) or the gas valve circuit is not receiving power from the board's internal relay. This is unusual and requires board-level diagnosis.

Parts and Cost

nP vs. PS: Both Are Power Problems

nP specifically identifies that one leg of 240V is missing — the dryer sees 120V total. PS (power supply error) is a broader code that includes complete power loss events, voltage sag below threshold, or internal power supply failure. nP is always an external circuit issue. PS can be either external or internal.

Living With nP Temporarily

The dryer runs on timed cycles at 120V but with no heat. You can tumble-dry on air-only (fluff) setting while waiting for an electrician. Clothes will not dry from heat but the tumbling action does help with wrinkles and air-circulation drying for lightly damp items.

Do not attempt to jumper, bypass, or modify the dryer's wiring to compensate for a missing leg. The external circuit must be repaired at the source — breaker, wiring, or outlet.

When to Call an Electrician vs. Appliance Tech

nP is an electrical circuit problem, not an appliance repair. Call an electrician if:

• The breaker is tripping repeatedly on one side
• The outlet shows less than 240V between L1 and L2
• You smell burning at the outlet or breaker panel
• The outlet shows scorch marks or feels warm

Call an appliance tech only if the outlet reads correct 240V and nP persists — this would indicate a dryer power cord failure or board input issue, both uncommon.

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LG dryer tumbles but will not heat? nP is almost always a half-tripped breaker or outlet issue — our technicians verify before recommending any dryer parts. Book power diagnosis.