Dryer No Heat Traced To Tripped Half Of 240 Cross System Decision Tree

Why this matters

An electric dryer that tumbles normally but never heats is the textbook lost-leg case, and the leg is lost in the panel, not in the appliance. The motor runs on 120 V from one hot leg and the neutral; the heating element needs both hot legs to make 240 V. When one half of the double-pole breaker trips, or a neutral/leg connection fails, the dryer still spins and counts down but cannot heat. Technicians who skip the receptacle reading replace a perfectly good element or thermal fuse, and the dryer comes back cold. This is a cross-system fault: the appliance is fine, the supply is half-dead.

The reason this fools people is that the dryer behaves almost perfectly. The control board, drum motor, light, and timer all run on the surviving 120 V leg, so the machine looks alive and sets no fault. Only the element circuit, which spans both legs, sees the missing voltage. The single most common version is a double-pole breaker that trips on one pole only, leaving the other pole closed and feeding the motor. A meter at the receptacle settles it in under a minute, before any panel comes off the dryer.

Symptom presentation

Drum turns, drum light and timer work, air moves, but the clothes never warm and the exhaust stays at room temperature. No fault code on most units because the control sees 120 V and runs happily. The customer often reports it started after a storm, a panel event, or a high-draw appliance on the same panel tripping. A half-tripped double-pole breaker is the classic trigger.

Quick checks

• Confirm the cycle calls for heat (not Air Fluff / Air Dry).
• With the dryer off and unplugged, inspect the cord and receptacle for heat damage or loose terminals.
• Meter the receptacle: each hot leg to neutral should read about 120 V, and hot-to-hot about 240 V. This single reading is the whole diagnosis.
• At the panel, check the double-pole breaker. A breaker can trip on one pole and look closed while delivering only one leg; cycle it fully OFF then ON.
• Confirm the neutral and ground are landed at the receptacle and the cord type matches (3-wire vs 4-wire).
• Look at the breaker tie bar. A genuine double-pole breaker trips both poles together; a pair of single-pole breakers handle-tied can trip independently, which produces exactly this single-leg-loss symptom and is a code concern in its own right.
• If the leg returns on reset but trips again under load, note the timing. An immediate re-trip points to a hard short downstream; a delayed trip after the element energizes points to a marginal breaker or a high-resistance, heating connection.

Isolation tree

Branch A: Receptacle reads 120 V on one leg, 0 on the other, ~120 V hot-to-hot.

• One leg dead -> cross-system supply fault. Causes: half-tripped double-pole breaker, a failed breaker pole, a loose or burned hot connection at the breaker or receptacle, or a feeder fault. Reset the breaker fully; if the leg returns, watch for re-trip. If it stays dead, the fault is in the panel/wiring. Refer to a licensed electrician.

Branch B: Receptacle reads 240 V hot-to-hot, both legs good.

• Supply is fine. The fault is in the appliance: open heating element, open thermal fuse or limit (usually tripped on airflow), or control. Ohm the element and thermal fuse with power off.

Branch C: Receptacle reads low or unstable on both legs.

• Loose neutral or feeder problem -> refer to electrician; do not band-aid at the dryer.

Branch D: One leg good intermittently, heat comes and goes.

• Loose connection at breaker or receptacle, or a dryer cord terminal backing out -> tighten/replace the connection point that is arcing.

Confirming diagnosis

The receptacle meter reading is conclusive. Two good legs (about 120 V each leg-to-neutral, ~240 V hot-to-hot) move the fault into the dryer; one dead leg (one leg reads 120 V, the other 0, and hot-to-hot reads ~120 V instead of 240) proves the supply. Confirm the breaker by fully cycling it OFF then ON and re-metering; a leg that returns and holds was a tripped pole, a leg that stays dead is a panel/wiring fault for the electrician. If both legs read good at the receptacle but the dryer still will not heat, open the dryer and ohm the element (continuity, typically in the low tens of ohms) and the thermal fuse and high-limit (each should read continuity; an open thermal fuse means it tripped, usually on restricted airflow that must be corrected). Document both leg-to-neutral readings, the hot-to-hot reading, the breaker behavior, and any element/thermal continuity results. That record cleanly separates "supply, refer to electrician" from "appliance element/thermal/control."

Remediation

• Half-tripped breaker that resets and holds: restore service, but investigate why it tripped (a marginal or failing breaker often re-trips). Recommend evaluation if it recurs.
• Dead leg from a panel/feeder/receptacle fault: refer to a licensed electrician for breaker replacement or wiring repair.
• Burned or loose receptacle/cord terminals: replace the receptacle or cord, re-meter both legs.
• Confirmed appliance fault (two good legs): replace the open element, thermal fuse, or limit; correct any airflow restriction that tripped the thermal device.

Re-verify by re-metering both legs at the receptacle, then running a heated cycle and confirming rising exhaust temperature and dry clothes.

References

• NEC (NFPA 70), Article 240 (overcurrent protection) and Article 250 (grounding/neutral) - 120/240 V dryer branch-circuit requirements.
• NEC (NFPA 70), Article 422 - appliance branch-circuit and cord/receptacle requirements.
• UL 2158, Standard for Electric Clothes Dryers - appliance construction and safety basis.
• AHAM - household dryer installation and electrical-supply guidance.