A breaker that trips the moment a dryer starts is usually telling you that the circuit is seeing more current than it should, or that there is a fault somewhere in the wiring or appliance. The start-up moment is when a dryer can draw its highest load, so if the breaker is already weak, the circuit is overloaded, or there is resistance building up somewhere, that is often when the problem shows up first.
One common cause is a worn or failing breaker. Breakers do age, and if one has been tripping repeatedly over the years, it can become overly sensitive. Another possibility is that the dryer is sharing a circuit or the circuit is not actually sized correctly for the appliance. Most electric dryers need a dedicated 240-volt circuit, and if anything else is tied into that line, even accidentally, it can push the breaker over the edge.
A loose connection is another big one. If the outlet, terminal block, breaker, or wiring connections have loosened, the extra resistance can create heat and a voltage drop, which can make the dryer struggle at startup and trip the breaker. This is especially worth checking if you ever notice a buzzing sound, a hot outlet, a burnt smell, or discoloration around the plug or receptacle.
The dryer itself can also be the problem. A failing motor, seized drum rollers, a bad belt, or a short in the heating system can all increase the load. If the drum is hard to turn by hand, the motor has to work harder at startup, and that surge can be enough to trip the breaker. If the tripping happens only when the heat is on, the heating element or its wiring could be involved instead of the motor.
What I’d check first is whether the breaker size matches the dryer specs, whether the circuit is dedicated, and whether the plug, cord, receptacle, and breaker connections look secure and clean. If the breaker feels hot, trips instantly, or shows any signs of damage, stop resetting it over and over. That is a case where a qualified electrician or appliance technician should take a look, because repeated tripping can point to a fire risk. If you’ve seen this before, the best advice is to start with the circuit and connections before assuming the dryer itself is bad.
