Motors & overloads
Won't start, tripping overloads, and running faults.
Motor overload keeps tripping
The thermal/electronic overload trips repeatedly, either on start or after the motor has run for a while. Resetting only buys you a short run before it trips again.
Motor won't start and makes no sound at all
Press start and nothing happens — no hum, no movement, no attempt to turn. The motor is completely dead rather than struggling.
Motor hums but won't start to turn
On start the motor hums or buzzes but won't rotate — it may draw heavy current and trip protection. Often a sign it's only getting two phases or is mechanically locked.
Motor running hot / overheating
The motor runs but gets excessively hot — too hot to touch, smell of hot insulation, or thermal protection cutting in after a while.
Motor noisy or vibrating (bearing / mechanical)
The motor runs but is noisy, rough, or vibrating — grinding, rumbling, or whining noises that point to bearings or mechanical trouble.
Motor with low insulation resistance to earth
An insulation resistance test on the motor reads low to earth — a sign the winding insulation is degraded, damp, or contaminated, risking trips and failure.
Soft starter faulting or not ramping the motor
A soft starter won't ramp the motor up smoothly — it faults out, the motor jerks or doesn't reach full speed, or the bypass doesn't engage.
Motor trips protection on start but runs fine if it gets going
Protection trips during the start/inrush, but on the rare occasion it gets running it's fine — pointing at starting current, settings, or load inertia rather than a running fault.
Motor runs in the wrong direction
The motor runs but the wrong way — pump runs backwards, fan blows the wrong way, conveyor reverses. Usually a phase-rotation issue after wiring or supply work.
Motor draws fluctuating current / unstable running
The motor runs but its current swings up and down, speed surges, or it runs roughly — pointing at load variation, supply, or control instability rather than a hard fault.
Air compressor won't start or keeps cutting out
The workshop compressor hums without starting, trips its overload or the breaker, or starts and cuts out before reaching pressure. Nearly always one of four things: start capacitor, pressure switch/unloader, head pressure it can't start against, or a supply that sags.
Pump motor runs but there's no flow
The pump motor runs normally electrically, but there's little or no flow/pressure — the electrics are fine, so the problem is hydraulic, priming, or direction.
Motor overload trips after running for a while
The motor starts and runs fine, then the thermal overload trips minutes or hours later. Reset it and it runs again before tripping once more — a heat/loading pattern, not a start fault.
Three-phase motor single-phasing while running
A running three-phase motor loses one phase. It keeps turning but loses torque, draws heavy unbalanced current, gets hot and noisy, and often trips the overload — but won't restart if stopped.
Star-delta starter trips the overload at the star-to-delta changeover
The motor starts fine in star, but at the moment it switches to delta the overload (or breaker) trips. Stays running if it survives the transition; trips reliably on the changeover.
DOL starter won't latch when you press start
Press start on a direct-on-line starter and nothing latches — the contactor doesn't pull in at all, or pulls in and immediately drops. The motor never runs.