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.
Safety first
A 'dead' motor circuit can still have live terminals. The motor may also start the moment a missing condition is restored. Prove dead before working at the terminals.
Isolate, lock out / tag out, and prove dead before working unless a live test is specifically required, authorised, and carried out under proper supervision. Always follow local regulations, your site procedures, and the equipment manufacturer's documentation.
Full detail — causes, the why, and common mistakes.
Likely causes
Ranked from most to least likely.
- 1
No supply reaching the motor (upstream open)
Most likelyA tripped breaker, open isolator, blown fuses, or a contactor not closing means no power reaches the motor at all.
- 2
Control circuit not completing
#2The start command never energises the contactor — faulty start button, e-stop, overload contact, or control supply.
- 3
All-phase loss vs single-phasing
#3Total silence usually means all phases are gone (not single-phasing, which normally hums) — points upstream.
- 4
Open motor connection / broken supply cable
Least likelyA broken cable or disconnected terminal between the starter and motor removes power entirely.
Reports are saved on this device to reflect what you actually find.
Testing sequence
Work through one test at a time. Expected reading and what each result means.
Press start and check whether the main contactor energises (clunk / coil voltage).
Contactor pulls in on the start command.
Contactor closes — check for supply through it to the motor.
Contactor doesn't close — the fault is in the control circuit.
View all expected readings at once
Fault-finding flowchart
The same logic as a decision tree.
- 1start
Motor dead, no sound
→ step 2 - 2decision
Does the main contactor energise on start?
Yes→ step 3No→ step 4 - 3decision
Is supply present through to the motor terminals?
Yes→ step 5No→ step 6 - 4decision
Is the control path (button/e-stop/overload) complete?
Yes→ step 7No→ step 8 - 5result
Power reaches a dead motor — inspect the motor/connection.
- 6result
Check fuses, isolator, and the contactor main contacts.
- 7result
Path complete, coil won't pull in — see contactor coil fault-finding.
- 8result
Open in control path — e-stop, overload, or button. Repair it.
Common mistakes apprentices make
- Assuming the motor is burnt out when it's simply getting no supply.
- Skipping the control circuit and focusing only on the power side.
- Not noticing an e-stop or overload contact is open.
- Forgetting that total silence usually means all phases gone, not single-phasing.
When to stop & escalate
If supply is missing upstream (incoming or distribution), escalate to that level. If power reaches a dead motor, plan a motor inspection/insulation test before condemning it.
If you're past your competence, authorisation, or the safe limits of the job — stop and hand it on. There's no fault worth getting hurt over.
Related faults
No control voltage in the panel
Nothing in the control circuit will operate — contactors won't pull in, indicators are dead, the PLC may be off. The control voltage that should be there simply isn't.
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.
Three-phase equipment single-phasing (lost a phase)
Three-phase equipment is misbehaving — motors humming, struggling, overheating, or tripping — because one phase has been lost somewhere between the supply and the load.
Learn the theory
How the gear and circuits behind this fault actually work.