Overload relay won't reset
After an overload trip, the reset won't take — the starter won't re-arm, or it resets and trips straight back. The control circuit stays broken at the overload's contact.
Safety first
An overload that won't reset is often still protecting against a real fault. Don't force it; resetting can restart machinery — confirm it's safe first.
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
Not enough cool-down time (thermal type)
Most likelyA thermal overload needs time to cool before it will reset after a trip.
- 2
Underlying fault still present
#2If the cause (jam, single-phasing, overcurrent) is still there, it resets then trips immediately.
- 3
Reset set to manual/auto incorrectly
#3The reset mode (hand/auto) is set wrong for the application, so it doesn't behave as expected.
- 4
Mechanical fault in the reset mechanism
Least likelyA damaged reset button or trip mechanism won't latch back even with no fault.
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.
Allow a thermal overload to cool, then attempt the reset.
It resets cleanly once cooled.
It was just cool-down — done, but note why it tripped.
Still won't reset or trips again — investigate further.
View all expected readings at once
Fault-finding flowchart
The same logic as a decision tree.
- 1start
Overload won't reset
→ step 2 - 2decision
Does it reset after cool-down?
Yes→ step 3No→ step 4 - 3decision
Does it hold with balanced, in-rating current?
Yes→ step 5No→ step 6 - 4decision
Is the reset mode correct and mechanism sound?
Yes→ step 7No→ step 8 - 5result
One-off trip — monitor; note the original cause.
- 6result
Trips again — chase the real overload (jam/single-phasing/overcurrent).
- 7result
Re-examine the load — something is still tripping it.
- 8result
Correct the reset mode / replace a broken mechanism.
Common mistakes apprentices make
- Hammering the reset before a thermal overload has cooled.
- Resetting repeatedly into a real fault instead of finding it.
- Not knowing whether the overload is set to hand or auto reset.
- Condemning the overload when the load is genuinely overloaded.
When to stop & escalate
If it trips again on reset with high or unbalanced current, stop and find the load/supply fault before re-energising. A broken reset mechanism means replacing the overload.
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
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.
Contactor contacts welded closed — load won't switch off
The contactor won't drop out when the coil is de-energised. The load stays powered even with the control circuit off, because the main contacts have welded together.
Learn the theory
How the gear and circuits behind this fault actually work.