Safety first: Only qualified persons should open electrical panels. Isolate power at the main breaker before removing covers.

Verify three-phase supply: With a multimeter, measure voltage between all three phases (L1-L2, L2-L3, L1-L3) at the Calpeda control box input. All readings should be within 5% of the rated voltage and similar to each other.
Check fuses and breakers: Inspect individual phase fuses or miniature circuit breakers feeding the pump. Replace any blown fuses with the correct rating specified by Calpeda.
Inspect terminal tightness: With power off, tighten all screw terminals on the incoming supply and motor output terminals in the Calpeda terminal block. Loose connections can cause phase loss and overheating.
Check contactor: Inspect the contactor for burned contacts or a stuck pole. If one pole is not closing, replace the contactor with an equivalent Calpeda-approved model.
Reset controller: After correcting the supply issue, reset the controller according to the Calpeda manual (usually by pressing STOP/RESET for several seconds) and attempt a restart.

If phase loss persists, consult an electrician to investigate upstream supply issues.

Controller shows E03 and pump does not start, sometimes after a power outage

Possible Causes