Watermill shower pump 3bar blowing out fuses

[yorkshire32]

Hi All,
I have just replaced our old Aqualisa shower pump 3bar with brand new Watermill heavy duty brass shower pump- 3 bar twin impeller.
it was almost straight swop. I followed the instruction accordingly and decommissioned the system etc
I turned on the power supply and asked my son to turn the shower on.
shower made a click noise then the fuse blown without turning the pump on at all!! Tried with new fuse and it keeps blowing the fuses.
Any advise will be greatly appreciated.
Thanks
Regards

 

[ban-all-sheds]

Either the pump or your wiring is faulty.

 

[yorkshire32]

I have done some other tests and wiring seems to be ok. The impeller is seized. May be I have end up up with a doggy unit.
planning to take it back tomorrow.
Thanks anyway