Level of water in sumps is too high
Impeller damaged
Pump is running in reverse direction
Motor running fast due to higher frequency
Initial cost high
Diameter is small
Requires skill for erection
In case of defect entire unit is to be lifted
Very costly
Motor and pump are submerged in water
Motor and pump are connected through metal pipes
copper
brass
eureka
nichrome
flat nichrome
tungsten
manganin