humagiyo
New User
- Location
- Cummington
- Occupation
- Electrical Contractor
I have a submersed bore pump 85M down and covered by 40M water. The motor/pump is 1.1HP, capacitor run, 35uF in a capacitor box above ground, with a three wire conductor and earth cable going to the pump. The water is pumped up into a tank at ground level. There is a pressure switch at the ground level outlet to shutoff if the water supply in the bore goes dry.
It has worked without incident for about five years. However for the last few months I have had intermittent rcbo trips back in the meter box. Now the failures are getting more frequent. There are two underground feeds each fed by their own rcbo. Currently the motor runs for about ten seconds and trips. I can reproduce the fault exactly the same each time. It does not matter which of the underground feeds I use, the symptoms are the same for the failing motor. The other pump, in the same location, is a surface pump and it works fine regardless of which GPO it is connected to.
The pressure switch and capacitor box have been isolated with no change in symptoms. The run cap has also been changed without changing the symptoms. It runs for ten seconds then stops tripping the rcbo.
Today I ran the bore pump from my 2KW generator. It worked fine for several hours until it ran out of petrol. I suspected insulation leakage somewhere so I kept away from the generator while running etc.
I then plugged the bore pump back into the GPO and it now runs fine. It no longer trips the rcbo. The generator does not have an earth reference, no earth connection to its GPO outlet. The gpo’s and pumps and cap box are out in the weather so I am about to fit a roof over the lot. I am hoping the the problem will not recur.
I assume moisture did something and running with the genny dried it out. It’s not clear what changed. It’s unlikely the motors would ‘dry out’ when it’s 40M below water. The plug that plugs into the GPO is moulded giving little chance for water to enter the cable there. The connections at the pressure switch are water sealed by glands as is the cap box. It’s almost like there is a pin hole somewhere in the cable that lets in moisture but I can’t see how that would happen.
Has anyone had any experience with a similar fault
It has worked without incident for about five years. However for the last few months I have had intermittent rcbo trips back in the meter box. Now the failures are getting more frequent. There are two underground feeds each fed by their own rcbo. Currently the motor runs for about ten seconds and trips. I can reproduce the fault exactly the same each time. It does not matter which of the underground feeds I use, the symptoms are the same for the failing motor. The other pump, in the same location, is a surface pump and it works fine regardless of which GPO it is connected to.
The pressure switch and capacitor box have been isolated with no change in symptoms. The run cap has also been changed without changing the symptoms. It runs for ten seconds then stops tripping the rcbo.
Today I ran the bore pump from my 2KW generator. It worked fine for several hours until it ran out of petrol. I suspected insulation leakage somewhere so I kept away from the generator while running etc.
I then plugged the bore pump back into the GPO and it now runs fine. It no longer trips the rcbo. The generator does not have an earth reference, no earth connection to its GPO outlet. The gpo’s and pumps and cap box are out in the weather so I am about to fit a roof over the lot. I am hoping the the problem will not recur.
I assume moisture did something and running with the genny dried it out. It’s not clear what changed. It’s unlikely the motors would ‘dry out’ when it’s 40M below water. The plug that plugs into the GPO is moulded giving little chance for water to enter the cable there. The connections at the pressure switch are water sealed by glands as is the cap box. It’s almost like there is a pin hole somewhere in the cable that lets in moisture but I can’t see how that would happen.
Has anyone had any experience with a similar fault
