Submersible Pump blowing breakers

[Psyclist]

Hi all,

I've had a submersible pump in a small hole in the floor in our cellar for just over a year and last week it just suddenly started tripping the fuses.

It's just a normal 240v puddle pump (http://www.clarkeservice.co.uk/manuals/submersible_water_pumps/psp125.pdf) and it's plugged into a socket on the main ring.

At first it was blowing the ring MCB (Square D C32 RCBO) and by the time I managed to get down there to have a look, it was going beyond that and blowing the 3-phase RSD (Square D 80A RCCD) which supplies the entire section board that powers our 3-phase plant, room lights and the relevant socket ring.

Fortunately I had a spare pump, so I just switched the pump over and everything's fine now, but in order to return the pump for inspection they're asking me to tell them what the problem is with it first which seems a little strange to me. I've got an NVQ level 2 in electrical engineering and my 17th edition, but I don't have the experience to be able to guess at what the likely problem is, but they're saying because we're a commercial premises they want to know what the fault is with the pump before they'll give me a postage slip for returning it to them. I can only assume they must have different places for returning different faults to, but I would have assumed electrical is electrical...

Regardless, I'm a little perplexed so just wondered if anyone could even give me a brief idea of what might be the issue and I'll just pass that on to them and hopefully get it sent off as soon as possible.

Cheers!

[EDIT] I should probably add that it blows the breakers as soon as the socket is switched on even though the internal switch on the pump is in the off position and I've tried it in a different socket to make sure it isn't just the socket. I'm guessing it's somehow developed a short, but I realise it's not always as simple as that hence I'm here and asking.

 

[winston1]

It is tripping RCDs not breakers. Tell them it's an insulation fault tripping the RCD.

 

[Psyclist]

Sorry that's me calling them the wrong thing.

So you reckon it's an insulation fault? I'm guessing it's possible that could happen inside the unit then because I've had the plug apart and everything seems fine and the cable is still in the same condition it came in, so it has to be something inside the casing as far as I can see.

 

[Robin0577]

Most likely a seal or gasket is leaking somewhere and water is getting into the bits that are supposed to be dry. That would certainly render the insulation faulty.

 

[Psyclist]

Great! I'll get onto them this afternoon and hopefully get around them trying to wriggle out of sorting it out.

Appreciate your help guys!

 

[EFLImpudence]

Sorry that's me calling them the wrong thing.

No you weren't - RCDs are breakers as well, RCCB & RCBO.

 

[Taylortwocities]

When you did your NVQ, did you remember the lessons about Insulation Resistance Testing?

You need an Insulation Resistance Tester, then yoiu can determine that there is really a fault beween the earth and one of the live connections.

 

[Psyclist]

Yeah that's the thing though I don't have an insulation tester. Might see if I can find a reasonably priced second hand one and slip it into my kit list.

 

[ekmdgrf]

I think that you may be reading too much into what the manufacturer have asked. I would interpret "tell us what the fault is" as "what are the symptoms" rather than "take it to bits and identify the failed component".

As previously stated almost certainly water has leaked into the pump and is leaking to earth where the flex connects to the switch.

That's far more effort than the manufacturer is going to put into identifying the fault. It's just not worth trying to fix something that cost £50. Better to give you a cheque and throw it in the bin. If you're really unlucky, they might just plug it in to see if it powers on. In which case, point out that they should test it with a RCD on the circuit and then see what happens. Also remind them that it says in the instructions not the run the pump out of water, even for a test...

 

[stillp]

They just need something to put on the paperwork. Just say it has an insulation fault.

 

[Norcon]

Most submersibles go the same way. Had a flash bang in the face with one last year when the cable frayed and water ingressed.
If they had any brains they would use a "plug it" type connection. Same as festool only water proof.
So a breach on the cable sheathing can never channel water into the pump motor.

 

[conny]

Just tell them it keeps tripping the RCD, MCB, RCBO or whatever.

You do not need to tell them anything other than that. It will take a motor repair man to decide what the actual problem will be.