Discuss Earth fault on water pump in the Electrical Forum area at ElectriciansForums.net

Welcome to ElectriciansForums.net - The American Electrical Advice Forum
Head straight to the main forums to chat by click here:   American Electrical Advice Forum

Reaction score
6
Alright folks,
First time poster but im at my wits end! Got a mobile welfare unit which has a small 3kw hand wash in it. The water to the hand wash is fed from a small pump which comes on when the sensor for the hand wash is activated. There is a flying earth lead from the pump which is now getting between 60 and 80 volts to neutral and the same to earth. With this lead disconnected everything works as it should but obviously when i connect it it just blows fuse straight away.
Initial thought was obviously a faulty pump so changed the pump but new one is doing exactly the same. Could this be down to bad neutral or something somewhere? Im completely lost. All other cables and circuits appear to be testing out fine unless im missing something stupid.

Should also mention its all fed from an on board generator.
Hope someone can point me in right direction,
Thanks
 
I would advise you get an Electrician local to you to come and sort the problem for you, advising from a remote Forum, for something like this is ill advised, nothing like someone with eyes on the problem.
 
Afternoon Pete,
Thanks for the response. I am an electrician, with 12 years experience but have never came across a fault like this before. Was just hoping someone else might have seen something similar. Appreciate your response tho, ill maybe phone a friend ☺
 
Afternoon Pete,
Thanks for the response. I am an electrician, with 12 years experience but have never came across a fault like this before. Was just hoping someone else might have seen something similar. Appreciate your response tho, ill maybe phone a friend ☺
Ah right sorry
 
I think you need to isolate the power, connect the flylead and do some insulation resistance tests. You may well have a fault to a piece of floating exposed metalwork and by connecting the flylead you are completing the fault path. That is one possible scenario.
 
I think you need to isolate the power, connect the flylead and do some insulation resistance tests. You may well have a fault to a piece of floating exposed metalwork and by connecting the flylead you are completing the fault path. That is one possible scenario.

Thats interesting and quite possible. The fly lead wasnt connected to the main cpcs, it was onto a bolt on the metal work. Ive had enough for today but will try that tomorrow and report back.Earth fault on water pump 20190717_171534 - EletriciansForums.net
 
So the green/yellow wire is the flylead, connected into the pump? When connected to your arrowed earth stud the fuse goes?
 
So the green/yellow wire is the flylead, connected into the pump? When connected to your arrowed earth stud the fuse goes?

Yeah thats correct. And when its not connected to the earth stud and i put my meter across the green/yellow fly lead and my main earth or neutral im getting between 60 and 70 volts
 
So aside from the fly lead does the pump have another cpc.
 
What device exactly blows or trips?

If the cable is the only earth connection to the pump, when it is floating (or connected to the outside world only via the meter) the voltage is not very meaningful and tells you as much about the input resistance of your meter as it does about the pump. Reading a voltage does not in itself indicate that anything should trip, as it could be the result of a tiny and normal amount of leakage that can only find its way to earth through the meter, as the lead is disconnected from its rightful place on the earth terminal.

Note that the OP states that power comes from an on-board generator. We expect it to be TN-S but have to keep an open mind about the neutral-earth linkage situation until proven.
 
Morning guys, firstly thank you for all the help, appreciate it. Quick update this morning. Have done an IR test on the pump and thats all clear. When i do an IR test between the earth stud on the metal work and the live feed from the DB to the hand wash im getting a reading of about 0.70 so assuming the metal enclosure is actually the issue not the pump. Going to.dig a bit deeper and see what i come up with.
 
All sounds mysterious. If the fly lead earth is the source of earth for the pump I can't see how connecting to that stud would create a fault issue. Keep us posted.
 
Im struggling with that as well because when the fly lead is not connected everything works fine (except for the fact im getting a voltage on the lead ) but as soon as you connect to that stud, or any earth i imagine, it blows the inline fuse and trips rcd. Even when pump live and neutral are connected im still getting clear IR readings to the flying lead. Gonna be some serious head scratching!

Should also mention the neutral earth is linked at generator. But as nothing else is having issues im convinced its nothing to do with that.
 

Reply to Earth fault on water pump in the Electrical Forum area at ElectriciansForums.net

OFFICIAL SPONSORS

Electrical Goods - Electrical Tools - Brand Names Electrician Courses Green Electrical Goods PCB Way Electrical Goods - Electrical Tools - Brand Names Pushfit Wire Connectors Electric Underfloor Heating Electrician Courses
These Official Forum Sponsors May Provide Discounts to Regular Forum Members - If you would like to sponsor us then CLICK HERE and post a thread with who you are, and we'll send you some stats etc

Electrical Forum

Welcome to the Electrical Forum at ElectriciansForums.net. The friendliest electrical forum online. General electrical questions and answers can be found in the electrical forum.
This website was designed, optimised and is hosted by Untold Media. Operating under the name Untold Media since 2001.
Back
Top
AdBlock Detected

We get it, advertisements are annoying!

Sure, ad-blocking software does a great job at blocking ads, but it also blocks useful features of our website. For the best site experience please disable your AdBlocker.

I've Disabled AdBlock