Strange issue with RCD

[Crossy]

4 minutes ago, itsari said:

I have removed the bonding and tried the RCD with a negative result even with all the breakers off.

 

 

OK, now it gets harder. Please take great care!!

 

First check with your meter that you have a high resistance between the N bar and the E bar (power off of course)

Assuming that's OK.

 

Disconnect about half of the blue wires from the neutral bar and then try the RCD.

If it stays on, then connect the blue wires one by one until it doesn't (ideally you should use an insulation tester, but one assumes you don't have one).

Otherwise pull the remaining blue wires, hopefully with them all off the RCD stays on.

 

You are trying to isolate which neutral has an issue to earth. 

 

So, connect your blues one by one, trying the RCD each time. Hopefully you will end up with one that trips the beast.

"All" you have to do then is check that circuit for damp / ants / rat damage etc.

 

 

 

 

. 

[itsari]

8 minutes ago, Crossy said:

 

 

OK, now it gets harder. Please take great care!!

 

First check with your meter that you have a high resistance between the N bar and the E bar (power off of course)

Assuming that's OK.

 

Disconnect about half of the blue wires from the neutral bar and then try the RCD.

If it stays on, then connect the blue wires one by one until it doesn't (ideally you should use an insulation tester, but one assumes you don't have one).

Otherwise pull the remaining blue wires, hopefully with them all off the RCD stays on.

 

You are trying to isolate which neutral has an issue to earth. 

 

So, connect your blues one by one, trying the RCD each time. Hopefully you will end up with one that trips the beast.

"All" you have to do then is check that circuit for damp / ants / rat damage etc.

 

. 

OK, thank you again , I will try tomorrow what you suggest as i need to keep the power on to the house for now .

Dampness and rats are not an issue . 

Thank you for your time , I appreciate your help.

Edited December 24, 2023 by Crossy
Fixed the quote

[Crossy]

4 minutes ago, itsari said:

Dampness and rats are not an issue . 

 

I really wouldn't be so sure, but let's isolate which circuit has the problem.

[PJHassselt]

It looks like Itsari took over my post..... I hope my post help him to solve his problem....

 

To answer some initial questions:

 

• In the past it worked OK.
• The problem started after heavy rain.
• So damp inside the box where the pump is connected can be an issue.
• Every circuit in my house is equipped with its own RCD. The main breaker does not have a RCD.
• I understand the RCD opens when it is dampy.
• I understand the RCD stays closed when I change the power supply from grid to my own inverter.
• I do not understand, and that was my question, when I run just a very short time on my own inverter,  (a few seconds is enough) the breaker stays closed (ON).
• We hire sometimes a very capable electrician (capable as far as I can judge) and he has also no clue.....

Best regards.

[Crossy]

1 hour ago, PJHassselt said:

It looks like Itsari took over my post..... I hope my post help him to solve his problem....

 

To answer some initial questions:

 

• In the past it worked OK.
• The problem started after heavy rain.
• So damp inside the box where the pump is connected can be an issue.
• Every circuit in my house is equipped with its own RCD. The main breaker does not have a RCD.
• I understand the RCD opens when it is dampy.
• I understand the RCD stays closed when I change the power supply from grid to my own inverter.
• I do not understand, and that was my question, when I run just a very short time on my own inverter,  (a few seconds is enough) the breaker stays closed (ON).
• We hire sometimes a very capable electrician (capable as far as I can judge) and he has also no clue.....

Best regards.

 

Oops, sorry about that.

 

I suspect your RCD is right on the brink trip wise, possibly there's a switch-on surge that pushes it over the edge but running on inverter softens that or maybe lack of a N-E bond in the inverter just defeats the RCD for long enough.

 

Is it just one circuit that trips? What's on that circuit?

 

[PJHassselt]

I have all circuits separated. On this circuit is only the fish pond.

 

And only this circuit trips 

 

Probably I should start a new topic? And let Itsari use this topic?

 

Kind regards, and thanks for help!!

[PJHassselt]

@itsa

 

Thank you, and I hope you can solve your problem fast!

 

Maybe next time start your own topic??

 

Kind regards.

[Crossy]

9 hours ago, PJHassselt said:

I have all circuits separated. On this circuit is only the fish pond.

 

And only this circuit trips 

 

Probably I should start a new topic? And let Itsari use this topic?

 

Kind regards, and thanks for help!!

 

If it's isolated down to the pond the it should be "reasonably" easy.

 

Check everything is dry of course.

I've had submersible pumps leak and start tripping the RCD, the only fix then is a new pump I'm afraid.

 

[PJHassselt]

1 hour ago, Crossy said:

 

If it's isolated down to the pond the it should be "reasonably" easy.

 

Check everything is dry of course.

I've had submersible pumps leak and start tripping the RCD, the only fix then is a new pump I'm afraid.

 

Even when the pump is unplugged the RCD trips.

 

The position from the floating switch does not matter.

 

Last night heavy rain the whole night. The thing is still on...

 

But can you explain that when it trips, even very short running of my inverter can solve this for something like 24 hour?

 

Thanks, and regards!

[Crossy]

33 minutes ago, PJHassselt said:

But can you explain that when it trips, even very short running of my inverter can solve this for something like 24 hour?

 

From my earlier post: -

I suspect your RCD is right on the brink trip wise, possibly there's a switch-on surge that pushes it over the edge but running on inverter softens that or maybe lack of a N-E bond in the inverter just defeats the RCD for long enough.

 

The above is pure speculation based upon experience, but I really don't know exactly why you are seeing this. So, we just have to use the scatter-gun approach, eliminating the easy stuff first.

 

To actually measure the leakage current requires some specialist equipment (a low reading AC clamp ammeter).

 

You may find that simply swapping the RCD with another will solve the issue. The requirements for an RCD are that they must NOT trip at 50% of the rated current and that the MUST trip at 100% of the rated current. So, a "30mA" RCD could trip anywhere between 15mA and 30mA, a pretty big range.

 

By the way, you really shouldn't be running your inverter with no N-E bond (or at least an earthed neutral - but check the manual) as it defeats downstream RCDs.

 

[carlyai]

If the tripping RCB only feeds the pump, how does the float switch get its power?

If the float switch is one that the sealed contacts actually float in the tank, these can leak. 

If the float switch is on that tripping RCB, maybe disconnect the feed to it and see what happens.

[Crossy]

Also, is your feed to the pond area underground? Isolate it where it emerges and test (maybe run a temporary above ground feed).

 

[PJHassselt]

On 12/25/2023 at 7:46 AM, carlyai said:

If the tripping RCB only feeds the pump, how does the float switch get its power?

If the float switch is one that the sealed contacts actually float in the tank, these can leak. 

If the float switch is on that tripping RCB, maybe disconnect the feed to it and see what happens.

I wrote: "the tripping circuit only feeds the fish pond"

 

There are more things in the pond. Like type floater switch (it is from the kind with two floating "things" When two are submersed the switch switches, and when two are free from the water the switch switches. The switch itself is above the water. When I disconnect all, so this switch, the pump, and an "Atomizer" the RCD still opens.

[PJHassselt]

On 12/25/2023 at 8:02 AM, Crossy said:

Also, is your feed to the pond area underground? Isolate it where it emerges and test (maybe run a temporary above ground feed).

 

All cables are "in the air" 

[PJHassselt]

On 12/25/2023 at 6:56 AM, Crossy said:

 

From my earlier post: -

I suspect your RCD is right on the brink trip wise, possibly there's a switch-on surge that pushes it over the edge but running on inverter softens that or maybe lack of a N-E bond in the inverter just defeats the RCD for long enough.

 

The above is pure speculation based upon experience, but I really don't know exactly why you are seeing this. So, we just have to use the scatter-gun approach, eliminating the easy stuff first.

 

To actually measure the leakage current requires some specialist equipment (a low reading AC clamp ammeter).

 

You may find that simply swapping the RCD with another will solve the issue. The requirements for an RCD are that they must NOT trip at 50% of the rated current and that the MUST trip at 100% of the rated current. So, a "30mA" RCD could trip anywhere between 15mA and 30mA, a pretty big range.

 

By the way, you really shouldn't be running your inverter with no N-E bond (or at least an earthed neutral - but check the manual) as it defeats downstream RCDs.

 

Many, many years ago you told me that it is normal an inverter does not open a RCD, you explained with a story from your teacher, who touched (if I remember correct) a three phase power supply, connect through a separation transformer.

 

It is really many years back, but that made me still thinking it is normal my inverter does not let the RCD's trip.....

 

Regards.

[Crossy]

That would have been Mr (Fray Bentos) Bentley.

 

Much depends upon your inverter, hence my comment to read the manual. A modern solar inverter will be happy to have the neutral earthed, older inverters may not be so happy and certainly a UPS shouldn't have random earths scattered around.

 

Anyway, to the current issue. You need to isolate each individual component to verify that the tripping goes away, of course this will be easier said than done if the tripping is random.

 

Try feeding just the pump from an extension from another outlet, do things trip?

Continue similarly until the tripping stops and suspect whatever you disconnected last.

Without the correct test gear, it's not going to be easy

 

 

[Crossy]

Unfortunately, the "proper kit" 'aint cheap

 

https://www.lazada.co.th//products/i1590628701-s9904969029.html