Hi all

posted this in another subforum here, but did not get any responses. Maybe here it will get more attention 🙃

I am out of ideas - so I am hoping one of you here will be able to help.

The earth on my essential DB trips, but only under certain circumstances. Here the facts as best as I can describe:

• The trips only occur when I am connected to the grid. When I am off-grid, everything runs without problems for weeks
• I have a 63A single-pole smart breaker installed in-between my grid main breaker and my inverter AC In. I use this to disconnect myself from the grid and only re-connect when required (when I see that my PV/batteries will not be sufficient to get me through the day)
• The trips only occur during night-time and early morning. From what I can remember, the earliest trip was around 01h00 and the latest around 07h00
• The trips almost always occur in the 1st night after re-connecting to grid. E.g., last time I re-connected around 23h00 before going to bed and at 01h00 the trip occurred
• The trip is caused by a single circuit. If I flip the earth leakage breaker back on after it has tripped, it immediately trips again (within 30s). If I switch off the circuit breaker for the circuit in question and then switch on the earth leakage breaker again, everything runs stable
• The circuit in question consists of a few plugs inside the house as well as 2 inverter aircons
• The trips occur independent of any circuit (e.g., happens whether any or both aircons are on or off)
• I have physically disconnected everything from the plugs - the trips still occur

I used to have a relay for my earth bond, which my electrician in the meantime has replaced with a permanent bond. The trips occurred with the relay in place (and working) and persist now that I have a permanent bond.

Do any of you have any ideas on what might cause this and how I can fix it?

Is the breaker feeding the inverter also connected to the E/L. If it is, change it.

13 minutes ago, Jacques Ester said:

Is the breaker feeding the inverter also connected to the E/L. If it is, change it.

Not to the one that is tripping

I have an E/L on my main DB, which feeds the AC In of the inverter. That E/L is not tripping

I have an E/L on my Essentials DB, which is fed from the AC Out of the inverter. This one is tripping

It is normally the upstream E/L that trips but just maybe remove the inverter supply from E/l and test.

While it may be a different situation, we had a similar situation where the E/L of a section of the building trips constantly when reconnecting to grid. For us it looks like there was a minor earth fault, however, it looks like someone ran grid and inverter supply to the same circuit and while it didn't blow anything since the inverters synced to that supply it caused harmonics issues and tripping issues....

34 minutes ago, Jacques Ester said:

It is normally the upstream E/L that trips but just maybe remove the inverter supply from E/l and test.

Ok - thanks

Will give that a try

16 minutes ago, Psy said:

it looks like someone ran grid and inverter supply to the same circuit and while it didn't blow anything since the inverters synced to that supply it caused harmonics issues and tripping issues

Can you please help me better understand what you mean by 'ran grid and inverter supply to the same circuit'?

And what did you do to fix it?

It can also be a oversensitive E/L. 

1 minute ago, Jacques Ester said:

It can also be a oversensitive E/L. 

Thnx - also thought of that. Had that problem on my Main DB in the past. Replaced it and the trips there stopped.

But the E/L on the Essentials DB is relatively new (2 years or so).

And what I find strange that it is only the single circuit that is tripping it

39 minutes ago, wolfandy said:

Can you please help me better understand what you mean by 'ran grid and inverter supply to the same circuit'?

And what did you do to fix it?

I think what he means is that the circuit wasn't properly spilt between essential and non essential. It can happen that the live is feeding from the inverter and the neutral is connect to the Eskom fed side. This creates an unbalance and trips the E/L.

Edited January 9, 20232 yr by Jacques Ester

3 minutes ago, wolfandy said:

Can you please help me better understand what you mean by 'ran grid and inverter supply to the same circuit'?

And what did you do to fix it?

Basically, one section of the building was connected to both sides of the change-over before we got there... The Essentials and non-essentials weren't separated properly and while it was only Neutral (So the circuit isn't powered up if you turn the inverter on but half of it is still connected to grid earth) it was enough to cause endless headaches. Just double check the circuits on that E/L to make sure you don't have grid and inverter connected at the same time.

Thnx @Jacques Ester and @Psy

Will have my electrician check

1 hour ago, wolfandy said:

Thnx - also thought of that. Had that problem on my Main DB in the past. Replaced it and the trips there stopped.

But the E/L on the Essentials DB is relatively new (2 years or so).

And what I find strange that it is only the single circuit that is tripping it

And what I find strange that it is only the single circuit that is tripping it.

I'm no electrician but it sounds to me that that circuit or something that is plugged into it has an intermittent earth fault. I had a small bar fridge that was causing  occasional tripping.

3 hours ago, Thunderdolt said:

I'm no electrician but it sounds to me that that circuit or something that is plugged into it has an intermittent earth fault. I had a small bar fridge that was causing  occasional tripping.

Thnx

Other than the 2 inverter aircons (hardwired), I have already unplugged everything from the sockets on that circuit - but still got trips.

The only other thing I still want to do is open up every socket on that circuit and check for loose connections

Aircons?? hmmm.🙂 Do hardwired aircons need to be behind rcd's? Maybe a sparky can elaborate.

Depending on how many sockets you have isn't it quicker to disconnect one or both aircons?

1 hour ago, Thunderdolt said:

Do hardwired aircons need to be behind rcd's? Maybe a sparky can elaborate.

They are a 9000 and a 12000 BTU inverter aircon. According to my sparky they are allowed to be hardwired to a plug circuit.

1 hour ago, Thunderdolt said:

Depending on how many sockets you have isn't it quicker to disconnect one or both aircons?

I have already opened up the outside box with the manual on/off switch for each aircon and have checked connections. Have also switched off the aircons there - but still trips occur. The only thing on the aircons I have not checked is the actual connection into the aircon unit (from the manual on/off switch)

you may find it is the light circuit. Do you have that going through the EL? Light circuits apparently do not reside behind EL anymore as modern lights cause issues with the EL. Probably the most unsafe thing I can think of but I confirmed it with my electrician. Wired correctly. So perhaps check if the lights are wired through the EL on the inverter side. This caused issues at my dad's installation. 

8 minutes ago, JTK said:

you may find it is the light circuit. Do you have that going through the EL?

Thnx. But no, lights are not on E/L

20 hours ago, wolfandy said:

They are a 9000 and a 12000 BTU inverter aircon. According to my sparky they are allowed to be hardwired to a plug circuit.

Yes it is correct as long as the plug is within a short distance and thus dedicated to that specific plug. 

Brief udpate:

Had my sparky here today and confirmed that separation between Main DB and Essential DB is correct. Other than inverter feed, only 3 other circuits left on Main DB (which are all switched off)

Installed a new E/L (Schenker). 

After the install, switched everything on except for the problem circuit. Everything working. Flipped on the last circuit breaker - and within 10 seconds the E/L tripped 😞

First time that I had the trip during daytime and while disconnected from Eskom. So I guess the new E/L is even more sensitive than the old one

Opened up the socket to which the aircons are hardwired and checked connections. Found that the connection for the neutral going to the aircons might potentially have been a bit weak. Re-did all connections

Flipped the circuit breaker on again - and everything worked. Problem solved?

Fast-forward by 2 hours: E/L trips again. Switch off circuit in question and put E/L in again. Everything works. So the connection on the aircon feed does not seem to have been the problem...

Have now physically disconnected the feed to the aircons from the circuit

Everything running again at the moment. Will monitor what happens

Ask your sparky to do a megger test on that specific circuit wiring. It may be that there is something wrong with the insulation.

13 minutes ago, Scorp007 said:

Yes it is correct as long as the plug is within a short distance and thus dedicated to that specific plug. 

Thnx. Around 2m to the 1st aircon and then another 3m to the 2nd one.

Have to admit I only realized today that they are wired in series. I thought the 2nd aircon was wired into a different socket in the same circuit

3 minutes ago, Jacques Ester said:

Ask your sparky to do a megger test on that specific circuit wiring. It may be that there is something wrong with the insulation.

Thnx. Will do when he is here next

20 minutes ago, wolfandy said:

Thnx. Around 2m to the 1st aircon and then another 3m to the 2nd one.

Have to admit I only realized today that they are wired in series. I thought the 2nd aircon was wired into a different socket in the same circuit

assume you mean in parallel...?

9 minutes ago, JTK said:

assume you mean in parallel...?

I have to admit that I have to open up all boxes again to confirm. But from I can judge from the trunking I assume the following:

[Inside socket] - wire - [Manual switch inverter 1] - wire - [Manual switch inverter 2]

I assume that the wire from switch 1 to switch 2 is connected to the In on switch 1