Since having built a stand alone building next to the main house, every single time lightning strikes in the area, the earth leakage trips at the new building's DB (the new DB is fed from the main house, which is unaffected by any lighting strikes). This has been ongoing for the past 8 years and happens ONLY when lightning strikes. Is there a possible solution for this? I'm considering installing a double pole surge arrester in the DB, but not sure if this will solve the problem. Any ideas?

The earth leakage unit may be over-sensitive.

They do have varying degrees of sensitivity. Often, if installed in a string (a DB and sub-DB) one will consistently trip whilst the other is fine. Are they the same make?

 

Edited November 5, 20205 yr by PaulinNorthcliff

1 hour ago, PaulinNorthcliff said:

The earth leakage unit may be over-sensitive.

They do have varying degrees of sensitivity. Often, if installed in a string (a DB and sub-DB) one will consistently trip whilst the other is fine. Are they the same make?

 

Thanks for the reply. Yes, they seem to be the same make (CBi), but the one in the main house is a much older version (HY-MAG CBi, 60A, with test button separate for the switches) while the newer ELCB (which is tripping) is the standard CBi 63A. So what I gather is that replacing the ELCB could solve the problem, but not necessarily, since  the replacement might be just as sensitive?

47 minutes ago, Vassen said:

I had a similar problem but mine used to be affected by rain. As soon as the rain started , earth leakage in my main dB would trip. I would then turn it back on and it could rain for days and it wouldn’t trip again until it rained again on another day. In my case the EL in the second dB would be fine. 
 

I changed the old EL for a new one, exact same cbi type and problem disappeared. 

I've searched the internet and forums for a solution to no avail. It seems for some people, who had exactly the same problem with lightning, the replacement didn't even work. But I guess I will have to replace it and hope for the best. And add the surge arrester for good measure. Thanks for your reply.

4 hours ago, Jasey said:

Thanks for the reply. Yes, they seem to be the same make (CBi), but the one in the main house is a much older version (HY-MAG CBi, 60A, with test button separate for the switches) while the newer ELCB (which is tripping) is the standard CBi 63A. So what I gather is that replacing the ELCB could solve the problem, but not necessarily, since  the replacement might be just as sensitive?

Have you checked the kA ratings on both units? The lower the rating, the more sensitive the EL will be. 

I had an issue with 2 EL's in line.. Both CBI, one old one new. The 2.4kA unit was the entire phase and a 3kA unit connect to the Borehole sub DB. The Borehole would trip the phase EL on occasion and never its own EL. To test we replaced the 2.4 with a 3kA and problem solved as it was obviously just a little too sensitive. Subsequently we have taken the sub DB off the phase's EL

16 hours ago, Jay-Dee said:

Have you checked the kA ratings on both units? The lower the rating, the more sensitive the EL will be. 

I had an issue with 2 EL's in line.. Both CBI, one old one new. The 2.4kA unit was the entire phase and a 3kA unit connect to the Borehole sub DB. The Borehole would trip the phase EL on occasion and never its own EL. To test we replaced the 2.4 with a 3kA and problem solved as it was obviously just a little too sensitive. Subsequently we have taken the sub DB off the phase's EL

Thanks, Jay-Dee. The EL's are not in series. I have 3 phase power and the main house's EL (2.5 kA) is on its own phase and when it is off, only the main house's power (plugs) are off. The new house's power does come from the main house's DB on a different phase and the EL is 3kA (the main switch of the DB of the main house cuts all power on the property. Now, the new house's DB wiring has the EL connected to the geyser, stove and lights, which, as I understand isn't strictly necessary (but safer?). Had a electrician tell me that the EL was overloaded, but that doesn't explain the problem, since the EL ONLY trips with a ligthning strike in the area.

@Jasey Dont ask me how or with what tools but perhaps the resistance to earth is higher on the new building. Does the new building have it's own earth spike? Has anyone checked the resistances to ensure that the spike is working correctly. If there is no spike and you are bringing earth from the main house, you might find the losses on the cable is too high.

This was not my issue when I had our borehole issues but was one of the things that was checked at the time. They wanted to confirm that there was not a reason it was tripping before simply increasing the tolerance on the EL 

17 hours ago, Jasey said:

Thanks, Jay-Dee. The EL's are not in series. I have 3 phase power and the main house's EL (2.5 kA) is on its own phase and when it is off, only the main house's power (plugs) are off. The new house's power does come from the main house's DB on a different phase and the EL is 3kA (the main switch of the DB of the main house cuts all power on the property. Now, the new house's DB wiring has the EL connected to the geyser, stove and lights, which, as I understand isn't strictly necessary (but safer?). Had a electrician tell me that the EL was overloaded, but that doesn't explain the problem, since the EL ONLY trips with a ligthning strike in the area.

Do not feed the geyser, under floor heating, borehole pump, stove or any heavy current device from an EL.

These are safeoty devices that are designed to protect people so they are intended for plug points.

Industry doesn't use these since they are disruptive, tripping and causing unnecessary stoppages...

4 minutes ago, Richard Mackay said:

Do not feed the geyser, under floor heating, borehole pump, stove or any heavy current device from an EL.

These are safeoty devices that are designed to protect people so they are intended for plug points.

Industry doesn't use these since they are disruptive, tripping and causing unnecessary stoppages...

Agreed on the heavy current items... From DB's seen, normally heating items are pre-EL... Our borehole pump is only 370w and 750w on the booster pump, so hardly heavy current. The reason for the EL is it is fed off a sub which often had earthing problems. Once we had the right tolerance for our pumps on all breakers, it has worked perfectly since... I would personally rather have the protection and know if something goes belly up when working with water pumps. In our setup the EL trips when the pumps is having an issue (i.e. running hot).

Agreed! It's a great feeling to have all circuits fed from an EL. You know then all is well!

 

From reading all the comments I think there isn't the perfect solution. I would say move the earth from that particular area to another. increase the earth wire size or both with the earth rod/spike. A cheat would be getting a lesser sensitive earth linkage with a higher rating.
Here is an advantage or installing 2 spike or a larger spike = conductivity will be hire thus carrying more current than letting go. 
changing area = conductivity of an area may vary sometimes.
installing earth linkage before the main, on the earth which is just stretching electrical fundamentals will trip the earth and not the main power. in this case make sure your db has another source of earthing to help in a case where the linkage is disconnected.