Earth leakage trips everytime loadshedding ends

[rodga]

Hi All

With my limited electrical knowledge Ive been trying to figure out what could be causing this issue. Every time load shedding period ends and the power is restored, the earth leakage trips. This is fine when someone is at home and its the middle of the day, so it can just be switched on again. But its a real pain when we are not home or we have LS during the middle of the night, I usually wake up to switch everything on again so the fridge and bedroom fans can go back on.

I have had 2 "electricians" out here in the last few months. The first said that the earth leakage circuit breaker is faulty and its needs to be replaced. So we did that and it changed nothing. Then he said the whole house needs to be rewired. All the while not providing any actual reasons/causes for this issue. The second guy at least had an earth leakage tester but did not pick up anything out of the ordinary. He recommended moving the geyser, stove and outside lights of the earth leakage. I was at first unsure, but after reading some discussions it seems that these devices are not required to go via a ELCB. But I said I will call him when Im ready.

So to avoid spending any more money on something that may or may not work, or just moving things off the ELCB and therefore basically ignoring the issue, I want to get an electrician that has the correct equipment and knowledge to properly diagnose the issue before going ahead with a solution. Please help me find this person, Im based in Centurion so anyone in the area would be first prize.

[Dylboy]

Hi there Rodga

To me it seems the house as a lot of "natural " earth leakage. So when power comes on and everything starts then the leakage is all at the same time.

New regs cant take geysers of ELU (earth leakage device). But I recommend getting a second ELU and split the board so the adding of the natural earth leakage is limited and split between each ELU.

If that does not work I would get the circuits insulated resistance tested to see if there is any breakdown.

I am away the next 2 weeks but hopefully someone closer can take a look.

Once back and not sorted will see of the boss is happy to take a trip with me to you to try see what we can do.

Also maybe someone wiser than me may have a better idea of what could be happening




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[rodga]

Hi there Rodga

To me it seems the house as a lot of "natural " earth leakage. So when power comes on and everything starts then the leakage is all at the same time.

New regs cant take geysers of ELU (earth leakage device). But I recommend getting a second ELU and split the board so the adding of the natural earth leakage is limited and split between each ELU.

If that does not work I would get the circuits insulated resistance tested to see if there is any breakdown.

I am away the next 2 weeks but hopefully someone closer can take a look.

Once back and not sorted will see of the boss is happy to take a trip with me to you to try see what we can do.

Also maybe someone wiser than me may have a better idea of what could be happening




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Thanks for the advice, I had that same thought of the leakage overwhelming the breaker when everything comes back on. Im sure I can reuse the old ELCB that was removed a few months ago too.
Will definitely get in touch if I dont find someone before then.

[ians]

CBI earth leakage?

I am hearing a lot of complaints about tripping earth leakage and alarms going off.

I am convinced that both my hard drives are destroyed thanks to load shedding.

You need a leakage current clamp ... I wish you luck trying to find a sparkie who carries one (@R4-6k for one) ... very few of us carry them.

[GCE]

We have been finding that the surge arrestor type plug tops that are there to protect equipment are also causing problems when power comes back on after load shedding .
The surge arrestor will take the spikes down to earth and the earth leakage sees it as a fault , which is correct , and it is doing it's job and so is the surge arrestor.

Bit of a catch 22 situation

A lot of the new fridges etc have mosfet's which are also doing it

Best would be to install an extra ELU and put fridge etc on a dedicated circuit.

Best way to test is unplug the fridge on the next load shed , maybe TV as well , computers , routers ,also any surge arrestor type plug tops and see if the problem disappears .

Would be interested to hear the feed back.

We have all the testers in the world , including a leakage current clamp , and have struggled on some of the intermittent faults of late.
I had a query on Friday , with a 200Kva genset . On load shed to generator , everything fine , from genset back to mains the main CB trips instantly. Reset immediately and all is fine. I suggested disconnecting the surge arrestors as a test and have not heard back. Installation has not changed in the past 2 years , maybe the surge arrestors where getting tired or the inrush current settings on the CB had been adjusted or got tired.
There are lot's of funny's happening at the moment and I have picked up that the frequency is jumping every 2 hours on sites that I can access and monitor. The sites are 300Km apart , so it is an Eskom thing.

[ians]

I have a customer with those red plug tops on just about every extension plug ... no tripping issues.

I rewired the building 3 weeks ago and fitted 2 earth leakage units per DB ... no CBI earth earth earth leakages were used on the site.

the callouts I attended to recently ... all had CBI earth earth leakage units.

[Justloadit]

On load shed to generator , everything fine , from genset back to mains the main CB trips instantly. Reset immediately and all is fine.

I am assuming that the genset is a diesel based one, and not the cheap 5kW V-0-V generators I suspect that there is a floating earth when connected to the genset, so when switching back to mains, the circuit is "charged" due to the floating period of time, and when connecting back to mains the "charge" is then discharged to earth tripping the ELU.
Check that the generator Neutral is connected to earth with an earth resistor.

[Dylboy]

Very good point on the surge arrestors. That is why now they want us to use a spark gap SPD for the Neutral. As the MOV can after time break down and leak to earth.
Also they kinda say to install the MOV spd afyer ELU for that reason.

Kicking my self for not thinking of that as done a fair bit of CPD stuff on it and slowly getting to grips... and having a whole lot more questions everytime I learn something hahaha.

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[Derlyn]

I think most of us have been called out for similar problems earth leakage tripping at the resumption of power after loadshedding.

Here are my experiences.

1. Old Heineman 20mA earth leakage relays. Replaced earth leakage relay, problem solved.

2. Create your own load shedding with the main switch. If earth leakage trips then repeat process with a circuit isolated.

If fault persists then repeat with more circuits isolated until earth leakage does not trip when mains are turned on.

3. Install 2nd earth leakage and put all the circuits that were isolated, throufh it.

4. Do final testing.

The above method has solved the problem everytime for me.

We must remember that there are sometimes huge surges when power is switched on after loadshedding which aggrevate the situation.

The neatest solution I have personally seen to avoid any power surges after loadshedding is to take the mains through a contactor that is energised by a delay on timer so that your power only comes on a minute or two after everyone else's. By the time your power comes on then all those nasty surges have already done their thing to everyone else.

Sorry for the long essay

Peace out .. Derek

[ians]

If you are going to go to that expense ... I would strongly advise you instal a trip connect unit ... it will prevent the contactor reenergising and a time can be set on the unit ... if the neutral is missing resulting in higher than normal voltage (600+ VAC)

From years of experience with load shedding ... it will stop in a couple weeks ... everyone forgets about it ... then suddenly it is at the top of everyone's list again ... generator sales go through the roof ... battery inverter prices go crazy and so the cycle just goes round and round.

A little forward panning will not only save a ton of cash ... but also prevent issue with your electronics ... which might not fail today or tomorrow ... but will fail sooner or later.