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Earth Leakage - Nuisance Tripping On Power Restore


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Hi all, 

Not sure where to start with this, I have 3 phases with a common neutral between all 3 phases (only actually running 2 phases at the moment). There is a sub DB in my garage which I installed about 6 months ago by pulling up the mains into the house and splitting it between the sub-DB (input) and returning to the house's mains. This will be where I install my solar in the coming months. There is a generator connected here as well with a change-over switch but this is not run much and doesn't form part of the tripping (except when changing the change over from backup back to mains)...

I replaced a dodgy earth leakage that would not trip around 6 months ago with a Gewiss 3 phase earth leakage CBI was unavailable at the time.  Everything was fine up until about 2 months ago. 

I now get random EL trips when load shedding returns and when randomly restoring power. I can replicate this 1 in every 5 or 10 times by turning off the mains breaker and reapplying, generally, the EL will go straight back up, on the odd occasion it trips 2-3 times before finally settling. The tripping never happens without a loss of mains first. 

I have been circuit by circuit to try and figure this out, but I cannot get to the bottom of it - I am happy to pay a professional to investigate it, but I don't want them to come and spend the time doing what I have already done. I am happy to replace the EL as well. I was thinking to rather put in 3 separate single-phase breakers instead to assist in isolating the issue further. 

Any advise on where I can look?  

Edited by spotity
typo
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  • spotity changed the title to Earth Leakage - Nuisance Tripping On Power Restore

You must feed the inverter through a 2 pole or 4 pole circuit breaker from municipal supply and bypass the  EL in the main DB and put a circuit breaker and EL after the inverter and make sure all neutrals are seperated on 2 seperate bars in the DBs

I hope all the other sparkies on this forum will check this.

 

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49 minutes ago, Clint said:

You must feed the inverter through a 2 pole or 4 pole circuit breaker from municipal supply and bypass the  EL in the main DB and put a circuit breaker and EL after the inverter and make sure all neutrals are seperated on 2 seperate bars in the DBs

I hope all the other sparkies on this forum will check this.

 

I take note and agree, but as you are use the wording 'must',  I would like to add that I reserve the right  to connect the inverters grid feed after the MAINS ELD. I regard it important for my own installation in order to detect earth leakages on the PV feed to the inverter. 

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58 minutes ago, Clint said:

You must feed the inverter through a 2 pole or 4 pole circuit breaker from municipal supply and bypass the  EL in the main DB and put a circuit breaker and EL after the inverter and make sure all neutrals are seperated on 2 seperate bars in the DBs

I hope all the other sparkies on this forum will check this.

 

Thanks for the response Clint, at the moment I don't have an inverter installed, this is the plan in the next coming weeks. 

Currently the mains is split to the garage DB where it goes into a dual pole mains switch, feeds into a change over and then back to the house via the 4x16mm cable. The sub DB currently has no ELD

Edited by spotity
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Check that earth and neutral is bonded on the municipal side of the meter. Disconnect your incoming neutral and test that all outgoing neutrals aren't earthed. Throw away all fluorescent lights. Check all units with caps on them that live and neutral weren't changed around leading to caps charging... install three seperate earth leakages.

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6 minutes ago, frivan said:

Check that earth and neutral is bonded on the municipal side of the meter. Disconnect your incoming neutral and test that all outgoing neutrals aren't earthed. Throw away all fluorescent lights. Check all units with caps on them that live and neutral weren't changed around leading to caps charging... install three seperate earth leakages.

Agree

The Capacitor theory is very interesting.Those damn old flourescent lights are just a fire hazard,replce them with LED lights ASAP

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9 minutes ago, Clint said:

Agree

The Capacitor theory is very interesting.Those damn old flourescent lights are just a fire hazard,replce them with LED lights ASAP

I installed an electronic ballast once for 12V LED lights. The first time I switched it on, it tripped my earth leakage but never since... so even LEDs can cause problems.

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21 minutes ago, frivan said:

Check that earth and neutral is bonded on the municipal side of the meter. Disconnect your incoming neutral and test that all outgoing neutrals aren't earthed. Throw away all fluorescent lights. Check all units with caps on them that live and neutral weren't changed around leading to caps charging... install three seperate earth leakages.

No fluorescent lights, only retrofit LED tubes in the garages, rest of the house is LED 220V downlights

Will check Earth and Neutral are bonded on the municipal side and double check all outgoing neutrals aren't earthed. 

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