[Question] Neutral Earth bonding of inverter

[JackC]

With reference to my "Inverter Battery Wiring" and other threads related to this topic.

I decided to go the route of a separate electrical circuit for the output of my inverter, as suggested against the above thread.

Which means that I will need to bond the Neutral and Earth on the inverter's output before feeding a new DB board. As suggested in one of the threads I will feed from the inverter output to a small box where I will bond the neutral and earth before feeding the new DB board. My inverter is a cheapie bought online (see attachment) but it is working fine. I get the following voltage readings on the inverter's output:
Between Live and Neutral - 219 Volt, between Live and Earth - 103 Volt and between Neutral and Earth 111 Volt. The earth is connected to the frame of the inverter with a 0.4 Ohm reading.

Question now; will it be safe to bond the inverter's Neutral and Earth just after the output plug (as explained above)? I tried to contact the distributor but without any success. Your advice/ opinion will be appreciated.

[Derlyn]

That's a VOV output. You cannot just bridge neutral to earth on that output.

[Thys LOW Elektries]

I would say the best point would be in the db before the earth leakage

[Thys LOW Elektries]

There are electrical ready boards available, prewired with plugs, some even have a bulkhead, but most of them don't have a main breaker though.
You can also buy all the parts and build a db according to your needs
Good luck with your project

[Derlyn]

Question.

Would it make life any easier for everyone if inverters were manufactured with built in earth leakage relays ?

[GCE]

Question.

Would it make life any easier for everyone if inverters were manufactured with built in earth leakage relays ?

No - Could be a problem with neutral earth bridges , if you running dedicated circuits especially in shops that have cctv alarms etc

Inverters are also generally made to an international standard and you can choose the different grid set ups according to the country you stay in

[Derlyn]

Another question ( sorry )

Never tried this before.

On a plug and play inverter where the output is not in any way connected to the the installation ...... if there's a leakage to earth on an appliance plugged in to the output, is there any earth leakage protection ?

[Isetech]

This is the reason the old SABS regulations worked, an inverter like this would never be SABS approved for use in SA to connect to an electrical installation. In this day and age anything goes, some of us try ot hold on to the old ways of doing things, in reality anything goes.

It would be an interesting to hear if an insurance company would pay out for a claim related to one of these units connected to an elctrical installation.

Just like the plug and play units, they are not designed to be connected to electrical installation period, but in Sa nobody realy car, desperate times call for desperate measures.

This neutral/earth bonding fiasco is a good expample of how bad things have got, with a 70 - 30 % in favour of the permemant bond, you can jump up and down till the cows come home, if the AIA says the regs dont apply and their decision rule and the DOl appointed them, who are we to argue ?

Now there is talk (the key word "Talk"... talk talk talk) of a 400 a page revision to the SANS book, which will include many new rules and regulations, if we cant even get the regs right from the present book hgow will new regulations help?

The best part is who is going to pay to bring all the hundreds, yes you heard right hundreds of thosands of solar installations already installed, up to standard.

One of the other interesting issues is going to eb the regisatration of all these units, yes that includes your small inverter connected to the electrical installation. I received a quote for an SSEG to be registered, it was over R10 000 and that doesnt include the council costs.

We are in for some interesting time ahead.

There is good news, a stage 10 load shedding schedule has been released, which means more and more work, the smart people who climbed on this band wagon are smiling all the way to the bank

[Justloadit]

Another question ( sorry )

Never tried this before.

On a plug and play inverter where the output is not in any way connected to the the installation ...... if there's a leakage to earth on an appliance plugged in to the output, is there any earth leakage protection ?

Interesting question, in the case that the unit is being fed through the inverter, and an earth fault occurs between Neutral and Earth, then the AC feed side ELU will trip, then the interesting part happens, the inverter will now switch on and supply the load with power. So effectively no earth fault trip.
Now the second scenario, if there is a Live to earth fault, then the AC feed side ELU will trip, the Inverter powers the load, and depending on the severity of the Live Earth fault, the inverter may or may not trip on an overload condition.

NOT SAFE!

So again here is the situation, if you provide the ELU safety on the output side of the inverter, then you are way more expensive than the next fellow who does not care, but sells and makes the sale because he is cheaper.

Go figure.
Cost trumps safety to most customers who have no understanding of electricity.

[Derlyn]

@Justloadit. Thank you my brother. That was my line of thinking.

Now to throw a spanner in the works with an inverter that has a vov output such as the one mentiioned above by JackC where an earth leakage on the output means diddly squat. 😂😂

[Dylboy]

For the VoV one when doing a DB tie or whatever, don't use the earth of the output and then bridge the Neautral and Earth on the "supply side" so basically not shorting the VoV.

So using the Line and Neutral only from the inverter and joing the out going supply Earth to the Neutral.

That is how I see it can be done on a VoV.

Sent from my CPH2197 using Tapatalk

[JackC]

Thanks everybody for your contributions. I will try to digest the information and try to come up with possible solutions.

I anyway decided not to bond neutral and earth on the output of the inverter, therefore I will keep my trolley as a portable solution. But I will try to make it as save as possible by introducing an ELU.

Once I am done with possible solutions, I will publish the diagrams on this forum for discussion.

One lesson that I however learned so far is to me thorough when buying online.

[Dave A]

That's a VOV output. You cannot just bridge neutral to earth on that output.

Not just a floating neutral?
Or did you check the specs on the unit?

[Derlyn]

Not just a floating neutral?
Or did you check the specs on the unit?

The specs on these types of inverters only give the live/neutral voltage output.

I was probably a bit hasty with my VOV reply. Its just seldom that one measures a floating neutral scenario so close to exactly half the supply voltage. ( possible, but seldom )
Of course the correct way, as with a generator as well, is to connect a load to the output before taking voltage measurements. I use incandescent light bulbs.
I was under the impression that the author had done this.

Had he not, it will be interesting to know the outcome after doing so.

[Isetech]

This is the way I understand the logic, right or wrong, I am sure someone will correct me.

Genrators, UPS, inverters and the like are designed for a specific application, which is why they are class 11 devices, not orginally designed to be connected to fixed electrical installation.

A class 11 devices doesnt have a floating neutral, it has 110 VAC on each leg, which reduces the voltage to make it a little safer for mobile use.

A floating neutral is a floating neutral in a 3 phase supply which creates an extremely dangerous situation, in the past neutral condustors have been stolen in sub station because the thief has learnt that they will not get electricuted if they cut it.

IF you are an electrician and been called out for a burning smell in a property, or burnt plug tops, ballasts and the like, you would have carried out tests and realised that the power had to be switched off asap, why because the voltage measured would in some cases be as high as 600-700 VAC