# Interest group forums > Electrical Contracting Industry Forum >  Inverter Install Compliance

## deejaypsy

I have a question for anyone out there with the knowledge to answer...
Myself and my business partner are both time served registered electricians and are doing a lot of inverter installs at the moment due to the load shedding issues we're experiencing.
Firstly, we are battling to find any decent supplier of inverters (pure sine preferable), so if anyone can point me in the direction of someone with a quality product i'd be interested to hear...
2ndly, the kind of install we are doing is a fully automated one.
Let me explain a bit...
The client supplies the UPS (for want of a better term...an inverter battery system is basically just that anyway...)
We install it as near to the mainboard as possible, and wire it into the mains with control and protective circuitry so that in the event of a power failure, only the critical circuits that the client requests will be powered off of the inverter/ups.
We wire the inverter so that when mains is on, the earth leakage supplies all of the plug circuits (and others that are run through it) as per normal.
When the mains fails and the inverter kicks in, it too runs through the earth leakage, supplying the critical circuitry, which is usually the tv and router plug circuits and the fridge, and possibly a lighting circuit or 2 (obviously the inverter setup is spec'd correctly for the amount of load required to be run).
The pure sine inverters are a dream, and run like this perfectly...however...the modified sine wave inverters do not run through the earth leakage.
They trip the earth leakage as soon as they come in, and you cannot reset the earth leakage on a modified wave.
So the only option is to wire the critical circuits off of the earth leakage.
Now how does this hold true according to the current regulations, where they state that all plug circuits should be protected by an earth leakage?
Do i need to tell the client that he must supply a pure sine wave inverter or his installation will not be compliant, or do the regs make allowance for this kind of install?
I realise that a UPS unit is designed to plug into a plug socket (thus excluding it from a CoC as it is not part of the fixed wiring), but if my client is asking me to automate his system so that he can have lights and usually 2 different (lounge and kitchen) plug circuits running off of his UPS in the event of a power failure, then how am i supposed to proceed?
Could someone tell me what the current regs have to say about an inverter as an alternative supply?
If a generator can be connected through your mainboard by means of an ATS, then surely so can a UPS/Inverter system.
Thanx

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## AndyD

> I have a question for anyone out there with the knowledge to answer...
> Myself and my business partner are both time served registered electricians and are doing a lot of inverter installs at the moment due to the load shedding issues we're experiencing.
> Firstly, we are battling to find any decent supplier of inverters (pure sine preferable), so if anyone can point me in the direction of someone with a quality product i'd be interested to hear...


Not sure about Plettenberg Bay but see if you can find a local Victron agent if you want a decent quality inverter.




> 2ndly, the kind of install we are doing is a fully automated one.
> Let me explain a bit...
> The client supplies the UPS (for want of a better term...an inverter battery system is basically just that anyway...)
> We install it as near to the mainboard as possible, and wire it into the mains with control and protective circuitry so that in the event of a power failure, only the critical circuits that the client requests will be powered off of the inverter/ups.


So the supply side of the inverter/UPS is hardwired onto it's own MCB in the DB? And the output side of the UPS is wired into the supply side of MCB's of the final circuits it's supplying? 
How big are these UPS's? (in KVA).
Are you marshalling all the UPS supplied final circuits into a clearly defined area of the DB or are you just removing the normal supply wiring of the selected circuit breakers and fitting new supply wiring that's coming from the UPS?




> We wire the inverter so that when mains is on, the earth leakage supplies all of the plug circuits (and others that are run through it) as per normal.
> When the mains fails and the inverter kicks in, it too runs through the earth leakage, supplying the critical circuitry, which is usually the tv and router plug circuits and the fridge, and possibly a lighting circuit or 2 (obviously the inverter setup is spec'd correctly for the amount of load required to be run).


I'm really confused how you're wiring this, can you make a sketch or drawing to show your layout and attach it?





> The pure sine inverters are a dream, and run like this perfectly...however...the modified sine wave inverters do not run through the earth leakage.
> They trip the earth leakage as soon as they come in, and you cannot reset the earth leakage on a modified wave.


I think you may have a wiring issue but if you can attach a drawing it will help enormously.





> So the only option is to wire the critical circuits off of the earth leakage.
> Now how does this hold true according to the current regulations, where they state that all plug circuits should be protected by an earth leakage?
> Do i need to tell the client that he must supply a pure sine wave inverter or his installation will not be compliant, or do the regs make allowance for this kind of install?


There are certain requirements that must be met but final dedicated circuits for IT equipment can be supplied without RCD protection. In your particular case I'm dead against this because I think you may have a wiring issue so removing the RCD will be treating the symptoms and not the cause which could leave potentially dangerous circuits. 




> I realise that a UPS unit is designed to plug into a plug socket (thus excluding it from a CoC as it is not part of the fixed wiring)


A common misconception, just because it 'plugs in' doesn't necessarily mean it's outside of the scope of the CoC. The system design you're describing will almost certainly require a CoC regardless of it being on a plug or being hardwired. 




> but if my client is asking me to automate his system so that he can have lights and usually 2 different (lounge and kitchen) plug circuits running off of his UPS in the event of a power failure, then how am i supposed to proceed?


 These sockets must be supplied with RCD protection.





> Could someone tell me what the current regs have to say about an inverter as an alternative supply?


 I'm not sure what you're asking. An inverter or UPS back-up supply is permitted as long as it's installed to be compliant. 





> If a generator can be connected through your mainboard by means of an ATS, then surely so can a UPS/Inverter system.
> Thanx


 I don't understand the question, a UPS has an internal seamless (usually 5-10mS) automatic transfer switch built into it.

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## bergie

i have also being doing a few of these installations lately and i install a small surface db next to the db. i move the 2 or 3 circuits into the new db with its own earth leakage relay.it is then supplied direct from the inverter. i have been thinking of installing a optional changeover switch,as the inverter supply might not be enough when eskom power is on. when eskom is off then obviously the customer will be careful what he plugs in.also if the inverter is faulty in future then there would be no power on those circuits until it is repaired or manually bypassed.
i would sign  a coc with a seperate db but not without, unless the original db has partitions in.

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jkamuz (02-Dec-15)

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## AndyD

We use both techniques depending on the layout of the existing DB and how easy it is to achieve separation. Many instances it's just easier and quicker to install a separate enclosure.

We rarely have overload issues because almost always the inverter is supplying a pretty static critical load and often the circuits are on dedicated sockets which reduces the likelyhood of something horrific being plugged in. I guess in a domestic application the risk of accidental overload would be far greater but we don't do the domestic side.

Did you manage a sketch deejaypsy?

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## deejaypsy

Sorry Andy,
Been a crazy end to a busy week. I've gotta rush out now again for a meeting...i'll post a sketch when i get back in a coupla hours...
 :Wink:

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## deejaypsy

> Sorry Andy,
> Been a crazy end to a busy week. I've gotta rush out now again for a meeting...i'll post a sketch when i get back in a coupla hours...




I hope you can make it out clearly enough?
All wiring is correctly sized and UPS circuits are marked in the board.
Your thoughts...

Seems to have come out quite small after uploading...try my dropbox link, maybe that'll be easier to see...
https://www.dropbox.com/s/kwt0z8safr...00332.JPG?dl=0

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## Tonye

> i have also being doing a few of these installations lately and i install a small surface db next to the db. i move the 2 or 3 circuits into the new db with its own earth leakage relay.it is then supplied direct from the inverter. i have been thinking of installing a optional changeover switch,as the inverter supply might not be enough when eskom power is on. when eskom is off then obviously the customer will be careful what he plugs in.also if the inverter is faulty in future then there would be no power on those circuits until it is repaired or manually bypassed.
> i would sign  a coc with a seperate db but not without, unless the original db has partitions in.


Hi Bergie. I have been checking what the regulations say & based on this have come up with a diagram. Could you possibly let me know if this would pass a coc.
http://www.power.edisplays.co.za/changeover.html

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## AndyD

> I hope you can make it out clearly enough?
> All wiring is correctly sized and UPS circuits are marked in the board.
> Your thoughts...
> 
> Seems to have come out quite small after uploading...try my dropbox link, maybe that'll be easier to see...
> https://www.dropbox.com/s/kwt0z8safr...00332.JPG?dl=0


Sorry Deejatpsy, I missed your reply until now.

I haven't been through your control circuit completely but it looks way overcomplicated, I'd go with separate RCD's for the essential and non-essential then redesign it much simpler. Even better if the essential circuits are only supplying lighting and computer equipment and other ClassII appliances then make the sockets red dedicated and do away with the RCD entirely on the essential ccts.

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## AndyD

> Hi Bergie. I have been checking what the regulations say & based on this have come up with a diagram. Could you possibly let me know if this would pass a coc.
> http://www.power.edisplays.co.za/changeover.html


Does your inverter not have an internal 10mSec switch?

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## Tonye

It does have an internal transfer switch which would allow an uninterrupted power supply to the mini DB. However this is for domestic use and need to allow larger loads on the mini DB when eskom mains are selected.
When used in inverter mode, the inverter circuit breaker is the primary overload protection.

I am using a 24 volt 2.4kva modified sign wave inverter with a .6 PF, together with 2 x 12v 105 amp hour deep cycle batteries. The inverter has a UPS & inverter setting ( different line low & line high detection).
It also has 2 charger settings 10A & 20A.

On mission critical equipment ie, Dstv decoder, Adsl router modem etc.. I have installed smaller UPS's,
To allow uninterrupted power while changing over.
However the modified sign wave inverter could not keep the UPS's running in online mode.
Little did I know that one requires a pure sign wave inverter to run a UPS in online mode.

I did eventually find a suitable UPS to operate on a modified sign wave. Problem solved.

I would just like to make sure that the diagram I submitted would pass a coc



I would also like to know if the diagram I submitted would pass a coc.

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## deejaypsy

> Hi Bergie. I have been checking what the regulations say & based on this have come up with a diagram. Could you possibly let me know if this would pass a coc.
> http://www.power.edisplays.co.za/changeover.html


Hi Tonye,
Just a question...
Why are you feeding your mini DB with a breaker that is on your main DB's EL, as the mini DB has its own EL anyway.

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## deejaypsy

> Sorry Deejatpsy, I missed your reply until now.
> 
> I haven't been through your control circuit completely but it looks way overcomplicated, I'd go with separate RCD's for the essential and non-essential then redesign it much simpler. Even better if the essential circuits are only supplying lighting and computer equipment and other ClassII appliances then make the sockets red dedicated and do away with the RCD entirely on the essential ccts.


Hi Andy,
I have since modified my design to include a 2nd EL solely for the use of the critical equipment and am in the process of redesigning the control circuit to simplify it as suggested.

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## bergie

hi tonye

your diagram looks good . i do it the same way. deejay is correct though the mini db supply breaker shouldnt be on the main dbs earth leakage relay.
i use a modular changeover switch and install it in the mini db.
as you mentioned , the customer can choose to leave it on inverter but be limited with total current or changeover to eskom and have full load.

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## Tonye

My bad. have changed diagram


One problem I had, was the inverter has a floating neutral on output side. Voltage tests between live & earth 110v, between neutral & earth 110v.
Earth leakage on Mini DB showed an earth fault and would not trip.
After consulting with an electrical engineer who stated the neutral needed a reference point, I connected the neutral to  main earth on the output side of the inverter.
Bingo, problem solved

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## deejaypsy

> My bad. have changed diagram
> 
> 
> One problem I had, was the inverter has a floating neutral on output side. Voltage tests between live & earth 110v, between neutral & earth 110v.
> Earth leakage on Mini DB showed an earth fault and would not trip.
> After consulting with an electrical engineer who stated the neutral needed a reference point, I connected the neutral to  main earth on the output side of the inverter.
> Bingo, problem solved


Ah hah!
This solves a problem i have been finding of an earth fault not tripping the EL.
So the solution is to earth the neutral on the load side(output) of the inverter?
This makes sense.
Thanx for the input.
The inverters i have installed are line interactive inverters so no changeover switch is required. It switches automatically on mains fail, but even when Eskom is available it runs in bypass mode, still supplying the critical load with power at the rated maximum size of the inverter...
 :Smile:

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## Tonye

Glad I could help.

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## Tonye

My inverters are also line interactive. The reason for running through the changeover switch is to allow the client to turn off
Equipment which may overload the inverter.

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## Tonye

> Ah hah!
> This solves a problem i have been finding of an earth fault not tripping the EL.
> So the solution is to earth the neutral on the load side(output) of the inverter?
> This makes sense.
> Thanx for the input.
> The inverters i have installed are line interactive inverters so no changeover switch is required. It switches automatically on mains fail, but even when Eskom is available it runs in bypass mode, still supplying the critical load with power at the rated maximum size of the inverter...


Just completed an installation. Pulling my hair out. Earth leakage keeps tripping when running on inverter
mode. Apparently their are different types of earth leakage units.
Type AC, sensitive to alternating current only
Type A, sensitive to alternating current and/or pulsating current with DC components.
Don't know if you have also experienced this.

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## DieterT

Nice job!

Like the trunking you used and the way it has the curve into the flush mounted DB, very neat.
I had no idea there was AC & A type earth leakages. Would the A type earth leakage have a difference with tripping on the inverter?

Normally we just implement a connection box at the output of the inverter/generator with a neutral bar inside and do a earth neutral connection and label it on the box.
This is also the point where we bring our earth spike into the installation, so kind off kills 2 birds with one stone + being able to safely earth the alternative supply.

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## Tonye

> Nice job!
> 
> Like the trunking you used and the way it has the curve into the flush mounted DB, very neat.
> I had no idea there was AC & A type earth leakages. Would the A type earth leakage have a difference with tripping on the inverter?
> 
> Normally we just implement a connection box at the output of the inverter/generator with a neutral bar inside and do a earth neutral connection and label it on the box.
> This is also the point where we bring our earth spike into the installation, so kind off kills 2 birds with one stone + being able to safely earth the alternative supply.


Hi Dieter,
Thanks for the compliment. The trunking is quite expensive but comes with all types of accesories,
making a neat job. I was also not aware of different types of earth leakage units.
Type AC should be fine on Pure sine wave inverters and Type A should work on Modified sine wave inverters. I will be doing further tests and let you know the outcome

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## Tonye

> Hi Dieter,
> Thanks for the compliment. The trunking is quite expensive but comes with all types of accesories,
> making a neat job. I was also not aware of different types of earth leakage units.
> Type AC should be fine on Pure sine wave inverters and Type A should work on Modified sine wave inverters. I will be doing further tests and let you know the outcome


It wasn't neccesary to use a Type A Earth leakage unit. Found that the type Ac I was using was faulty.
Installed a new one and problem solved.

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## DieterT

> It wasn't neccesary to use a Type A Earth leakage unit. Found that the type Ac I was using was faulty.
> Installed a new one and problem solved.


Great news on being able to use a standard earth leakage and not having to spend extra money.
And very upsetting no know that earth leakage where faulty especially because it being an earth leakage...much concern for the products our country is bringing in.
Which make was it?

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## Tonye

> Great news on being able to use a standard earth leakage and not having to spend extra money.
> And very upsetting no know that earth leakage where faulty especially because it being an earth leakage...much concern for the products our country is bringing in.
> Which make was it?


ACDC, replaced with ABB

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## DieterT

> ACDC, replaced with ABB


ACDC  :Nono:  I had my fair share of ACDC products. Had a chat with one of their reps on a issue with a voltage regulator, his words where when I mentioned that the regulator is not SABS approved was that I would be amazed how many products they sell ain't SABS approved and since I realized that saving a buck on something that might cost someone their life ain't worth it. Luckily they are forcing suppliers now to take responsibility for their products as well which has been mostly left on the installer and user/lessor.
Imagine installing a earth leakage that fails on a situation where someone gets shocked... or a wire connection shorts out and causes a fire but the circuit breaker never trips.
I'd rather stay with the safehouse products and products that has a good name in the industry.

I heard that CHINT is making a comeback as it has been taken away from RIKEN who used to sell them (and eventually started selling a look a like)
Other than than I like LS , ABB , CBI ( I am concerned about) , ONESTO ( also in question ) , LEAR ( also somewhat cautious about that one) I might have left out one or 2 that also got good industry standing.

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## SilverNodashi

> ACDC  I had my fair share of ACDC products. Had a chat with one of their reps on a issue with a voltage regulator, his words where when I mentioned that the regulator is not SABS approved was that I would be amazed how many products they sell ain't SABS approved and since I realized that saving a buck on something that might cost someone their life ain't worth it. Luckily they are forcing suppliers now to take responsibility for their products as well which has been mostly left on the installer and user/lessor.
> Imagine installing a earth leakage that fails on a situation where someone gets shocked... or a wire connection shorts out and causes a fire but the circuit breaker never trips.
> I'd rather stay with the safehouse products and products that has a good name in the industry.
> 
> I heard that CHINT is making a comeback as it has been taken away from RIKEN who used to sell them (and eventually started selling a look a like)
> Other than than I like LS , ABB , CBI ( I am concerned about) , ONESTO ( also in question ) , LEAR ( also somewhat cautious about that one) I might have left out one or 2 that also got good industry standing.


As matter of interested, what are your concerns with  CBI, ONESTO and LEAR?

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## DieterT

> As matter of interested, what are your concerns with  CBI, ONESTO and LEAR?


CBI concerns me as they where the industry standard, basically had a monopoly on the South African industry.
They became over priced as they knew most people where forced to use them because they had samite back rail type boards.
Later on I started noticing faulty breakers. One time an earth leakage and circuit breakers on two other occasions.
Now also they don't even have the SABS mark on their breakers, where they used to be the fore runner of the SABS mark...
And yes CBI has an representative at the SABS board.

With ONESTO I have had quite a few faulty's. Never did much research of who they are and where they come from. They where at the time I used them over priced compared with CHINT as CHINT used to be the dinrail industry standard.

With LEAR the only concern I carry is the certifications. I have not had one faulty up to this date and they make a good replacement for CBI also being samite mount.
After a good conversation with one of the guys in charge at LEAR (think his name was Louis) it was well understood that certification is done by batch and not per unit as this would cause each breaker to be increased in price by at least R5. He did also show that they carry the certification in order to sell their products in South Africa (not that I have much confidence in what South Africa allows and not allow). Apart from their certifications, at least they form part of Safe House and they are good competition to CBI which gives us installers an alternative and the client affordability.

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## SilverNodashi

> CBI concerns me as they where the industry standard, basically had a monopoly on the South African industry.
> They became over priced as they knew most people where forced to use them because they had samite back rail type boards.
> Later on I started noticing faulty breakers. One time an earth leakage and circuit breakers on two other occasions.
> Now also they don't even have the SABS mark on their breakers, where they used to be the fore runner of the SABS mark...
> And yes CBI has an representative at the SABS board.
> 
> With ONESTO I have had quite a few faulty's. Never did much research of who they are and where they come from. They where at the time I used them over priced compared with CHINT as CHINT used to be the dinrail industry standard.
> 
> With LEAR the only concern I carry is the certifications. I have not had one faulty up to this date and they make a good replacement for CBI also being samite mount.
> After a good conversation with one of the guys in charge at LEAR (think his name was Louis) it was well understood that certification is done by batch and not per unit as this would cause each breaker to be increased in price by at least R5. He did also show that they carry the certification in order to sell their products in South Africa (not that I have much confidence in what South Africa allows and not allow). Apart from their certifications, at least they form part of Safe House and they are good competition to CBI which gives us installers an alternative and the client affordability.


Thanx for the info. I generally prefer CBI and haven't had problems with them yet.

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## AndyD

I've stopped using the CBI electronic QAT timers, we've had a lot of failures over the last 12 months.

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## deejaypsy

> I've stopped using the CBI electronic QAT timers, we've had a lot of failures over the last 12 months.


I dont know why they ever changed them! The old type with the push buttons were solid. The new touch screen are not my cup of tea  :Frown:

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## hartdev@hotmail.com

I have had issues with Onesto breakers now on a few occasions. In one case a 7kw Instantaneous Water heater was running on a 20amp Onesto circuit breaker and there was no tripping.
I think we all know how dangerous that was.
I have been using Schneider circuit breakers almost exclusively for 2 years now and not had one failure, 2 years is not very long but so far i'm impressed.
I found this thread very interesting and informative.
 I have almost completed the electrical installation in a nice new home in Cape Town. The company which installed the solar and battery backup inverter etc were very quick, in and out on a day I was not on site. They have requested that i rewire the D.B to isolate backup circuits from the non backup circuits. By doing this i would have to disconnect the backup circuits from the earth leakage device. The solar installers don't seem to have an earth leakage device at all in their though so I am trying to find out if the backup inverter has some sort of built in earth leakage protection, I downloaded a manual and saw nothing mentioned. (Victron 24/3000/70). 
Does anyone know if we require a specific type of energy dispenser to allow our client to feed back into the grid? This is something I was told the solar installers would see to but no change has been made to the standard ED installed by ourselves.
The solar has not yet been switched on to feed back into the grid, i am worried it could cause some sort of damage.

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## Tonye

> I have almost completed the electrical installation in a nice new home in Cape Town. The company which installed the solar and battery backup inverter etc were very quick, in and out on a day I was not on site. They have requested that i rewire the D.B to isolate backup circuits from the non backup circuits. By doing this i would have to disconnect the backup circuits from the earth leakage device. The solar installers don't seem to have an earth leakage device at all in their though so I am trying to find out if the backup inverter has some sort of built in earth leakage protection, I downloaded a manual and saw nothing mentioned. (Victron 24/3000/70).


I will try and answer your questions to the best of my ability & also with reference to SANS 10142 regulations.

If alternate power is to be fed into a DB board together with Grid power, you need to have a split neutral bar. One for Grid power & one for the alternate power.
Both power sources earth terminals need to be earthed to the main earth terminal.
You also need to have a seperate main switch to disconnect the alternate power to the main DB.
Also a power on indicator (visible or audible) shall be provided together with a notice indicating that the alternate power main switch shall also be switched off in an emergency.

With regards to the earth leakage, to my knowledge no inverters have built in earth leakage protection. This is because inverters have a floating neutral with no reference to earth. By measuiring voltage on the inverter output, one usually finds Live-Neutral = 220v, Live- Earth = 110v & neutral- Earth = 110v.
To resolve this problem & ensure correct operation of an earth leakage unit, you need to bridge the neutral to earth on the inverter output.
Some inverters have an auto neutral to earth connection when the inverter is running in inverter mode.
Bear in mind, if the inverter does not have an auto neutral to earth connection and you bridge the neutral to earth on the inverter, the supply to the inverter charger (if it has a built in charger) cannot be fed from a circuit breaker connected to the grid fed earth leakage unit.
The earth leakage would trip, as it sees the bridged neutral to earth as a fault.

The regulations also state that if alternate power feeds plug circuits, they have to have earth leakage protection.

If not all plugs are being fed from the alternate power source, you would have two earth leakage units. One for grid fed plugs & one for alternate power fed plugs.

I have just completed an inverter installation on a three phase board feeding single phase loads with split neutrals. The same would apply on a single phase supply.

I have attached a basic wiring diagram showing essential wiring

wiring diagram new.pdf

Hope this helps

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AndyD (05-Dec-15), hartdev@hotmail.com (02-Jan-16)

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## AndyD

> To resolve this problem & ensure correct operation of an earth leakage unit, you need to bridge the neutral to earth on the inverter output.
> Some inverters have an auto neutral to earth connection when the inverter is running in inverter mode.
> Bear in mind, if the inverter does not have an auto neutral to earth connection and you bridge the neutral to earth on the inverter, the supply to the inverter charger (if it has a built in charger) cannot be fed from a circuit breaker connected to the grid fed earth leakage unit.
> The earth leakage would trip, as it sees the bridged neutral to earth as a fault.


I think it's against the regs to have a neutral-earth connection within the installation itself, there's implications for fault current alternative paths etc. I'd need to comb the regs when I've got time in the office to find the relevant paragraph.

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hartdev@hotmail.com (02-Jan-16)

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## DieterT

@Tonye
Just to add

In regards to plug circuits being under earth leakage. All plug circuits shall have earth leakage protection wheter or not from mains or alternative supply. 

It's only dedicated circuits which can be taken off earth leakage protection.

*take note of conditions to be adhered*

Cutting a normal plug top off and putting on a dedicated plug top so to fit the half earth plug socket does not make the appliance acceptable for use on non-earth leakage protected plug sockets

Also, where visual (light indication)/audible indication is required for alternative supply is where the alternative supply has automatic change over. Where manual change over is used, notice of alternative supply is sufficient. Also rember that all DB boards fed from alternative supply should have this indication, including sub DB boards.

@Andy
You are very much correct in saying that. The earth neutral bridge is only allowed on the supplier side (thus a little box between the alternative supply and DB board with earth neutral bridge plus indication of such is sufficient)

Can't remember the page in SANS10142, but it basically says that the earth neutral bridge is not allowed to be made on the consumer side, thus on the DB board.

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hartdev@hotmail.com (02-Jan-16)

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## Tonye

@Andy, I agree. Regulation 6.1.6 stipulates " The neutral conductor shall not be connected direct to earth or to the earth continuity conductor on the load side of the point of control.
However the neutrals of each supply shall be earthed at the supply (Regulation 7.12.3.1.3) and then Regulation 7.12.3.1.4
covers the split neutral scenario.

@Dieter, I agree with no earth leakage required for dedicated circuits.
I was referring to std plug circuits.

With regards the audible or visual indication for alternate supply, the regulations do not differentiate between manual or automatic switching.
Regulation 7.12.2.1a simply specifies that if part of a DB is fed from an alternate supply, then such indication is required together with a notice.

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hartdev@hotmail.com (02-Jan-16)

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## DieterT

> With regards the audible or visual indication for alternate supply, the regulations do not differentiate between manual or automatic switching.
> Regulation 7.12.2.1a simply specifies that if part of a DB is fed from an alternate supply, then such indication is required together with a notice.


Thnx for pointing that out. I was referencing from municipality's requirements documentation, but in effect the SANS10142 over rules any of their requirements.

I see "The wiring of premises: Part 3: Low Voltage Embedded Generators" target date is 2016-03-31. This is going to be very interesting....

https://www.sabs.co.za/Business_Unit...Work/PW067.PDF

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hartdev@hotmail.com (02-Jan-16)

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## Dave A

> I think it's against the regs to have a neutral-earth connection within the installation itself, there's implications for fault current alternative paths etc.


Bear in mind any given portion of the installation is only going to be powered by one supply at a time. The trick is to configure everything in such away that the neutral-earth connections are only on the (various) supply sides. (i.e. on the supply side of the crossover switch).

That said - 
This is normally easily achieved where the alternative supply is a generator (excluding V-0-V generators with a centre tap to earth). The situation where the alternative supply is an inverter and the crossover switch is essentially incorporated in the inverter supply device does look like it might pose some special challenges.

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hartdev@hotmail.com (02-Jan-16)

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## Tonye

@Dave, hence the split neutrals

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hartdev@hotmail.com (02-Jan-16)

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## hartdev@hotmail.com

Thanks so much for the information guys, this really is not something you can ask most electricians working around the neighbourhood.
I have not yet looked at your diagram Tonye but I will as soon as I can get on my PC.
The solar installer has apparently applied for the grid feed energy dispenser so that is being taken care of.
He has gone quiet since I mentioned an earth leakage device  :Smile:  I'm betting he has plenty of installations in Cape Town with no such protection.
I will have to sort that out. I plan to power his inverter charger from a non earth leakage protected circuit. From his inverter output I will have to connect the neutral to earth before his mains/off/inverter change over switch, I will then wire this through an earth leakage device into our main D.B where the dedicated circuits will have their own neutral bar. I will add an indicator light to be on whenever the dedicated circuits are on with a notice indicating that the solar installers change over switch needs to be in the off position to completely isolate the installation.
Although I don't like connecting the earth to the neutral on the output side of the inverter, I feel it is safer than doing without an earth leakage device.
As long as there is no connections between earth's or neutrals of the dedicated circuits and the standard circuits there shouldn't be any problems.
It's a constant argument I have with an electrician friend I have that each circuit is to have it's own earth wire and its own neutral wire etc, this is one of those times when it becomes so important. Some guys like to connect every earth together in the house, although it ensures a good earth when there is a problem with a circuit it can complicate everything.
Thanks again guys, I will try to find the specific paragraphs in the sans book so I can motivate to the project manager why these changes need to be made. I won't sign off if it is not done...

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## Tonye

@hartdev, I do not think the changeover switch would be considered a main switch to disconnect the alternate power.
As the changeover switch changes from grid power to zero power & then Inverter power, it would be possible that power can still be
fed to the essential loads if the changeover switch is not in the correct position.
It would probably be safer to install a d/pole circuit breaker with low threshold value.(check Regulation 7.12.4) This way you will also be protecting the Inverter & cabling.
Also ensure that the power supplying the inverter charger is fed from the input side of changeover switch (grid input) & not the output side feeding the essential loads, or your inverter will go into a frenzy when running on inverter battery mode.
Also, although the neutrals must be split, the Earths should all be connected to the main Earth.
Check with your Solar inverter guys if the inverter has a auto neutral to earth connection on inverter mode.
If so, you would not need to manually bridge the neutral to earth.
Once installation is complete & while running in inverter battery mode, simply test the earth leakage unit feeding the essential loads. If the circuits are healthy & tripping the earth leakage, you are sorted.

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hartdev@hotmail.com (02-Jan-16)

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## hartdev@hotmail.com

Thanks very much guys
Sorry for the delayed reply. The solar installer has been really slack in answering any questions, eg. whether there is an auto neutral to earth connection etc.
In emails where the client and project manager were CCd , he kept writing things like " I will try my best to make the changes to conform to Devereux's standards" (Devereux being my first name).
I made it quite clear that they were in fact sabs standards and not my own.
I disconnected his system and issued my COC for the home installation without his system included and informed him that he would need to hire a registered electrician to sign off his installation with a supplementary certificate to mine .I will be returning in a week or two to make sure it has been done safely and the neccessary indicators,signage and earth leakage protection installed, but if not, I won't simply wash my hands of it. Safety is number 1 and I will ensure it is done properly.
Thanks so much for your input on this matter, wishing you all a very happy new year.  :Smile:

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jkamuz (02-Jan-16)

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## Pieter00

What about a 2 pole circuit breaker on the inverter input and output side? And cable size on the AC side due to the charge current that the controller is set at?

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## JustJohann

I also recently had a client ask me to install a inverter that chargers batteries from both mains and solar (not doing the solar now but wanted the option there) I checked the rating plate and see that the max current for the inverter is 30 amps. Having space in the cupboard where his 2 existing dbs are already installed I went ahead and installed a 32amp double pole breaker (so it acts as both a overcurrent protection and isolator) I then fed a short run of 4mm twin and earth to the inverter. Then from the inverter I took another 4mm twin and earth feeding to a small db with a 25 amp double pole breaker feeding a earth leakage which in turns feeds a 20amp breaker. From this 20amp breaker i installed a new plug circuit in his house with red dedicated plugs at his 2 tvs his dstv decoders,alarm,cctv and his wifi router. I know the red dedicated plugs is a bit of an overkill but he wanted an easy way to identify which plugs is on the inverter so that nothing unnecessary gets plugged into them and that was the easiest solution. I still need to go apply labels and seeing as everyone is talking of a indicator light I will probably have to look at installing some kind of led light to show that its live.

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