Neutral earth bonding on backup systems.

[GCE]

Morning

I see Nersa have published the latest update for NRS-097-2-1 Ed3 which amplifies the ECA stance on Neutral Earth Bonding

Extract pasted below and full document attached

5.4 Neutral to earth bonding when forming an intentional island
5.4.1 To prevent a SSEG neutral connection to the the utility neutral through an earth conductor when the SDU opens, the SSEG shall not have a permanent neutral bonding to earth.
5.4.2 A hybrid system intended to form an intentional island on the load side during utility supply interruption shall open the SDU to prevent unintentional island on the utility side.
5.4.3 Since the SDU opens the neutral on the utility side, the intentional island neutral shall be bonded to earth within 200 ms after the SDU operation using a neutral to earth bonding unit (NEB).
5.4.4 The NEB shall open within a time period of 200 ms before the SDU reconnects the inverter to the utility supply.
5.4.5 The NEB shall consist of an electromechanical switching device rated at the nominal current rating of the inverter
5.4.6 The total clearance between the inverter neutral and earth conductors when the NEB is switched off, shall be equal the clearance of the SDU in its open state or more.
5.4.7 The NEB shall be an internal inverter component or an external device that is activated by a dedicated control port of the inverter.
5.4.8 The inverter data sheets shall indicate that it contains an internal NEB or a dedicated NEB control port for external devices.
5.4.9 Installation requirement: Inverters equipped with the NEB control port only, shall have external electromechanical NEBs installed that are SANS/IEC 60947-1 and SANS/IEC 60947-4-1 certified

[ACElectric]

It is quite clear now that most such inverters, as it is in the box, INCLUDING a Sunsynk - needing EXTERNAL (or internal) MODIFICATIONS, does NOT COMPLY WITH REGULATIONS and SPECIFICATIONS and as such are not allowed to be connected and/or installed in an electrical installation as required by the regulations.

If i have to "modify" a 20A cbi breaker to trip at 20A whether you do the modification inside the breaker or outside, -that breaker NO LONGER COMPLIES with regulation. Same with V-O-V gennies, you cannot change the the internal wiring to "make them compliant" They would have to be re-certified 1st.

It could then be quite possible, and easy, to successfully proof in a court of law that most coc's issued in such inverter installations, where such modifications are effected to modify the electrical apparatus, is in fact, invalid, because such modification would render the electrical apparatus classification/certification and approval invalid.

[GCE]

It is quite clear now that most such inverters, as it is in the box, INCLUDING a Sunsynk - needing EXTERNAL (or internal) MODIFICATIONS, does NOT COMPLY WITH REGULATIONS and SPECIFICATIONS and as such are not allowed to be connected and/or installed in an electrical installation as required by the regulations.

If i have to "modify" a 20A cbi breaker to trip at 20A whether you do the modification inside the breaker or outside, -that breaker NO LONGER COMPLIES with regulation. Same with V-O-V gennies, you cannot change the the internal wiring to "make them compliant" They would have to be re-certified 1st.

It could then be quite possible, and easy, to successfully proof in a court of law that most coc's issued in such inverter installations, where such modifications are effected to modify the electrical apparatus, is in fact, invalid, because such modification would render the electrical apparatus classification/certification and approval invalid.

I disagree with you - There is an option to select an output to activate a bonding "relay " if required. The same way that adding a Lan card or wifi module would be acceptable.

If I buy a 250Amp C/Breaker and need a Normal open contact , I buy the contact block and ,on some CB, have to open the CB to install the block or a shunt coil is a similar exercise - Do I need to send that back to certify ?

I buy a car and 3 months later decide that I want to fit a towbar , or mag wheels - Do I need to take it back for road worthy/recertification ?

With regards to a court of law and COC I would point you in the direction of SANS10142-1 Clause 5.1 - The method to create an earth neutral bond is clearly described as an option on the equipment and you would use a suitable sized relay/contactor suited for the installation and fault levels which comes with it's own certification.


5 Fundamental requirements
5.1 General
All commodities in an electrical installation shall be installed in accordance
with the requirements in this part of SANS 10142 and with the manufacturer's
instructions, where applicable.
NOTE 1 This clause contains the general safety principles applicable to electrical
installations.
NOTE 2 The manufacturer's instructions may contain more stringent requirements.

[ACElectric]

I disagree with you - There is an option to select an output to activate a bonding "relay " if required. The same way that adding a Lan card or wifi module would be acceptable.

If I buy a 250Amp C/Breaker and need a Normal open contact , I buy the contact block and ,on some CB, have to open the CB to install the block or a shunt coil is a similar exercise - Do I need to send that back to certify ?

I buy a car and 3 months later decide that I want to fit a towbar , or mag wheels - Do I need to take it back for road worthy/recertification ?

With regards to a court of law and COC I would point you in the direction of SANS10142-1 Clause 5.1 - The method to create an earth neutral bond is clearly described as an option on the equipment and you would use a suitable sized relay/contactor suited for the installation and fault levels which comes with it's own certification.


5 Fundamental requirements
5.1 General
All commodities in an electrical installation shall be installed in accordance
with the requirements in this part of SANS 10142 and with the manufacturer's
instructions, where applicable.
NOTE 1 This clause contains the general safety principles applicable to electrical
installations.
NOTE 2 The manufacturer's instructions may contain more stringent requirements.

Thank you, i will have to agree to disagree - this sudden burst of push-through regs (regarding this bonding issue) all of a sudden, and the dubious article published here (https://ecasa.co.za/technical/neutra...ing-clarified/) smells like an elastoplast plaster trying to fix the real issues, equipment not complying with SABS regs and standards.

It is actually a requirement that it should comply as a piece of equipment. - it does not. Part of the job of the inverter is to comply with the bonding regs - it does not.

Using your 250A CB argument, I then can sell a 250A breaker but, i 1st require you to install another device in series that makes sure it trips at 250A, my breaker simply does not meet the 250A standard. The car and towbar analogy i fail to understand as there are a complete different set of regs and the electrical regs does not apply.

It seems, as is the norm in this country, that double standards exist everywhere.

[Justloadit]

It is actually a requirement that it should comply as a piece of equipment. - it does not. Part of the job of the inverter is to comply with the bonding regs - it does not.

[ATTACH=CONFIG]8891[/ATTACH]

Can you provide the reference to this statement in the regs please.

[Dave A]

this sudden burst of push-through regs (regarding this bonding issue) all of a sudden, and the dubious article published here (https://ecasa.co.za/technical/neutra...ing-clarified/) smells like an elastoplast plaster trying to fix the real issues, equipment not complying with SABS regs and standards.

Oh boy. The regulators can't win.
Sometimes they're accused of not being responsive and dragging their feet on issues. Other times they're accused of rushing through patch job changes to plaster over the cracks.

Can't we just accept that it is a relatively new issue in SA that we didn't have with backup generators, but has become a significant issue with the small scale (dare I suggest what should actually be called "micro scale") embedded generation rooftop PV segment that has flourished in the past few years.

It is actually a requirement that it should comply as a piece of equipment. - it does not. Part of the job of the inverter is to comply with the bonding regs - it does not.

And there is a manufacturer specified solution that falls in the category "as intended in the original design."
It is widespread practice to have standard patch solutions to cover the different situations a piece of equipment might find itself deployed into.

Or should we just have banned the Sunsynk inverters until the manufacturer built their solution option into the box?

[ACElectric]

Or should we just have banned the Sunsynk inverters until the manufacturer built their solution option into the box?

(or approve ones that complies with N/E bonding for alternative supplies as per sans) - in order to force the manufactures of a $$$$$$$ expensive inverter, to comply and fit a decent built in relay WITH a failsafe and warning system should there be issues with N/E bond, unlike now if the contactor fails the bond is lost - no warning)

But, i rest my case. My point is NOT getting across, one of my weak points i guess. Sorry about that.



last try....From now on we should be able to buy "approved" cbi plugs without an earth terminal, circuitbreakers wihout ratings, connect V-o-V gennies as long as we modify the gennie, (and certify it ourselves) and cars without brakes or wipers until the manufacturer builds it into the box.

anyway have a good day i am off on my ktm 1290 r for the weekend.

[Justloadit]

(or approve ones that complies with N/E bonding for alternative supplies as per sans) - in order to force the manufactures of a $$$$$$$ expensive inverter, to comply and fit a decent built in relay WITH a failsafe and warning system should there be issues with N/E bond, unlike now if the contactor fails the bond is lost - no warning)

But, i rest my case. My point is NOT getting across, one of my weak points i guess. Sorry about that.



last try....From now on we should be able to buy "approved" cbi plugs without an earth terminal, circuitbreakers wihout ratings, connect V-o-V gennies as long as we modify the gennie, (and certify it ourselves) and cars without brakes or wipers until the manufacturer builds it into the box.

anyway have a good day i am off on my ktm 1290 r for the weekend.

Depending on the generator, it has an earth terminal connection, it does not have an internal earth bond as per your statement, as an alternative supply, it requires an earth neutral bond for proper operation, which is done at the time of installation, just as with an inverter. There is no fail safe mechanism on the generator either. Not connecting Neutral to earth, will not trigger the ELU when there is an earth fault, and the reason for doing this when the inverter is in islanding mode.

[ACElectric]

""" Can you provide the reference to this statement in the regs please.""""



page 260 AS PER MY POST

[ACElectric]

""""Depending on the generator, it has an earth terminal connection, it does not have an internal earth bond as per your statement, as an alternative supply, it requires an earth neutral bond for proper operation, which is done at the time of installation, just as with an inverter. There is no fail safe mechanism on the generator either. Not connecting Neutral to earth, will not trigger the ELU when there is an earth fault, and the reason for doing this when the inverter is in islanding mode.""""

excuse me --- what statement??????

and yes, some generators (quite a lot) does have a permanent N/E bond directly on the winding side, built into the gennie.

I have been repairing generators before the dead sea was even sick and i have seen a lot of gennies in my 60 years with a permanent N/E bond INSIDE the gennie.

anyway - i see no use debating this further following this somewhat biased narrative.

good day.

[Justloadit]

""""Depending on the generator, it has an earth terminal connection, it does not have an internal earth bond as per your statement, as an alternative supply, it requires an earth neutral bond for proper operation, which is done at the time of installation, just as with an inverter. There is no fail safe mechanism on the generator either. Not connecting Neutral to earth, will not trigger the ELU when there is an earth fault, and the reason for doing this when the inverter is in islanding mode.""""

excuse me --- what statement??????

and yes, some generators (quite a lot) does have a permanent N/E bond directly on the winding side, built into the gennie.



I have been repairing generators before the dead sea was even sick and i have seen a lot of gennies in my 60 years with a permanent N/E bond INSIDE the gennie.

anyway - i see no use debating this further following this somewhat biased narrative.

good day.

[ATTACH=CONFIG]8894[/ATTACH]

Thank you for the photograph.
Interesting I had tested 2 large generators, and none have an earth Neutral bond so with this information, I made my post as you have highlighted "and yes, some generators (quite a lot) does have a permanent N/E bond directly on the winding side, built into the gennie."
So according to your statement, this mean that gennies with out the internal Earth Neutral bond do not comply.

Please note that we are all friends here from a vast number of backgrounds, and if a question is made, it is with intent of getting some information.
Debating is how we learn.

[Justloadit]

In reference to NRS-097-2-1-Published-2024, kindly provide by GCE in post #121, I have copied the following referring to inverters and Earth Netral Bonding

5.4 Neutral to earth bonding when forming an intentional island

5.4.1 To prevent a SSEG neutral connection to the the utility neutral through an earth conductor when the SDU opens, the SSEG shall not have a permanent neutral bonding to earth.
5.4.2 A hybrid system intended to form an intentional island on the load side during utility supply interruption shall open the SDU to prevent unintentional island on the utility side.
5.4.3 Since the SDU opens the neutral on the utility side, the intentional island neutral shall be bonded to earth within 200 ms after the SDU operation using a neutral to earth bonding unit (NEB).
5.4.4 The NEB shall open within a time period of 200 ms before the SDU reconnects the inverter to the utility supply.
5.4.5 The NEB shall consist of an electromechanical switching device rated at the nominal current rating of the inverter.
NRS 097-2-1:2024 12
5.4.6 The total clearance between the inverter neutral and earth conductors when the NEB is switched off, shall be equal the clearance of the SDU in its open state or more.
5.4.7 The NEB shall be an internal inverter component or an external device that is activated by a dedicated control port of the inverter.
5.4.8 The inverter data sheets shall indicate that it contains an internal NEB or a dedicated NEB control port for external devices.
5.4.9 Installation requirement: Inverters equipped with the NEB control port only, shall have external electromechanical NEBs installed that are SANS/IEC 60947-1 and SANS/IEC 60947-4-1 certified.

[Derlyn]

Question.

If one opens the back end of an alternator and finds the neutral and earth are bridged, how does one know when this bridging took place ?

Was it before the unit was sold as new, or was it done by someone like myself afterwards ?

Difficult to answer.

Does it matter ?

I say no. What matters is that it's there and it will ensure that a RCD in working order will do it's job and disconnect the supply should an earth fault occur. That's the important part.

The big problem with alternators is that the suppliers make no distinction between a portable unit and a standby unit. Here I'm referring to the smaller types that are sold at hardware stores to the general public and not the big diesel units used as standby units for whole shopping centres etc.

If one were to ask the salesman whether the unit you are eying to buy is a portable or standby unit, the chances are in the region of 99% that you'll get a blank stare reaction. Should you ask if the unit may be used as a standby unit at home, you will get a resounding "yes" even if it's VOV wound. All he wants to do is make the sale.

It is up to us, as electricians, to educate our clients as to the importance of certain procedures that need to be followed when doing a standby alternator installation. How many times has it not happened when quoting on a job that the prospective client questions why an earth spike at the alternator is necessary when his buddy down the road doesn't have one. I then explain with pen and paper and with the assistance of my reg book, why it's necessary. One or 2 days later I get a call from his buddy to come around and inspect his installation and do what's necessary to make it compliant and reasonably safe.

Anyway, just to end off, I am a toppie with many, I mean many domestic alternator installations under the belt and have yet to see a newly purchased alternator of 8Kw or smaller that has a permanent neutral earth bridge on the output. I've always had to do it myself. Hence my original question.

Have a super week ahead, all.

[Isetech]

I fit a changeover switch and breakers to suit the cable size, socket rating and changeover, I then a socket on the wall and what people plug into the socket is not my concern.

There is a notice above the socket ...

Do not plug in V-O-V generators.

Suitable for a 5 kva or what size the system was designed for a the time.

There is not much more you can do.

[Derlyn]

So this morning I was called out for an inverter tripping on overload intermittantly.

After much testing, I found that when the geyser is on, the output reading on the inverter goes up to over 4Kw even although the geyser is not fed by the inverter.

Whilst getting this reading of 4Kw, I put a clamp meter on the inverter output and it was only supplying 1,5 A (+-340W). The electronics of the inverter was somehow reading the current drawn by the geyser even although it was not supplying the geyser. It was time to call a friend.

The problem dissapeared when the permanent neutral earth bond on the inverter output was removed. As soon as it was replaced, the fault showed up again.

A couple more tests were done and it was found that everything was A ok when the earth neutral on the inverter is ONLY bridged whilst in islanding mode. The current in the earth neutral bridge was 10,5 Amps.

Anyway, thought I,d mention the above in case anyone comes across the same fault one day.

Moral of the story. DO NOT bridge the neutral earth on the inverter output permanently. Use a relay to perform this function when in islanding mode only.

Thanks for the assistance this morning Isetech. Much appreciated. And so we learn.