Neutral earth bonding on backup systems.

[Isetech]

I realise it is like flogging a dead horse, but reading posts of social media has highlighted this as a serious issue in the elctrical industry and we need to flog it until everyone agrees.

The AIA are saying one thing (a permanent bond id required) ,some of the the manufacturers say another thing (a relay is required), there is a higher percentage on the permanent bond side of the fence than the relay side of the fence.

My personal opinion - We need to install a relay which has built in protection to shut the down the system if the relay fails or the touch voltage is exceeded. My opinion is worthless, we need to clear this up with the powers that be and sooner than later.

[Isetech]

The question is who has the authority to clear up this mess? The DOL, the AIA, the ECA, the ECB, smart people on social media? (as silly as it sounds, this seems to be the solution at present)

From the interaction on this platform and many others, it is clear that the problem with the electrical industry, is not the willingness for people to learn, but the lack of technical support and herding, people tend to pick a side and just run with it, regardless if the solution is right or wrong.

With technology we have available in 2022, (its not 1980 anymore) technical support should be the least of of problems, yet here we sit in 2022 with people confused over a a silly thing like neutral/earth bonding. This people is a very concerning fact, and we wonder why the electrical industry is winning the race to the bottom. This people is why customers are prepared to pay "Technicians" like gate and alarm installers more than qualified electricians.

The stories I am hearing about how people get their qualifications and IE certificates is not helping the industry.

[GrahamH]

I have 3 concerns with the attached diagram:

2/ Some of the standby units have a common earth, they dont have LNE as terminal, only LN and common earth plate, so the note " Do not connect this terminal when the neutral wire and PE wire are connected together" cannot apply, It seems that someone just copied what they thought was the correct way to do it.

You're right, although my system has terminal points on the PCB where PE might be, but there are no connections on the PCB to the terminals. My leaning at the moment is to install a contactor to bridge the earth and neutral when the inverter is islanding and definitely not bridge the in and out neutrals as the diagram suggests. What I haven't figured out is how to make it fail-safe. I have ordered a good quality contactor than can do 30,000 cycles, but that is not a guarantee that nothing can go wrong. My neighbour has a similar system that was installed only 5 days ago and the contactor had a fault within two days. The technician replaced it apparently saying it was not a good brand but didn't say exactly what was wrong with it. IE open circuit or welded over.

[Derlyn]

It depends on what you want to make it fail safe against. If it is against contacts welding closed, you need 2 in series.
If it is against contacts not making, then you need 2 in parrallel.
The only way you gonna make it fail safe for both conditions is to have 2 strings of series contacts connected in parrallel ie. 4 relays.

Is it worth it ?

Rather oversize the contactor, use the best you can buy and trust it to do the job it was designed to do.

It's the same with earth leakage relays. The only way you can make them fail safe is to have 2 in series. Is it worth it ?

[Isetech]

I see pic of 10 amp finder relays being used to bridge the neutral/earth........eeeeish. Nothing surprises me anymore, the electrical industry is certainly in the lead when it comes to the race to the bottom. A combination of a lack of skills, no structure to control the industry, no leadership to guide the industry forward, the lack of common sense, the lack of product approval, no technical support combined with the almighty buck. I dont see it improving in my life time.

You're right, although my system has terminal points on the PCB where PE might be, but there are no connections on the PCB to the terminals. My leaning at the moment is to install a contactor to bridge the earth and neutral when the inverter is islanding and definitely not bridge the in and out neutrals as the diagram suggests. What I haven't figured out is how to make it fail-safe. I have ordered a good quality contactor than can do 30,000 cycles, but that is not a guarantee that nothing can go wrong. My neighbour has a similar system that was installed only 5 days ago and the contactor had a fault within two days. The technician replaced it apparently saying it was not a good brand but didn't say exactly what was wrong with it. IE open circuit or welded over.

[Isetech]

Or just have the correct equipment installed at the factory .

Leakage current protection, elevated voltage protection and what ever else is required to make the unit safe. Clearly leaving it up to a the installer to to make the right choice has proved to be a bigger challenge than anyone expected.

It depends on what you want to make it fail safe against. If it is against contacts welding closed, you need 2 in series.
If it is against contacts not making, then you need 2 in parrallel.
The only way you gonna make it fail safe for both conditions is to have 2 strings of series contacts connected in parrallel ie. 4 relays.

Is it worth it ?

Rather oversize the contactor, use the best you can buy and trust it to do the job it was designed to do.

It's the same with earth leakage relays. The only way you can make them fail safe is to have 2 in series. Is it worth it ?

[GrahamH]

[QUOTE=
The only way you gonna make it fail safe for both conditions is to have 2 strings of series contacts connected in parrallel ie. 4 relays.
[/QUOTE]

Funny I had exactly the same idea, however, you may only know that things have gone wrong when the last contactor also fails. I think that buying a good quality contactor is probably the best option. The one I am buying has a normally open and normally closed contact so maybe I can wire a led indicator light via the N/O contact which may help to check if the contactor is mechanically stuck closed. That will also serve as an indicator that we have load-shedding.

[GrahamH]

Funny I had exactly the same idea, however, you may only know that things have gone wrong when the last contactor also fails. I think that buying a good quality contactor is probably the best option. The one I am buying has a normally open and normally closed contact so maybe I can wire a led indicator light via the N/O contact which may help to check if the contactor is mechanically stuck closed. That will also serve as an indicator that we have load-shedding.

Ignore this post, I got my contacts the wrong way round

[Isetech]

I think the question we should be asking, which is the least dangerous option:

If you install a relay and it fails what is the worse thing that can happen?

If you install a permanent bond, what is the worse thing that can happen?

If it was that dangerous either way (permanent or relay), something would have been done about it by now. The poor suckers who are paying for the installations must be thinking, who is going to pay to make it right once the industry decides which method is right going forward, thats going to be the interesting part.

Apparently members of the AIA are threating court action if you fit a relay and the manufacturer is going to void your warranty if you dont fit a relay. Too much chatter and too little action. We cant blame the solar industry because the elctrical industry tried to take control of the solar installations, making a big noise about rules and regs, green cards, IE's and MIE's and now we cant even decide if a relay or a permanent bond should be used

[Dylboy]

With regards to the N E relay...

What size must it actually be ? I use 25A contactor with 4mm cable, sometimes 6.

In my eyes its to join them so that they are the same potential. No current is carried in the bridge other than in a Earth fault.

But some extra guideance would be great as I can't see in the book any thing abvious to me at the moment.


As I type this I think there is more to be discussed about how the bridge is done with what size relay and cable.



Sent from my CPH2197 using Tapatalk

[GCE]

I think the question we should be asking, which is the least dangerous option:

If you install a relay and it fails what is the worse thing that can happen?

Your protection may not operate , LED lights will glow with mains fail

If you install a permanent bond, what is the worse thing that can happen?

The house could catch fire if you suddenly become the earth neutral point for the minisub supplying the street

If it was that dangerous either way (permanent or relay), something would have been done about it by now. The poor suckers who are paying for the installations must be thinking, who is going to pay to make it right once the industry decides which method is right going forward, thats going to be the interesting part.

The regulations require that you fit a relay , there is no deciding that still has to happen

Apparently members of the AIA are threating court action if you fit a relay

On what grounds as the units that have the system fitted is just a Relay - Tesla for example

[GrahamH]

The regulations require that you fit a relay , there is no deciding that still has to happen

I completely agree with this and the guy who installed my neighbour's inverter told me that this became the rule recently. I would like to take this up with my installer, but they will argue and probably tell me that it will affect the warranty, so if possible, please could you refer us to where the regulation regarding this is published? Thanks in advance.

[Isetech]

This is the joke at the moment:

The manufacturer says you must fit a relay (but also say you have to comply with the local regs)

I hear the ECA technical team says you must use a relay. (this would need to be confirmed, this is just what I have read)

The DOL who is actually the big chief for electrical installations who uses the AIA as their voice in the industry and for technical support, and who you will have to answer to in court. Apparently I have read that they say you must do a permanent bond. If you are taken to court they will interpret the regulations as per all the relevant SANS codes for the DOL.

There is a poll on social media, which indicates that more than 70% of inverter installations in SA have permanent bonds and only around only 30 % have a relay.

I stand to be corrected but I believe the majority vote on this platform is to install a relay.

Did someone mention grey area

I completely agree with this and the guy who installed my neighbour's inverter told me that this became the rule recently. I would like to take this up with my installer, but they will argue and probably tell me that it will affect the warranty, so if possible, please could you refer us to where the regulation regarding this is published? Thanks in advance.

[GCE]

I completely agree with this and the guy who installed my neighbour's inverter told me that this became the rule recently. I would like to take this up with my installer, but they will argue and probably tell me that it will affect the warranty, so if possible, please could you refer us to where the regulation regarding this is published? Thanks in advance.

Not sure about the recent ruling but suppose that is interpretation - Has been out since at least 2008
Do not see how it can have an effect on the warranty - It has to comply otherwise you cannot use it into a fixed electrical installation - Then it should only have been used as a portable unit.

SANS 10142-1:2021
Edition 3.1
7.12 Alternative supplies
NOTE Alternative supplies include but are not limited to low-voltage generating sets,
photovoltaic (PV) installations, gas generators, diesel generators, wind turbines and
hydropower plant.

7.12.3.1 Neutral bar earthing
7.12.3.1.1 Protection in accordance with the requirements of 6.7 shall be
provided for the electrical installation in such a manner as to ensure correct
operation of the protection devices, irrespective of the source of supply or
combination of sources of supply. Operation of the protection devices shall
not rely upon the connection to the earthed point of the main supply when the
generator is operated as a switched alternative to the main supply.



SANS 10142-1:2008
Edition 1.1
(As amended 2003 and 2008)
7.12.3 Earthing requirements and earth leakage protection
7.12.3.1 Neutral bar earthing
7.12.3.1.1 Protection in accordance with the requirements of 6.7 shall be
provided for the electrical installation in such a manner as to ensure correct
operation of the protection devices, irrespective of the source of supply or
combination of sources of supply. Operation of the protection devices shall
not rely upon the connection to the earthed point of the main supply when the
generator is operated as a switched alternative to the main supply.
Amdt 6

[GCE]

This is the joke at the moment:

The manufacturer says you must fit a relay (but also say you have to comply with the local regs)

I hear the ECA technical team says you must use a relay. (this would need to be confirmed, this is just what I have read)

The DOL who is actually the big chief for electrical installations who uses the AIA as their voice in the industry and for technical support, and who you will have to answer to in court. Apparently I have read that they say you must do a permanent bond. If you are taken to court they will interpret the regulations as per all the relevant SANS codes for the DOL.

There is a poll on social media, which indicates that more than 70% of inverter installations in SA have permanent bonds and only around only 30 % have a relay.

I stand to be corrected but I believe the majority vote on this platform is to install a relay.

Did someone mention grey area

Some inverters you have to bond permanently - I have an imeon that the output is isolated from mains and has to be permanetly bonded - Others are not permanenly isolated from mains and you therefore need to use a relay.
Tesla only bonds earth neutral when in mains fail mode
The AIA cannot change regulation - 6.1.6 - Been there , done it , have the T-shirt

6.1.6 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 except as
allowed in 7.16.4