NiyiOmoIyunade:
Zeal for the Lord's work ni o.

And the very faint hope that someone somewhere will benefit and all the sermonizing will help them do things right or avoid disaster.

Well done!

This image you posted - I am struggling to see the relevance to PV protective earthing.

As for the NEC expose on youtube, I am fairly sure responses to youtube comments as the authority for best practice will be dimly regarded by home insurance and the code compliance inspector. If you could reference the actual NEC codes you are referring to as support for your position that would be nice - the ones you have paraphrased here are almost exactly the best practice I have been preaching.

The codes are not nice to haves but actually mandatory compliance requirements for a facility to pass inspection and qualify for insurance - try claiming insurance when lightning has damaged your property and you are unable to demonstrate code compliance and watch the claim thrown out. Here in Nigeria we do whatever we like, get lucky because we did not suffer an actual hit and call ourselves experts on doing it right.

Please read the things I said and see if you have issue with any particular one then we can discuss that very one in detail - to my mind it appears there is some conflation between connecting the designated earth point and chassis of equipment and frames of exposed outdoor objects to protective earth (Earthing) vs connecting the AC neutrals and DC negatives together or to thesame earth point (Grounding) and sadly these terms are also used loosely and interchangeably.

There is a limited number of cases where one may setup his PV protective earth and keep it isolated from the main facility earth and the codes cover these as well - these are more exceptions than the norm.

Again, let us leave quoting arcane references to code and pick one actual scenario or problem and we can work out the merits of various approaches strictly based on the risk vs protection trade offs the alternative approaches offer.

jonescosmo:
NEC has a Youtube handle where they constantly review codes with practical illustrations. Don't forget to search for them and see things for yourself. Some of sub codes of Code 250 illustrates grounding for transformers this code was in 2013/2013 thereabout revised in Code 690.70 with the evolution of Inverters and PVs. It became an issue for code 250s and 690s because the countered each other.

You will find out that Codes of PV groundings are constanlty being reviewed after some lightening related incidents had already done damages. they will speak all the grammars to defend the former code and also issue a revised code countering the former.

Someone asked in one of the videos:
"Remember that Codes about Earthing has been written a long time ago when we didn't have PV Panels, even if they existed it was not like what we have in the present scale, Are you saying we should just put our PV up the roof and hook the grounds to our house ground?"

The answer to that was:
"While research has continued in this topic, Yes you can hook them to your house ground but best practice is to rather hook them to you arrestor's earth pole which is not the same as your electrical appliances earth. Anything mounted high up on your is considered as a lighthening receptor but if their Earth electrodes are less than 6feets apart, then there is no need for a second earth electrode and all Bonding must happen deep under the ground."

For those of us who have access to NEC codes articles, do yourself a favour by understanding how stuff works from your findings. So that you will not base your knowledge on personal assumptions.

FOR MY PERSONAL EXPERIENCE, I think I will follow the millions in the crowd who says while i have the CODES, I will take things a bit farther so protect my stuff. you can do your findings from videos and co see what people are doing in real life and not base on theories.

The image below was from one of NECs presentations. Since I have[b] Zero Reference[/b] to my claims.

NiyiOmoIyunade:
This image you posted - I am struggling to see the relevance to PV protective earthing.

As for the NEC expose on youtube, I am fairly sure responses to youtube comments as the authority for best practice will be dimly regarded by home insurance and the code compliance inspector. If you could reference the actual NEC codes you are referring to as support for your position that would be nice - the ones you have paraphrased here are almost exactly the best practice I have been preaching.

The codes are not nice to haves but actually mandatory compliance requirements for a facility to pass inspection and qualify for insurance - try claiming insurance when lightning has damaged your property and you are unable to demonstrate code compliance and watch the claim thrown out. Here in Nigeria we do whatever we like, get lucky because we did not suffer an actual hit and call ourselves experts on doing it right.

Please read the things I said and see if you have issue with any particular one then we can discuss that very one in detail - to my mind it appears there is some conflation between connecting the designated earth point and chassis of equipment and frames of exposed outdoor objects to protective earth (Earthing) vs connecting the AC neutrals and DC negatives together or to thesame earth point (Grounding) and sadly these terms are also used loosely and interchangeably.

There is a limited number of cases where one may setup his PV protective earth and keep it isolated from the main facility earth and the codes cover these as well - these are more exceptions than the norm.

Again, let us leave quoting arcane references to code and pick one actual scenario or problem and we can work out the merits of various approaches strictly based on the risk vs protection trade offs the alternative approaches offer.

I think enough is been said on this topic already let's drop it.
At least people have gotten the message in relation to many different scenarios and they can decide exactly what to follow.

Electrical Codes are there in the open. People should go scroll through most of them that have covered Earthing or Grounding and deduct their methods accordingly.

For me whenever I acquire any electrical gadget I always look at the conformities first before installing them and if there are modifications I need to make to my existing installations, I make them. And then I will compare what changed from the prior conformities.
Some people might be stuck in the past with a certain information on their minds without knowing that things have changed a bit from what it used to be.

Enough on this topic bros. Except someone asks for recommendations or directions.

I bow out. We move,

NiyiOmoIyunade:
I did a long response that made me sef tired

But a shorter rejoinder is below

Protective Earths and Earthing - Solidly connect all buried earth electrodes together at your facility be they electrodes for PV earth, lightning protection earth or general earth. This creates an overall better fault sink (lower combined resistance) and eliminates voltage gradients between isolated buried electrodes that could damage equipment and harm personnel.


Zero Reference Grounding - Do not connect either of AC neutral or DC negative to each other and do not connect AC neutral and DC negative to the same protective earth.

Do not connect DC negative to any protective earth at all - rather connect the chassis frame or ordinarily non current carrying part of the equipment to protective earth.

AC grounding - connecting the AC neutral to protective earth - should only be done when supported by the electrical network and all your connected equipment and is/has become a requirement for enhanced personnel and equipment safety.

Chassis and frame grounding - should be done in all cases - connect the chassis of your major energy generators and processors to protective earth - test for full isolation between the chassis and AC neutral and also between the chassis and DC negative before making the chassis to protective earth connection to avoid unintended behaviours.

Designated equipment earth point to protective earth - do in all cases. Do same checks as chassis and frame grounding above so that the system can behave in a predictable manner.

PV frame and mounting rack to protective earth - connect directly to the earth electrode or worst case the earth service bus bar

Seriously, why are both of you doing this to us, you just drive my brains like "it's convayed in a roller coaster" �. But was a nice read from both of you...

I see both of you still have alot to contribute to this particular subject matter, for me, one take home is "Do not connect DC negative to any protective earth at all" and now it's clearer.

Why dont we have a space on Twitter and have a real talk on all of these please... I know Niyi still has a lot to pour out...

But to be honest Niyi, sometimes your choice of words, I know they are the right vocabs and terminologies, but I really get lost reading your articles and then I have had to call you to get them expressed better in words and this is why I think Twitter space will help all of us understand even much more what you have explained in writting. Mr Niyi, please open one, could be late evenings and I sure will be one of your listeners....

Kudos guys!

Please where can I walk in physically to buy DC ceiling fans?

odimbannamdi:


Please, how can this be resolved? Is earthing really the issue and what can we do? Also, what is likely to have spoilt in the inverter? I just weak...something wey I no even charge them, based on hobby and relationship waka, i now lost a precious inverter...

Thanks for your contribution, guys. I sincerely appreciate.

So, i have opened up the inverter and discovered that one of the 4 output mosfets is burnt. First and second attached pictures show the damaged mosfet. The mosfet is S60N12R B (in third pic). I reached out to a technician in Arena about it, but he said that particular mosfet is scarce, that i could use mosfet Irf 740 (in fourth pic). He advised that, if i decide to use the Irf 740, i will have to change all 4 output mosfets as well so it doesnt spoil again.

Guys, please what do you advise? I do not exactly have the luxury of time to order for the mosfet from Aliexpress

Please guys is it safe to use 350W Jinko Panel * 4 (i.e 1400W) in 24v system using MakeSkyBlue 60A CC, considering the CC Max allowed Watts @24v is 1440W?

NiyiOmoIyunade:
For permanent good results, it is better to use a suitable GEM premix in place of animal dung, salt, charcoal etc.

A good GEM premix properly applied will create a very stable low resistance earth for several years with no need to do any topups or further work

See example picture below

Thanks for weighing in, Oga Niyi.

But, just out of curiousity, aside this incidences of inverters getting damaged, are there other disadvantages or risks of improper earth connection like in the case i stated earlier?

Then, are there significant advantages of having a proper earth connection as well?

TechGeek777:
Please guys is it safe to use 350W Jinko Panel * 4 (i.e 1400W) in 24v system using MakeSkyBlue 60A CC, considering the CC Max allowed Watts @24v is 1440W?

I guess so.

I use 2 units of 540w Jinko panels (1080w) on a 12v connection with Powmr (similar to MSB), even though the max PV input power for 12v is 720w. I was so scared that the CC would fry when the sun peaks, but it is still holding up well.

I think there is tolerance allowance. And as long as you dont exceed the max VOC, you should be fine.

odimbannamdi:


I guess so.

I use 2 units of 540w Jinko panels (1080w) on a 12v connection with Powmr (similar to MSB), even though the max PV input power for 12v is 720w. I was so scared that the CC would fry when the sun peaks, but it is still holding up well.

I think there is tolerance allowance. And as long as you dont exceed the max VOC, you should be fine.

Wow that's impressive, I was initially planning to use 400W jinko, but fear of the CC getting damage as stated by the manufacturer is while I consider 350W.

I understand the VOC should not be more than 105v @24v.

Jinko 400W VOC is 49.8v @STC.

Could it also be safe to use Jinko Half Cut 400W * 4 (1600W) same @24v with Makeskyblue 60A?

Also have your Powmr ever produce above 800W?

I guess I need to learn to communicate better or say much less or both

+100 for not connecting DC negative to earth in any scenario - it can only help in limited cases and always increases the risk of catastrophic failure by a large amount when things go wrong.

contease:


Seriously, why are both of you doing this to us, you just drive my brains like "it's convayed in a roller coaster" �. But was a nice read from both of you...

I see both of you still have alot to contribute to this particular subject matter, for me, one take home is "Do not connect DC negative to any protective earth at all" and now it's clearer.

Why dont we have a space on Twitter and have a real talk on all of these please... I know Niyi still has a lot to pour out...

But to be honest Niyi, sometimes your choice of words, I know they are the right vocabs and terminologies, but I really get lost reading your articles and then I have had to call you to get them expressed better in words and this is why I think Twitter space will help all of us understand even much more what you have explained in writting. Mr Niyi, please open one, could be late evenings and I sure will be one of your listeners....

Kudos guys!

TechGeek777:



Wow that's impressive, I was initially planning to use 400W jinko, but fear of the CC getting damage as stated by the manufacturer is while I consider 350W.

I understand the VOC should not be more than 105v @24v.

Jinko 400W VOC is 49.8v @STC.

Could it also be safe to use Jinko Half Cut 400W * 4 (1600W) same @24v with Makeskyblue 60A?

Also have your Powmr ever produce above 800W?

I am scared of answering the question in your penultimate sentence, make you no find me come house... ...but going by my current set up, I would do so if I were in your shoes.

In fact, I actually have 4 units of 540w on my roof, but I have only 2 connected since I am on a 12v connection. When I upgrade to 24v and connect all 4 units, I should be doing x2 of what i am currently doing now, on the same CC. But, let more experienced folks give their advise as well.

As to the last question in your last sentence, yes it should. I have observed it do 762w before, so it is very likely to have done 800w and more. I don't always observe it

The protective earth is there for safety - it is inert and does no work until a surge hits or a local fault occurs and then it offers a path of least resistance through the system so that the fault or surge can pass through and be sunk into earth without damaging the equipment - With a proper protective earth in place, one can further add SPDs to speed the surge or fault away from the protected system and limit the voltage rise seen by the protected equipment.

An example of a local fault is when a live wire touches the chassis of a piece of equipment or other such mistake or fault energises the case - proper protective earth connection will prevent someone coming in contact with the now live chassis from being electrocuted.

So yes your equipment and energy generators/processors should all be connected to protective earth at the very least or else they are unprotected from an incoming surge or local fault.

There are 3 major external ingress points for surges to hit a facility

1) From the mains incoming line - the service wires carrying power from the national grid to local street transformers are like huge antennas for lightning, although these are usually connected to protective earth at various points in the network and the transformer, large enough transients can pass through and damage appliances in a facility - best option is a good protective earth in place and SPDs on the mains incomer as well

2) Nearby hits and induced surge in cables and metal objects in the facility - all exposed outdoor metal (generators, antennae, dstv dish, solar panels, comms and power cables etc) can pickup induced surges when lightning strikes nearby - this is why it is recommended to connect them all to protective earth so that the surge can sink safely

3) Direct hit to building or exposed objects - this is a force majeure item so expect total obliteration and give thanks if you escaped with your life - there is really no protection against a direct hit.

However a mitigant to direct hits are early streamer devices mounted atop the facility - these will pickup surges while still at the early stages and send them to the protective earth

So if you have panels with your inverter then your risk increases as the panels can pickup static electricity or some surge transients and pass them through your system - a common failure mode for poorly earthed or unearthed systems in overnight rain accompanied by lightning strikes and the homeowner wakes up to a dead inverter - this damage easily avoided with a proper earth connection in place. You also do not want your equipment to electrocute someone or cause a fire where a few rods sunk in the earth would have saved the day.

For your inverter that burnt a FET I cannot say what the root cause was - looks more likely to be overload - most line surges damage the input stage.

odimbannamdi:


Thanks for weighing in, Oga Niyi.

But, just out of curiousity, aside this incidences of inverters getting damaged, are there other disadvantages or risks of improper earth connection like in the case i stated earlier?

Then, are there significant advantages of having a proper earth connection as well?

Good day,

Please recommend a very good 100amps lead acid battery.

Yes. Connect it in 2p2s. Ie connect 2 pairs in parallel n connect the pairs in series. If d panel nah 500w say 50v 10a. U'll av 100v 20a flowing through ur wire. Make sure u check ur panel max series fuse. N use the rated fuse for d penels Incase there is a short. So ur panels can b safe.

TechGeek777:
Please guys is it safe to use 350W Jinko Panel * 4 (i.e 1400W) in 24v system using MakeSkyBlue 60A CC, considering the CC Max allowed Watts @24v is 1440W?

I remember this cracked panels, I was scared to buy den.

odimbannamdi:


I am scared of answering the question in your penultimate sentence, make you no find me come house... ...but going by my current set up, I would do so if I were in your shoes.

In fact, I actually have 4 units of 540w on my roof, but I have only 2 connected since I am on a 12v connection. When I upgrade to 24v and connect all 4 units, I should be doing x2 of what i am currently doing now, on the same CC. But, let more experienced folks give their advise as well.

As to the last question in your last sentence, yes it should. I have observed it do 762w before, so it is very likely to have done 800w and more. I don't always observe it

NiyiOmoIyunade:
Zeal for the Lord's work ni o.

And the very faint hope that someone somewhere will benefit and all the sermonizing will help them do things right or avoid disaster.

Honestly am enjoying education argument am actually learning a great lot from both of them, even though they contradicting each other

odimbannamdi:


I am scared of answering the question in your penultimate sentence, make you no find me come house... ...but going by my current set up, I would do so if I were in your shoes.

In fact, I actually have 4 units of 540w on my roof, but I have only 2 connected since I am on a 12v connection. When I upgrade to 24v and connect all 4 units, I should be doing x2 of what i am currently doing now, on the same CC. But, let more experienced folks give their advise as well.

As to the last question in your last sentence, yes it should. I have observed it do 762w before, so it is very likely to have done 800w and more. I don't always observe it

Thanks

Jefferyzz:
Yes. Connect it in 2p2s. Ie connect 2 pairs in parallel n connect the pairs in series. If d panel nah 500w say 50v 10a. U'll av 100v 20a flowing through ur wire. Make sure u check ur panel max series fuse. N use the rated fuse for d penels Incase there is a short. So ur panels can b safe.

Noted with thanks, since 380W won't cause damage that's what am going for.

It has Isc of 10.77a, Max series fuse rating of 20A, with 2p2s that will be (10.77 * 2 = 21.54A).

Do you think 30A fuse will be too much or should I stick with manufacturer recommendation of 20A fuse?

I wanted to ask, but I guess this is the right time.

Should those electricians who like to cut off the earth wires of electrical equipment be executed for malpractice?

That was harsh, I meant to say should they be charged with malpractice?

FEGEITOK:
I wanted to ask, but I guess this is the right time.

Should those electricians who like to cut off the earth wires of electrical equipment be executed for malpractice?

That was harsh, I meant to say should they be charged with malpractice?

I'll chip in - One good (or bad) cut deserves another
Should those electricians who like to cut off the earth wires of electrical equipment be castrated for malpractice?

They should be guillotined - my current location the electrician was paid for 4mm2 wire for all AC and heater lines, enough to cover both Live and Neutral and Earth wires, he switched the Earth wires to 1.5mm2 because 'he felt 4mm2 was overkill'. I fired him immediately I discovered the breach and got him to pull out the 1.5mm2 and deliver the 4mm2 he was paid for. Yes 4mm2 earth wire per AC is overkill but na code be that (to match the main conductors), na wetin I want be that and na wetin I pay for be that.

A recent job, the client had AC neutral wire looped to some lighting points, reco to separate the wires and the electrician goes to use the existing 2.5mm2 for the lights and 1.5mm2 for the AC 'because he only saw 1.5mm2 to buy'

I quietly texted the client to better go find a proper electrician else I would just hands off support.

Electricians really do the most and it is so difficult to find a half decent one. Most do not even have a basic multimeter for any informed troubleshooting.

FEGEITOK:
I wanted to ask, but I guess this is the right time.

Should those electricians who like to cut off the earth wires of electrical equipment be executed for malpractice?

That was harsh, I meant to say should they be charged with malpractice?

NiyiOmoIyunade:
They should be guillotined - my current location the electrician was paid for 4mm2 wire for all AC and heater lines, enough to cover both Live and Neutral and Earth wires, he switched the Earth wires to 1.5mm2 because 'he felt 4mm2 was overkill'. I fired him immediately I discovered the breach and got him to pull out the 1.5mm2 and deliver the 4mm2 he was paid for. Yes 4mm2 earth wire per AC is overkill but na code be that (to match the main conductors), na wetin I want be that and na wetin I pay for be that.

A recent job, the client had AC neutral wire looped to some lighting points, reco to separate the wires and the electrician goes to use the existing 2.5mm2 for the lights and 1.5mm2 for the AC 'because he only saw 1.5mm2 to buy'

I quietly texted the client to better go find a proper electrician else I would just hands off support.

Electricians really do the most and it is so difficult to find a half decent one. Most do not even have a basic multimeter for any informed troubleshooting.

They installed my A/C and cut off the earth wires. My brand new Daikin A/C. Correcting it first thing on Monday.

Thanks a million

FEGEITOK:
I wanted to ask, but I guess this is the right time.

Should those electricians who like to cut off the earth wires of electrical equipment be executed for malpractice?

That was harsh, I meant to say should they be charged with malpractice?

I'm not sure many of our artisans are actually registered.

NiyiOmoIyunade:
They should be guillotined - my current location the electrician was paid for 4mm2 wire for all AC and heater lines, enough to cover both Live and Neutral and Earth wires, he switched the Earth wires to 1.5mm2 because 'he felt 4mm2 was overkill'. I fired him immediately I discovered the breach and got him to pull out the 1.5mm2 and deliver the 4mm2 he was paid for. Yes 4mm2 earth wire per AC is overkill but na code be that (to match the main conductors), na wetin I want be that and na wetin I pay for be that.

A recent job, the client had AC neutral wire looped to some lighting points, reco to separate the wires and the electrician goes to use the existing 2.5mm2 for the lights and 1.5mm2 for the AC 'because he only saw 1.5mm2 to buy'

I quietly texted the client to better go find a proper electrician else I would just hands off support.

Electricians really do the most and it is so difficult to find a half decent one. Most do not even have a basic multimeter for any informed troubleshooting.

Oga niyi how do I start studying this electrical codes.

Am a student (marine engineering) am aiming at focusing on marine electrical /electronics systems.

We are actually not so far apart - Oga J believes he will get more safety from an isolated PV earth - I believe he is better off creating an equipotential bond across all buried earth electrodes both because he gets a much bigger fault sink with the combined earth electrodes and also because he would eliminate the risk of step/fall potential killing people walking between two isolated earth rods and also surge induced voltage gradients between the rods creating a fault condition/loop that could damage the very equipment he was trying to protect.

Electrical code looks at all the possible fault and failure modes and selects the approach that guarantees the most favorable outcomes for personnel and secondarily equipment in the most likely to occur fault and failure scenarios - in simple English a lot of modelling and assumptions and educated guess work goes into making the codes up so they are not infallible nor do they cover all possibilities, only the likely or feasible scenarios.

In practice an isolated PV protective earth would be reasonably effective both because the solar panels did not take a too massive hit and also because the sunken rods are sufficient to sink whatever faults hit them. If a larger fault than the isolated earth rods could sink happens then the risk I mentioned that the codes are trying to guard against crystallises.

As you see so many ifs and possibilities - in practice luck and time and chance play a big role so a totally unearthed building could go for years unscathed and someone who did it 100% right or 80% right could still suffer catastrophic damage. The luck of the draw plays a major role in the outcomes we get.

Prince3:


Honestly am enjoying education argument am actually learning a great lot from both of them, even though they contradicting each other

Yh. Stick to the manufacturer max fuse

TechGeek777:


Noted with thanks, since 380W won't cause damage that's what am going for.

It has Isc of 10.77a, Max series fuse rating of 20A, with 2p2s that will be (10.77 * 2 = 21.54A).

Do you think 30A fuse will be too much or should I stick with manufacturer recommendation of 20A fuse?

TechGeek777:


Noted with thanks, since 380W won't cause damage that's what am going for.

It has Isc of 10.77a, Max series fuse rating of 20A, with 2p2s that will be (10.77 * 2 = 21.54A).

Do you think 30A fuse will be too much or should I stick with manufacturer recommendation of 20A fuse?

You will need two of the 20A fuse. One for each series connection

NiyiOmoIyunade:
The protective earth is there for safety - it is inert and does no work until a surge hits or a local fault occurs and then it offers a path of least resistance through the system so that the fault or surge can pass through and be sunk into earth without damaging the equipment - With a proper protective earth in place, one can further add SPDs to speed the surge or fault away from the protected system and limit the voltage rise seen by the protected equipment.

An example of a local fault is when a live wire touches the chassis of a piece of equipment or other such mistake or fault energises the case - proper protective earth connection will prevent someone coming in contact with the now live chassis from being electrocuted.

So yes your equipment and energy generators/processors should all be connected to protective earth at the very least or else they are unprotected from an incoming surge or local fault.

There are 3 major external ingress points for surges to hit a facility

1) From the mains incoming line - the service wires carrying power from the national grid to local street transformers are like huge antennas for lightning, although these are usually connected to protective earth at various points in the network and the transformer, large enough transients can pass through and damage appliances in a facility - best option is a good protective earth in place and SPDs on the mains incomer as well

2) Nearby hits and induced surge in cables and metal objects in the facility - all exposed outdoor metal (generators, antennae, dstv dish, solar panels, comms and power cables etc) can pickup induced surges when lightning strikes nearby - this is why it is recommended to connect them all to protective earth so that the surge can sink safely

3) Direct hit to building or exposed objects - this is a force majeure item so expect total obliteration and give thanks if you escaped with your life - there is really no protection against a direct hit.

However a mitigant to direct hits are early streamer devices mounted atop the facility - these will pickup surges while still at the early stages and send them to the protective earth

So if you have panels with your inverter then your risk increases as the panels can pickup static electricity or some surge transients and pass them through your system - a common failure mode for poorly earthed or unearthed systems in overnight rain accompanied by lightning strikes and the homeowner wakes up to a dead inverter - this damage easily avoided with a proper earth connection in place. You also do not want your equipment to electrocute someone or cause a fire where a few rods sunk in the earth would have saved the day.

For your inverter that burnt a FET I cannot say what the root cause was - looks more likely to be overload - most line surges damage the input stage.

Thank you very much for this insightful and details response, Oga Niyi.

Jefferyzz:
Yh. Stick to the manufacturer max fuse

Noted thanks

coldcandy:


You will need two of the 20A fuse. One for each series connection

Noted thanks

Hello solar gurus, sorry to disrupt your earthing argument. I have another argument myself that ensued between me and a installer this evening. I was lamenting about the 40% drop of amps from my panels this dry season to him and suspected the culprit to be dust & heat combined.

To my surprise, he insisted that dust was a minor factor reducing my panel output. He diagnosed my failing battery as the major factor for the amps drop.

So please, is there any way a weak battery can result to lesser output from my panels?