Class 11 equipment

[Isetech]

For those who dont know the differecne between class 1 and calss 11 equipment.


"What is the difference between Class 1 and Class 2 electrical safety?
Class I Equipment is protectively earthed. All conductive parts are connected to an Earth Wire that has a continuous circuit through to the Earth Pin on the plug. All Appliance Testers will carry out this test. Class II Equipment is Double Insulated and does is not required to be earthed."

The question is do you need to earth solar panels and why, considering they are class 11 equipment.

Then the next question would be if they are class 11 equipment why you would need to bond a metal roof because you have fitted, considering the leads and solar wire is also double insulated and generally fitting in a PVC raceway. Some would say any roof with a supply connection to the roof would require it to be earthed and bonded.

What are your thoughts on this topic.

We all know what the regualtions state, I can copy and paste a bunch of regualtion from the SANS if thats what you need a quick, but I want to hear your thought on this topic.

[Derlyn]

This is my take.

There are 2 reasons why mettalic parts need to be earthed.
A) So that protective gear, be it on the supplier side or consumer side can function correctly in the event of an earth fault.
B) To discharge any static buildup to earth.

Even although panels might be class 2, there is metal involved where a static build up can occur, hence the need to bond and earth them.

[Dylboy]

My thing is we now bonding a DC item to AC.

So if it is for static which I think is good then it must go straight to the actual earth and no where near the AC side, even though earth is earth.

Imagine now a DC fault on the panel going to the Earth of the AC installation and blinding the RCDs or having high DC voltage/current on all metal parts. I guess the negative side is not joined to earth.

Bonding is for the Faraday cage.



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[Derlyn]

My thing is we now bonding a DC item to AC.

So if it is for static which I think is good then it must go straight to the actual earth and no where near the AC side, even though earth is earth.

Imagine now a DC fault on the panel going to the Earth of the AC installation and blinding the RCDs or having high DC voltage/current on all metal parts. I guess the negative side is not joined to earth.

Bonding is for the Faraday cage.



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You said it yourself, my brother ....... earth is earth.

Earth is a big round ball, rotating once on its own axis every 24 hrs and once around the sun each year.

There is no AC earth and DC earth. There's only one earth and that is earth.

[Isetech]

By earthing or bonding the panel are you installing lightning protection which should be installed as per the regulations for lightning protection or are you earthing/bonding for faults between the frame and the double insulated cells?

Lets not complicate it with a metal roof for now, lets focus on a standard nonmetalic tiled roof.

Why are we earthing/bonding a class 11 double insulated product which doesnt require an earth?

If the product requires and earth why are they not fitted with a tail that can link together to create a low resistance path, like an MC 4 connector or the like?

I have noticed that they have an earth screw hole.

[Isetech]

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I have looked at fitting earth tails on the panels which will connect from the panel to the rail with a lugs on the centre or end support.

The problem is that "all" the components of the rail are anodised which results in a high resistance, to create a good bond you need to damage the anodising by removing the protective layer on the aluminium, to create a low resistance path. On the coast this is going to create a bigger problem.

Then you have the combination of S/S and aluminium which is going to also create a few challenges.

I found grounding lugs which did the trick, but like everything solar related, once I have purchased the first batch, there is now a stock availability issue

[Dylboy]

Everything in your last 2 posts I agree with you 100% and I have the same thoughts.... It is absolutely ridiculous that we don't have a solid answer to such basic questions

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[Isetech]

After doing some research, I think the best way to earth/bond the panels is to fit a grounding clamp which fits into the hole marked earth (drilling holes into the frame void the panel warranty) on the panel and run one piece of wire, which is not cut from the one side of the panels to the opposite side then attach both ends to the rail. From the rail down to the DC combiner/control box, then from there to the earth spike. You could also zig zag the wire and attach the grounding lug to the rail.
If the roof is metal you could attach a tail from the end of the rails to the metal roof, bringing it all to the same potential, in reality that is what you are trying to achieve.
I need to check a panel, but if I recall the earth is close to the middle of the panel, it would be better if the earth is closer to the top or bottom depending on the panel location in relation to the string layout. It must be easily accessible once the panels are installed.

A line tap with a screw to attach it to the frame would be the best option, the reason I say this is because the other methods use a screw which can cut into the wire if it is not secured with a torque screwdriver to only around 2.0 nm

If you need to remove one panel, you loosen the nuts securing the wire and lift the panel.

By doing it like this you create a bond between all the panels and each end of the rail (which is exposed), you don’t rely on the rail for the bond, the rail below the panels are not exposed, but will still be bonded even if you have a splice linking 2 rails which might not been bonded correctly, creating a bad high resistance further down the rail.




Look at the device on page 11, top right picture, it looks like a line tap, not a screw to damage the wire, especially if you use house wire or any multi strand wire.

https://www.jasolar.com/uploadfile/2022/0218/20220218094931164.pdf

[Isetech]

I think it is important to understand what it is that you are trying to achieve, lightning protection or create a low impedance path to ground in case of a fault or elevated potential difference between the metal components.

The question: do you need to earth a piece of equipment which has a class 11 safety rating, you can’t, because it is double insulated, then should you earth all the metal around the piece of equipment, maybe not such a bad idea, even though the wire is not touching the frame, it is connected to the insulated part of the panel using double insulated wire into a plastic enclosure attached to the double insulated part of the panel.
You would need to take a few other factors into account, like touch voltage, damaged cabling during installation which could create a potential difference and all that kind of stuff.

[Isetech]

Grounding, bonding or earthing, all the same thing ? You might be suprised by the answer you get form most "electricians"

If you look under section 6.12 Earthing and 6.13 bonding, 2 seperate section in the code.

Then you got section 6.7.6 ....Annex I which goes into surge and lightning protection.

People will say, but why dont elctricians read the book, simple, the customer and employers dont see electricains reading silly regulations as part of their job, they should be standing with a scredriver or some tool in hand making money for the comapny, not sitting around reading books.

YOu want to improve the state of the industry, allow elctricians to read the regualtions, create non compliant lists which include referecne to the code and like the tool talk in the morning, regualtions related to the project for the day should be inculded.

Once an elctricans reaches he level of SPT, IE or MIE, they should be spending alot less time with a tool in hand, but rather checking the work being done by labourers to electricans is to code, refresher course gaining points like engineers have to do and testing parts of the installation before being powered up.

[Isetech]

Grounding....as refered to in installation manuals

https://en.wikipedia.org/wiki/Ground_(electricity)

[Isetech]

Before you decide to install a solar panel and start running earth wires all ove rthe place, makes sure you understand what it is you are trying to achieve, are you earthing the panel, bonding (grounding as recommended in the installtion manuals) the panel or installing lightning protection?

Then design and install the wire (whatever it is you call the green and yellow wire) as require by the regs applicable to to the design.

Something else to consider, if you are installing "lightning protection" then there is anotehr can of worms you need to consider, with regards to class 1 and class 2 lightning protection, but we will look at that another day.

[GCE]

For those who dont know the differecne between class 1 and calss 11 equipment.


"What is the difference between Class 1 and Class 2 electrical safety?
Class I Equipment is protectively earthed. All conductive parts are connected to an Earth Wire that has a continuous circuit through to the Earth Pin on the plug. All Appliance Testers will carry out this test. Class II Equipment is Double Insulated and does is not required to be earthed."

The question is do you need to earth solar panels and why, considering they are class 11 equipment.

Then the next question would be if they are class 11 equipment why you would need to bond a metal roof because you have fitted, considering the leads and solar wire is also double insulated and generally fitting in a PVC raceway. Some would say any roof with a supply connection to the roof would require it to be earthed and bonded.

What are your thoughts on this topic.

We all know what the regualtions state, I can copy and paste a bunch of regualtion from the SANS if thats what you need a quick, but I want to hear your thought on this topic.

In theory you should not need to earth the panels as there should not be fault currents that you need to get down to earth but bonding the equipment in my opinion needs to happen besides the fact that the regs insist on it.

With PV panels you are running DC and not always possible to run neg and pos together all the time which means you will get the magnetic field effect which could create eddy currents in the panel surrounds - By bonding everything together you will bring everything to the same potential and therefore avoid a possible " shocking " experience
By bonding everything you will also prevent hotspots from forming on the rails/frames due to eddy currents
It is likewise the same scenario anywhere ,where there is metal work and a possiblity of current flowing for whatever reason that the structure is bonded to ensure everything is kept at the same potential , being ground

[Isetech]

Interesting video

https://www.youtube.com/watch?v=-kjM9VWKHnk&ab_channel=PennStateSolarCenter