7.12 Alternative supplies

[ians]

Just to spoil your day if you also recently decided to buy the ed 3 ... what a waste of money... time to share this with other to try recoup some of the money ... anyone know how to down load PDF and cut off the top part and scrap the all red tape?

https://store.sabs.co.za/sans-10142-1-2021-ed-3-01.html

[ians]

The alternator and petrol motor are normally fastened to the frame of a portable set with a rubber vibration pad as per attached pic

Attachment 8412

I never thought of those as a means of isolations from the frame or ground.

I went and had a look at my generator and did a few continuity tests.

The tank is isolated from the frame.

the flex conduit between the alternator and socket is PVC ...

Then I thought surely the socket outlet has an earth from the alternator which is also mounted on the outer metal frame ... no continuity ... it seems the earth from the alternator is also isolated from the metal frame ... using a plastic socket outlet.

Thanks for the lesson ... this is what I love about this forum ... no matter how much you think you know ... there is always something to learn and you might see something or do something in a manner which you think is right ... but you might have been doing it wrong or just not seen it from another angle.

What we can learn from this ... never earth the socket to the frame of the generator on a VOV construction site generator.

Which now has me thinking about the other generators which We have connected to premises ... if the generator is not a VOV then how as these unit make safe and what happens if you bond the earth to the frame?

[Dylboy]

Basically ,only the supplier may earth the neutral - You can become the supplier on the load side of a generator or inverter .

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.

You will see that this is also stipulated in municipal bylaws and Eskom bylaws since the day dot.

The reason behind the reg is to prevent fires and I will take an extreme case as an example.

My house is fed from the municipal cable network and I take 80 Amp single phase supply.The neutral is earthed at the substation transformer, 800KVA
If I then install an inverter and bridge my inverter neutral to earth with a 6sqmm or 4sqmm wire as the inverter is only 1KVA, and that inverter neutral is direct connection to municipal neutral.

If for some reason the municipal earthed/neutral comes loose or is stolen my house neutral/earth now becomes the earth/neutral for the 800KVA transformer and all imbalanced load will flow through my 16sqmm mains cable and then through my 4sqmm neutral to my inverter which is earthed
That 4sqmm wire could be in my roof space , overheat due to the current flow and cause a fire .
That earth neutral current flow could be as high as 200Amp on an imbalanced load.

That is the though process for that particular regulation

That makes all the sense! Thank you for taking the time to explain! I should have thought of the PEN fault. I really appreciate it !

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[Dylboy]

I would say No! Consult the battery or inverter manufacturer.
The Neutral of the AC side of the inverter is derived from the battery from a bridge type electronics, so in effect, the negative side of the battery and PV panels are effectively connected to the Neutral of the AC out via a Diode/FET.

Joining this to earth would damage the inverter.

To add a little bit more here. Whilst the Neutral is connected to the negative of the PV panels and battery, it is not a permanent connection, but rather a high speed switching, in which the Neutral of the AC output is effectively alternated On/Off between the battery/PV positive and negative terminals.
Only in the case that the battery/PV are isolated from the AC output may the DC negative side be earthed. However I doubt that they are isolated, as this would increase the cost and physical size of the inverter by introducing an isolating transformer.

Very very interesting! Thank you ! so much to learn and technical items to learn. We do follow manufactures but I like to know why things are done in a certain way. Some of the older gents I talk to don't know as its new technology to them too. Really appreciate your reply, thank you !

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[Dylboy]

Ok so I phoned a friend ... now I am pissed off because a I stalled purchasing ed 3 ... edition 3.1 was launched 2 weeks ago and by the way apparently there are many changes in the new edition and it still doesnt include the other draft that is still in draft ...

I also need to get the NRS 097 code to understand solar installations.

I enquired about the functional earth and that kind of stuff and as usual ... its never just as simple as we think

That other draft that you shared is one of the books I can not wait to be sorted as it has a lot of information and is so useful.

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[ians]

It might be a good idea to read this document if you planning to do a solar install

https://www.sseg.org.za/wp-content/u...2020-07-20.pdf

[Derlyn]

The alternator and petrol motor are normally fastened to the frame of a portable set with a rubber vibration pad as per attached pic

Attachment 8412

Bottom right on control panel of this portable genny is an earth stud.

What is the use thereof ? When should it be used ?

Derek

[Dylboy]

Only guess is if the output N is then externally bonded to E that then the same E is bonded to the frame for equipotential bonding

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[ians]

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.
7.12.1 General
7.12.1.1 Subclause 7.12 applies to an installation that incorporates
alternative supplies intended to supply, either continuously or occasionally, all
or part of the installation with the following supply arrangements:
a) supply to an installation or part of an installation which is not connected to
the main supply of a supplier;
b) supply to an installation or part of an installation as an alternative to the
main supply of a supplier; and
c) appropriate combinations of the above.
NOTE 1 Requirements of the supplier should be ascertained before any alternate
supply is installed in an installation connected to the main supply of a supplier.
NOTE 2 This part of SANS 10142 does not cover the generation plant, integration and
synchronising requirements of an alternative supply operating in parallel with the main
supply to an installation.


Grid tied or Hybrid inverter and solar systems.

The item covered in red ... something which I have noticed people are turning a blind eye ... they are aware of the consequences of the installation and the type of meter installed.

The question is going to be who will be held liable for the penalties and or investigation into the usage ... will the inspector who signed the COC be responsible or the owner using the electricity. How would they calculate the estimated usage ... will they fine you will you be liable from the date on the COC ? I dont think people signing COC's understand the implications of signing the COC.

People it is not that difficult to work out how much power you are pushing back into the grid ... especially if you have a remote monitoring system.

2 thing you gonna need to be aware of ... the date on the COC or invoice date for the installation and remote viewing data.

[Dylboy]

Morning

So if we add a generator, change over switch and all that, do we still need to contact the supplier ?

My view is that as there is a change over there is no backfeeding thus no need to contstc supplier.

Keen to find out more in this.

Also what i need to find more on but may do annew thread is with PV installs and registration of them and then if not used to backfeed at all then must it still be registred.

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