Good day
Can I please be assisted with past papers and memo's for paper 1.
My email is Muziwn@yahoo.com, thank you in advance
I registered paper 2 of installation rules and m asking for old question papers and memos please. My email: mokibelojunior@gmail.com
My WhatsApp 0783107811
Thanks in advance
Can someone please assist with the following?
I do have the newest standard. SANS 10142 third edition.
1. Touch voltage.
Previously it was 30 volt. Now it is 25 volt for a period of not longer than 5 minute. Refer to section 8.6.5.4 (Page 256). Everyone I come across states it must be 30 volt. I need to confirm the actual touch voltage. Shall I state on the examination paper which standard I am using to make sure that I am not getting penalized.
2. Previous examination
I am looking for the complete answer sheet for the previous examinations done during July 2021. Paper 1 and 2 please? Can someone please assist with this if possible?
3. SANS 0292.
Can someone please asist with a copy of this standard? If not possible, can someone please assist with issue 4 below? This is important. I do see they are focussing on this currently.
4. SANS 0292:
Can someone please identify the following correctly. I am getting conflicting information.
Refer to the diagrams below 8.2.1 to 8.2.4, and identify the following extension earthing supply systems and write the answers next to the question numbers:
Forgot - my email is gerhard.oosthuizen@yahoo.com
Thanks
gerhard
Referenced from SANS 10142-1 (ed 3.1)
b) suitable protection shall be installed; and
c) where, for practical reasons, the supply to the installation cannot be
automatically disconnected by an earth fault current of double the rated
current (or higher) of the main protective device, as an alternative, an earth
fault detection and disconnecting device can be installed at the point of
control of the installation. The earth fault detection and disconnecting
device shall be so installed that they operate at a current related to the
earth loop impedance which will limit prospective touch voltages under
short-circuit fault conditions to 25 V for a period not exceeding 5 s.
NOTE 1 These requirements can easily be achieved by using an earth leakage
device that has a rated earth leakage tripping current (rated residual current) IΔn not
exceeding 300 mA. Devices provided with a time delay of, for example, 0,1 s, will
ensure discrimination with earth leakage protection devices in final circuits.
NOTE 2 Separate earth fault protection could consist of sensitive earth leakage
protection, which might not always be practicable where large currents are involved.
Comments are based on opinion...not always facts....that's why people use an alias.
Thanks. Above question is confirmed.
I also have a another question. When they give any question about estimating loads of the installation they will say for example the following....
Stove supplied with 6 mm square mm with minimum ECC.
My question: What is minimum ECC? In the old days a 4 mm square was fine for a 6 mm square conductor. Most of the previous papers use ECC as 4 mm square.
As I understand the new standard, the earthing conductor will be the same size as the phase conductor.
So I understand that the earth conductor is also 6 mm square mm. Is my assumption correct?
Thanks
That's a tricky one in my opinion as a 6mm˛ FTE cable as the ECC as a 2.5mm˛....
The whole thing with the Ecc being same as phase is if it does not form part of the cable is the below, not sure if it is applicable though to that question but sure it plays a role as has length involved
2.1 Earth continuity conductors
6.12.1.1 An earth continuity conductor shall
a) consist of compatible conductors,
b) if it forms part of a cable other than a flexible cable, comply with the relevant
requirements of the standard for the cable,
c) if it forms part of a flexible cable, be of the same material as, and have a
nominal cross-sectional area at least equal to, that of the largest phase
conductor,
d) be able to carry the prospective fault current without excessive temperature
rise of the conducor, within the disconnecting time
e) if it does not form part of a cable or flexible cable, have a nominal cross-
sectional area at least equal to that determined in accordance with table 6.28
More so indent e) and the table on page 167.
But that has more to so with length as well the table...
Sent from my SM-N960F using Tapatalk
It still confuses me. The length of the ECC will play a significant role in selecting the minimum ECC size.
I am going to use the same conductor size for the ECC than of the live conductor size.
The length of the ECC is critical. Therefore the minimum ECC size cannot be determined.
If the length was known than one can use the following formulae to calculate the minimum ECC size.
Touch voltage = 2 x I (Breaker Size) x R (ECC resistance)
R = (rho x l) / A
From above the area of the ECC can be calculated.
Even in this formulae, length is needed.
Is there anyone with a different idea. I tried to google it but not much is available.
Hi Gerhard.
Use table 6.28(a) of the SANS 10142-1 Ed3. That will help you with the ECC size if its the same size as the PH conductors. Watch this video from our training modules for WIREMANS LICENSE. Hope it helps https://www.facebook.com/TDMITrainin...71562097739711
Dylboy (01-Feb-22)
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