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Thread: No earthing required?

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    No earthing required?

    Hi Guys
    I recently went to a client's house to quote on renovations .
    Click image for larger version. 

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    Pls see pic attached. Not sure if it has uploaded correctly.
    I found the earth wire connected to a galvanised pipe, (seen this many times before), but the galvanised pipe has corroded right off.
    This guy had already bought the house and gotten a certificate of compliance.

    I told the owner that surely they should have knocked in a spike or two at least and tested for good earth resistance.

    The owner contacted the electrician and the electrician said that an earth is not required. (P.S I am a qualified electrician with wiremans).
    Are there instances where this is the case? I know on the compliance certificate it says: "Earth resistance if required", so I'm wondering if I will learn something new today

    Perhaps if the supply is in a certain configuration it is ok?
    I know the transformer neutral makes the installation safe most of the time anyway but still feel there should always be adequate earthing nonetheless.

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    Diamond Member AndyD's Avatar
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    Is that earth wire still connected? If it is it's in breach of the CoC;
    7 Connection of conductors and earthing and bonding are mechanically sound and electrically continuous
    Difficult to say if an earth electrode is required without more info.
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    Thanks Andy

    I spoke to the electrician who issued the C.O.C and he informed me that he recently had the refresher course for the latest 2017 Sans edition.
    I have been slack and not yet bought it but now realize I need to buy the new addition asap.

    There were a few questions I had regarding the certificate he issued:

    1. No earth electrode resistance test done and of course the fact that there was no earth spike at all.
    It is a TN-C-S supply as usual in these parts.
    His reply was that the regulations state that for existing installations the "secondary earthing mat/spike" on the clients property is not compulsory on a TN-C-S supply.
    The certificate is also passed under the "for an installation existing before this publication of sans10142"

    2.There were no insulation resistance tests done
    This he informed me was also not required for an existing installation.

    3. section 4 no. 15 "Is the position of a readily accessible earthing terminal..."
    This he had indicated "YES" but there was definitely none installed.
    He informed me that this was no longer necessary as per new regulations

    4. Lastly at the WC1 box there was 2 orange toggle circuit breakers (d curve), 50amp and 30amp. With a seoerate prepaid meter in the flatlet and main home.
    He had signed the flatlet off as a sub DB instead of having 2 separate certificates which he agreed is how it should have been done, but I would like to know if we are correct in that assumption in your opinion?

    I am not out to roast this guy or anyone else, I just need clarity if possible as i myself sign off homes and try not to bring unnecessary expense to the client although I prefer to be cautious.
    I know I am a bad guy for not yet getting the new addition of sans 10142 but will asap and plan to do a refresher course too as i feel i should know all this already
    Thanks for your time, it is greatly appreciated

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    Diamond Member AndyD's Avatar
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    Similar to yourself I don't have edition 2 of the regs yet so some things may have been changed. I'm also not the best person to give opinions on domestic certification because I never do domestic work of any kind.

    Quote Originally Posted by hartdev@hotmail.com View Post
    1. No earth electrode resistance test done and of course the fact that there was no earth spike at all.
    It is a TN-C-S supply as usual in these parts.
    His reply was that the regulations state that for existing installations the "secondary earthing mat/spike" on the clients property is not compulsory on a TN-C-S supply.
    The certificate is also passed under the "for an installation existing before this publication of sans10142"
    Yeah, from the photo he obviously didn't do an Ra test on the earth electrode but, regardless if the regs state it's required, if it was installed and if it's still connected then it should be part of the CoC. The regs state the absolute minimum requirement but sometimes a higher standard may be required, especially when it comes to earthing arrangements. Is it plain TN C S or is it PME or PNB? Effectiveness of earthing is highly prone to seasonal changes and it may have also been the opinion of a previous electrician that a local earth rod was required for some reason, hence my stance that if it's there it should be fully functional and subject to testing and inspection during certification.

    Removing or ignoring deteriorating earth electrodes is extremely bad practice IMHO and I wouldn't be taking blase statements about 'not compulsory' or 'before publication of regs' as an excuse. If it was installed at one time then it has to be considered that there was a good reason and I think the onus to prove it's no longer required would then fall on anyone who removes it or fails to maintain it or claims it's unnecessary. The minimum motivation I'd be satisfied with is full earth impedance tests and earth fault disconnect times calculation to prove adequacy of existing earthing, also confirmation there's no special location or medical location requirements, also confirmation there's no alternative supply requirements (generator/UPS etc) and a risk assessment taking consideration of likely seasonal ground conductivity changes and local lightning requirements. Customer requirements could also play a part ie effective operation of surge arrestors for protection of IT equipment etc if they're installed.

    Quote Originally Posted by hartdev@hotmail.com View Post
    2.There were no insulation resistance tests done
    This he informed me was also not required for an existing installation.
    The property changed hands so a full CoC was required. To my knowledge insulation tests should have been included...
    Code:
    6.6.1.22 The insulation-resistance test on wiring and components shall
    be performed in accordance with 8.7.8.
    Code:
    8.7.8.2 The insulation resistance, measured as follows, shall be at least
    1,0 MΩ:
    Amdt 8 allowed for a half assed exception but I don't see why it would apply....

    Code:
    8.7.8 
    NOTE 2 In the case of existing installations where the power may not be switched
    off from certain circuits in order to carry out this test, the fact that the circuits are
    subject to the supply voltage can be regarded as evident that the insulation
    resistance is compliant. Amdt 8
    Quote Originally Posted by hartdev@hotmail.com View Post
    3. section 4 no. 15 "Is the position of a readily accessible earthing terminal..."
    This he had indicated "YES" but there was definitely none installed.
    He informed me that this was no longer necessary as per new regulations
    Yeah, I hear edition 2 changed the requirement for the accessible earthing terminal

    Quote Originally Posted by hartdev@hotmail.com View Post
    4. Lastly at the WC1 box there was 2 orange toggle circuit breakers (d curve), 50amp and 30amp. With a seoerate prepaid meter in the flatlet and main home.
    He had signed the flatlet off as a sub DB instead of having 2 separate certificates which he agreed is how it should have been done, but I would like to know if we are correct in that assumption in your opinion?
    I'd only class the flat as a sub-DB if it was fed from the main DB. If the flat supply is completely independent from the main house DB then you have two main DB's which should have been tested as separate installations.
    Last edited by AndyD; 06-Sep-17 at 12:38 AM. Reason: decided to use code tags for quoting electrical code
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    Thanks so much for the info.
    I will update asap

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    Hi
    This is what i found in the regs :
    8.6.7.2 Where the supplier provides an earthing terminal, this test is optional.
    6.11.5 A readily accessible earthing terminal may be provided for the bonding of other services such as a telephone, an audio or a video system, and the like, to a building. Where installed, such an earthing terminal shall be bonded to the consumer's earth terminal by a conductor of at least 6 mm2 copper or equivalent, and shall be identified by the earth symbol . the old regs stated that the terminal ''SHALL'' be provided.
    8.6.8 Insulation resistance NOTE 1 Before power is connected to any new or altered circuit, the test for insulation resistance should be carried out to ensure there is no short-circuit or high impedance faults in the installation, and that it is safe to energize.

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    Thanks Hotspot.
    Are you looking at the latest March 2017 Updated Regs?
    I guess I'm not entirely sure what "supplier provides an earth terminal" entails.
    The council provides a live and neutral which is connected to the earth at the transformer but I wouldn't call it an earth terminal... what is your opinion?
    As far as 6.11.5 is concerned Andy and the other electrician I spoke to both agree that this is no longer required as per new regs.
    With regard to 8.6.8 It is an existing installation which has been signed off, so there has already been power connected to the circuits but I believe we should be testing for insulation breakdown, especially in houses that have been around for a while.
    Thanks for the reply, much appreciated
    I plan to speak with the WCAEIA today regarding this c.o.c that has been issued, my client feels quite strongly that he should not be paying for the earth spikes etc so here I am stuck in the middle lol

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    Hi Hartdev.
    yes i am using 2017 regs.
    refer to figure J.2.1 for TN-C-S system.
    Good luck i know its not nice to be in the middle of S....t hopefully it gets sorted soon

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    Eskom also conects the N to E at the TRFR and also bridge them at in the meter box. They use TN-C-S

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    Site Caretaker Dave A's Avatar
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    While 7.12 is about alternative supplies, perhaps it's worth mentioning that under 7.12.3.1.1, Note 1 is as follows:

    In a TN system earthing of electricity supply, an earth electrode is normally not required in an electrical installation.
    The trouble with opportunity is it normally comes dressed up as work.

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    hartdev@hotmail.com (10-Sep-17)

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