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Posted By Topic: Submain Earth Conductor size

Aug 03 2015 19:39

Hi All - Simple question but cant quite convince myself of the answer
A Submain to garage 4mm T&E which has 2,5 earth - Table 5.1 details these sizes all OK but is this OK for a distribution earth
I understand it will need to meet loop resistance etc as standard details but in the good old days with a 4mm - 6mm there would have been same size earth conductor
If someone could point me to the correct part of the standard that would be appreciated if its somewhere else than the table and notes associated with 5.1

Aug 03 2015 19:58

table 5.1 is all you need for this

Aug 03 2015 20:02

Thanks AlecK I though it was but wasn\'t convinced - Appreciate your wisdom

Jul 16 2018 11:38

Just going to dredge up an old post... I do believe that in the context of a submain there is a minimum requirement of 6mm2 for a submain earth, meaning that running a 6mm2 2C+E with an integrated 2.5mm PEC is not compliant. Problem is that this info is included in AS/NZS 3018 which has just been withdrawn... not sure where to go. Do any of you have this standard which I believe sets out minimum earth requirements. My copy which I just found as a PDF is corrupt and doesn\'t want to open. I don\'t mind buying the standard again, except that if it is no longer relevant then no point referencing it. So my next question - where has it gone?
Just doing an inspection and have pinged a job, but now can\'t find reference for correct info.

Jul 16 2018 13:43

There\'s no minimum of 6mm2 for a submain earth. We\'ve moved on from prescriptive regulations these days.

Yes 3018 is no longer required.

3000, 3017 and 3008 should cover you in most cases.

Jul 16 2018 13:48

Thanks Doug, I had no knowledge that 3018 had gone. It is only when I went to open my corrupted PDF of 3018, then went to Standards to download, that I realised this. I wonder how many other Standards have gone that I\'m not aware of.
I really liked 3018. I thought it was a good standard! RIP 3018 :(
....going away to eat some words...

Jul 16 2018 14:29

There is ONE important point about AS/NZS 3018 it was intended to cover domestic installations only and in a simplier way (less complex) than would be given in AS/NZS 3000. i was one of the AS/NZS 3018 drefting team a good number of years ago.

To this end there was some parts that had more generous provisioning in some areas to give a slight increase in electrical safety when this could be done at very little extra cost in materials and the labour costs being approximately the same.

The same arrangements also applied for the NZ ECP51.