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Posted By Topic: Stand-alone generator earthing

Dufresne
Oct 11 2018 18:24

I’ve been grappling with the application of AS/NZS 3010 to generator earthing in a situation where a permanently-connected, stand-alone generator supplies power to an installation. Clause 2.5 of AS/NZS 3010 says that “When the multiple earth neutral system (MEN) is to be employed … the MEN connection shall be made at the main switchboard. This will require disconnection or removal of the alternator winding neutral to frame links within the generating set where that generating set switchboard is not nominated as the main switchboard”.

Through inference, the wording appears to say that “where the generator switchboard IS nominated as the main switchboard, the generator neutral to frame link is allowed to remain in place as the MEN connection”. If that interpretation is valid then we can nominate the generator’s switchboard to be the main switchboard and keep the neutral-frame link in place.

Any advice or views regarding that understanding would be appreciated.

   

Sarmajor
Oct 11 2018 19:10

If you decide that the Generator is the main switchboard and has the MEN link then it must comply with all the rules that apply to the MEN link.
Size, removeable for testing and colour of insulation if insulated etc...

Also the generator switchboard will have to comply with all the rules around being a switchboard.

It might just be easier to remove the link from the Neutral / Star point to the frame.
The generator frame will still require an earth connection to the Main earth bar of the installation that it supplies.
   

pluto
Oct 13 2018 18:04

use AS/NZS 3000:2007 +A1+A2 figures 7.4 if generating set is plug and socket connected, and figure 7.6 if connected btÿ installation wiring.

Do NOT use AS/NZS 3010:2017 as it is NOT cited for use in NZ at the moment and it also contains some errors in the text and figures, in particuklar for figures marked for use \"in Australia only\".
   

mrsparky
Oct 15 2018 07:46

Pluto, if connected using fig 7.6 does this require electrical inspection for the main earth?
   

Dufresne
Oct 15 2018 09:28

Thank you for your advice Sarmajor
   

pluto
Oct 15 2018 12:23

Electricity Act 1992
Defines an electrical installation as follows
Quote starts

Electrical Installation

(a) means all fittings
(i) that form part of a system for conveying electricity;
and
(ii) that form part of such a system at any point from the point of supply to a consumer to any point from which electricity conveyed through that system may be consumed; and

(b) includes any fittings that are used, or designed or intended for use, by any person, in or in connection with the generation of electricity for that person’s use and not for supply to any other person; but

(c) does not include any electrical appliance

Electrical wiring work means prescribed electrical work that consists of any of the following work:
(a) the installation or maintenance of electrical wiring:
(b) The connection or disconnection of fittings to or from electrical wiring

Quote ends

A standalone power system working at 230 volts is covered by “Electrical Installations clause (b)” and also classified as PEW which covers the person permitted to carry out the work.

This also includes the issue of a CoC and all the other certifications required by ESR 2010.

   

AlecK
Oct 15 2018 17:30

\" if connected using fig 7.6 does this require electrical inspection for the main earth? \"

Yes.

A standalone system has no \"mains\"; but it still has a \"main earthing system\"; and the definition of \"mains work\" (which is classed as high risk PEW unless it is low risk) includes any work on a \"main earthing system\".