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Posted By Topic: Earthing requirements for generator supply

gofishing
Jun 19 2016 17:08

I have been asked to connect a 5kw generator to a remote holiday cottage with no mains supply (had power but supply disconnected due to rotten/chewed cabling).
What earthing requirements are needed in this situation? Do I need to install an earth stake or do generators have an internal earth connection that will suffice? Not had cause to use a generator before now so no experience with them.

I will be running new cabling for 3-4 lights and probably 2 power points that can be used when the generator is running. The most convenient place to mount a new DB will be on the original switchboard/meter panel but there will be no connection to any original/existing wiring - this will eventually be stripped out. The owners will also be utilising solar panels to charge small items which will be totally independent of generator power. Cooking and water heating will be done via gas/wood fire so it\'s a very basic set-up intended for occasional occupation.

The new DB will be supplied via a 16a lead to the generator.

Any advice would be greatly appreciated.

   

pluto
Jun 19 2016 17:28

Figure 7.6 of AS/NZS 3000 gives a circuit of how to do it.
   

markcraven
Jun 20 2016 07:19

Would also be useful to look at AS/NZS3001 as it might be classed as a connectable.
   

markcraven
Jun 20 2016 07:35

Just re read post not transportable so only AS/NZS000 applies.
   

gofishing
Jun 21 2016 21:15

Thanks, looks like a straightforward solution. Will see how they have coped with running extensions leads after a few weekends up there, but thinking the simplicity of fixed wiring will make life much easier. Just need to think of every possibility before I head out next month!! Long way to head back to the nearest wholesaler!!
   

AlecK
Jun 22 2016 08:28

Check the generator output, many small gensets are centre-tapped winding ie not really a 230 V single phase generator but a 2-phase 110 V 180 deg generator.

With one of those, the N-E link in the installation will short one winding.

they\'ll need a genset with an isolated winding; ie NO connection between winding and frame (separation equivalent to an isolating transformer)
   

mf51to1
Feb 04 2020 15:07

You say look at figure 7.6 however that diagram is “connected to an installation with a mains supply”.

The set up in the opening post is that it’s connected to a DB (not MsB) with no normal supply. Does the DB need to be upgraded to earth electrode and MEN link in that case?

   

pluto
Feb 04 2020 15:51

Another option Appendix C of as/nzs 3010 it can use any single-phase generator.

It can be loosely described as built-in extension cords but need double pole switched socket outlets.
   

AlecK
Feb 04 2020 17:11

As of the date of the OP (2016) Fig 7.6 can only have referred to 2007 +A1+A2. which is still the cited version
the title of the Fig is "...connection of a standalone system ..."; and there's NO other supply.

Note that ESR 60 requires compliance with AS/NZS 4509.1 for a standalone supply installed to Part 2.
and yes, that does mean an earth electrode 9installation of which is high-risk PEW); even though in most cases the only real function of an electrode is to stop the building blowing away.

Since 2005 edition of 3010 doesn't have any appendices, I believe pluto's reference to App C of 3010 must be to 2017 edition. That system is not currently permitted by ESRs - so (sadly) it isn't a compliant option. And since the next amendment of ESRs is only going to update citations in Schedules, and not change any actual regulations; it'll be the one after before ESR 60 stops citing "4509.1"; or allows use of the system in App C of 3010:2017 by some other means.



Also the 2017 edition includes a number of errors; the correction amendment is almost published. Most are minor, and I would need to check whether any of them affect standalone systems; but it would be unwise to rely on it.
   

mf51to1
Feb 06 2020 22:25

You are correct - Thanks AlecK.