ECN Forum Forums General Topics of the Trade Non-US Electrical Systems & Trades Do we need grounding?

I like to learn about things that may be better (or worse) in other areas. Sometimes we are a little slow about updating the standards, and yes it is just as an hobbyist, but earlier I had to know becaouse we worked with companies in other countries, It was quite a job to read NEC and spot what was important to be OK in both countries.

It is not easy to be a certicated electrician here in Norway and non electrcians ar not alowed to do much here.

Is it any important differences between NZ and Australia?

About the only thing on your list that gets tested is the GFCIs in residential. Most inspectors carry a bug eye tester with GFCI testing capability.
I had an Ecos tester that checked ground impedance.
Ground/earth testing is usually done by an engineering firm but I have only seen it on some state jobs. Toll booths were one. Out in the boonies, a toll plaza is the most attractive lightning target. The grounding system is right up there with radio towers, another interesting job.
Some commercial jobs do get megger testing but not residential..

Hey dsk,
First off, I must apologise for the tone of my reply to you above, that is not fair upon you.

Australia and New Zealand actually share the same Wiring Rules, called AS/NZS 3000,
now this was bought in a few years ago, but it is due for a total revamp, since this legislation was bought out (the last amendment was on 2009?), a LOT has changed, with respect to EV charging, Solar installations, cable installation methods, voltage drop and maximum demand calculations.

A lot of this is tied to the fact that a given installation doesn't draw the same amount of current during its normal operation as it did when the Rules were first implemented (2003), for instance, lighting loads are now significantly less (with LED lighting being installed as standard), heating and cooking appliances are now more efficient and houses to a degree are better thermally insulated, saving quite a bit of heat loss during Winter.

However, with the increase of LED lighting, there has been issues with RCD's in installations where they will trip if there is pulsating DC current super-imposed over the normal AC waveform, hence we are only allowed to install Type A RCD's in any new installation, whereas, type AC (non-pulsating DC) devices caused a whole heap of issues.

Another thing that has caused issues here is the retro-fitting of EV Chargers into older houses where the Mains to the house is not large enough, if a smaller house out in the country only has say, a 10mm² Mains cable (which would normally be 16mm²), the chances of the circuit protection operating at night when the vehicle is charging, is very real.
If customers don't do their "homework" before they buy an electric vehicle, especially out in the country, the cost of upgrading the Mains and the switchboard can often be many more times the cost of the vehicle.

Hey Greg,
That really strikes me as strange and don't get me wrong I'm not having a "go" at American electrical practices.
In a country that if something goes wrong, you can have every lawyer in town turn up and apportion blame (this is only my assumption looking in through the window), it seems crazy that something like basic electrical testing is not carried out.
And to be fair, it is not hard to do at all.
We work on this over here and this is an industry-standard testing regime:

• Earth Continuity - This makes sure that there is an Earth Electrode into the ground and what resistance it has.
• Insulation Resistance - This is done with all cables coming into the switchboard, between all conductors and Earth.
• Polarity Test - Make sure that the Main Phase and Neutral conductors are not transposed.

All of the above tests are done with no power supplied to the installation.

When supply is attained, the following tests are carried out:

• Earth Fault Loop Impedance - This is done so that the integrity of the Circuit Protection Devices will disconnect a faulty circuit within 0.4s, this is a test from the most distant socket-outlet in the installation from the switchboard, through the wiring of the Installation, back to the supply transformer and back to the point of test, there are charts that will tell you if this passes or fails based upon the type of circuit protection used, the size of cable used in that circuit.
  If the available fault current is too low to operate the fuse or CB on that circuit will not operate causing a potential fire due to heating of the conductors in that cable, setting the insulation on fire.
• Operation of RCD's - GFCI's may be different, over here an RCD must trip within 300mS with a maximum trip current of 30mA ( there are different RCD's for medical areas, but that is outside the scope of this).

The worst thing that we strike over here is that the Liney from the PoCo, has hooked up the mains coming into the house or whatever, backwards, they are meant to test this, it is Liney 101, otherwise when the installation is livened, there is either a very loud bang and some flames or all of the exposed metalwork (like faucets (taps) have full mains voltage on them, which is not great if you're looking to have a shower in your new house.