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.

I will let the working sparkies fill in the blanks about the last 20 years. I am retired but testing in 1 and 2 family was pretty much nonexistent. They test GFCIs with a bug eye tester but not all of them and not all the time. Our GFCIs are per branch circuit, set as 5ma and not one across the whole service like I saw in New Zealand. As often as not the GFCI is built into a receptacle in the area served (bathroom, kitchen garage etc). They do have the ability to protect down stream devices if connected properly.
Inspection is really a visual thing for the most part. Since we use a center tapped 120/240v transformer, hooking things up wrong is harder to do and easy to spot visually. Building grounding is really just assumed to be OK if one of the accepted grounding electrodes is present and properly connected. I have seen ground testing but these were commercial jobs with multiple electrodes an an array. (notably, toll booths out in the boonies and radio towers). It was mostly for lightning protection.
In 1 and 2 family the concrete encased electrode has become the standard and inspected as part of the footer inspection. Rods are inferior electrodes and water pipes are plastic.
The only debate seems to be whether a rebar turned up inside a block core is a valid connection to the footer steel.

I was under the impression that EFLI testing is only required to ensure earth-fault protection where no RCD is present. At least that's the case in Germany and Austria. Short-circuit protection is only indirectly governed by the rules on voltage drop, in theory a short circuit could persist until the thermal section of the MCB trips if the circuit impedance is high enough. EFLI stands for earth fault loop impedance, which suggests that at least in the UK it's also about earth faults rather than L-N or L-L short circuits.

I'm not qualified for testing and inspection, so I don't need to know this by heart but off the top of my head I think the required tests for any type of installation in Germany and Austria are:
- insulation resistance at 500 V DC
- continuity of earth and bonding conductors throughout the installation (measured using an Ohm meter between the earth bus bar and each connection point with an appropriately long lead)
- impedance of any earth electrodes

- RCD trip time
- RCD trip current
- where no RCD is present, EFLI and PFC (prospective fault current, calculated from nominal voltage and EFLI)
- live switching (making sure no single pole switches or MCBs break neutral conductors)
- phase rotation of 3-phase circuits

My original question was: "Here in Norway it is strictly forbidden to put up a grounded outlet without proper grounding, but if I remember right; the US NEC will not forbid to put up a grounded outlet without a ground wire if you have a GFCI.

Any body who know anything about this, or at least has any ideas?"

Maybe I should have asked. Are we so well protected by a GFCI/RCD that it would be safe to just use the 2 wires for the current needed. Not in hence to regulations, but in hence to get thing working without risking your life.

If I have a freezer and a refrigerator connected with only 2 wires and one has a faulty N going to whats usual ground and the other has similar error on L it would be extremely dangerous to touch them at the same time, so that is not the question, but if a house has bad or no grounding and al ground prongs on each circuit is connected with a wire, but not to real ground. How dangerous will it be?

It is true that the NEC does allow grounding type receptacle to replace non grounding types with no ground present if you have GFCI protection The receptacle needs to be labeled. Since most small appliances, lamps etc are mot grounded in the first place, danger is limited.
Bear in mind surge protection and those grounded appliances are missing that protection with an ungrounded receptacle.
In places where floods and storms are an issue, those old houses are being torn down tho by government and insurance company decree. The insurance can easily top $10,000 a year for a preFIRM (Prior to government flood map) house in a coastal or other flood prone area.
FEMA (the Federal Emergency Management Administration) is going through these areas with a very sharp pencil over the past few years and enforcing this. About 25% of the older homes around me are abandoned or already torn down. You are not allowed to spend more than 50% of the appraised value of the habitable parts of the building alone on improvements or repairs. That limitation leaves a lot of homeowners with little choice.