Hello and thanks for the messages of welcome
I will attempt to participate if im able, My level of knowledge is broadening slowly. We would appear to do somethings a little differently (way) down here.. in Kiwiland

Cheers
The oldest apprentice in NZ

Appy;
Jump on in and tell us a little about how an electrician does things on your end of the world

old appy,

Welcome!

We're always looking for some fresh viewpoints and find it interesting to hear of how things work in other areas of the Globe. I was just looking at a website about New Zealand tourism and it seems like a pretty unique place! I Look forward to your participation.

Bill

Old Appy: I like your title. Must be an interesting reason behind this choice.
I noticed the water rotates in an opposite direction, when flushing toilets, in your country. I was impressed by the amount of stainless steel used for sanitary facilities.
I purchased some of your NM cable, for use at the South Pole. Using the black conductor as a grounded/neutral took a bit of adjusting. The absence of a white conductor was my first discovery.
I also noticed your standard switching position is opposite to the US application. Up is off, and down is on, unless the ones I observed were incorrectly installed.
I won't go into my experience with driving on the left side of the roadways.
I was impressed by the lack of poverty, among the citizens, and the low crime rate.
The Police, being unarmed, was a good statement, regarding the crime situation, and culture.

Our water still flushes the opposite way, our Police dont carry side arms yet, thankfully. We use Black or Blue for Neutral only, and are no longer allowed to use these as a switch wires either or Green and Yellow/Green (earth only)lots of changes industry wise here to bring us in line with other countries in the South Pacific ie Aus.
Also our lights switch down for on up for off, well at least mine do. We typically use a 230 volt 1 phase supply in town, some houses in the country may have 2 x phases or even 3. as do many or most factories, I will try and keep up with you guys but if i ask the odd dumb Q? please bear with me

Old Appy: Unless you are going to ask "what color is the green grounding screw?" we all appear to agree, there is no dumb question. This trade, being a theoretical technology, presents a lot of unknown facts.
I have 50 years of involvement, I feel I am just beginning to understand some of the basics, that I should have learned years ago.
I was too busy working to learn anything.
Do the Kiwi's call an apprentice "an off sider", or is that the Australian term?
I did examine some of the distribution and power systems in your country. The economical consideration was impressive. The US is a "throw away society", compared to New Zealand's concept of using everything forever.
The reuse of containers, repairing and restoring equipment, was the practice, in this country over 50 years ago. It is gone now, but may have violent repercussions, in the future.

Even "what color is the green grounding screw?" isn't a dumb question... Eagle brand ground screws are almost blue, sort of a teal I guess. So... in this context, the answer would be "for Eagle brand, bluish-green or teal".

Old Appy:
Welcome to the group! Great to see more people joining in.
As everyone already stated, feel free to ask any questions you have. No questions are ever stupid, however I hold the record for stupid answers!

Got a question to throw your way conserning your power system.

As you stated, the Residential service is 230 VAC 1 phase [is this 50 or 60 Hz??].
I am also going to assume that the secondary is grounded [if not let me know] and that the system is 1 phase 2 wire, rather than our 1 phase 3 wire systems.

Do you have a grounded conductor, or just a center tap ground at the transformer. And if the center tap is grounded, is that brought to each main service panel via a conductor ran with the service feeders, then bonded to the service and grounded at each service, but is not used in any power circuits??

Think I may have asked Bennie about this in a forum a while back, but we ended up discussing something else - "now for something completely different" - which eventually led to me forgetting all about that certain point.

Anyhow, reply if you want to.
Will be great to swap trade stuff with someone outside North America [more like not even on the American Continents, or even in the Northern Hemisphere!].

Your Summer season is coming to an end now isn't it? Ends at the Equinox [March 22].
Love that simple but completely necessary part of Earth / Nature! We're finally getting away from the rain, cold and miserable weather of Winter, heading into Spring, and the sun is out past 6:00 PM !
Hurry Summer Solstice!!


Scott SET

Scott: Sorry I missed your inquiry, on the other discussion. I will let The old apprentice, address this subject. It will be good for his training.
I can maybe add some to his response after his posting. I learned a lot when I was there. The old "postman holiday scenario". Visiting one of the best vacation spots in the world, and studying their electrical systems.? How sick can I get!

Well i will try to answer your questions and if i'm wrong i hope the more knowledgable among you will put me right.
From the transformers on the roadside we have a 3 phase,400 volts (between phases) or 230 volts phase-neutral phase-earth most households would use single phase.We utlilise a multiple earth neutral (MEN) system of distribution the transformers are in a star configuration (i think) with Neutral centre tapped and Grounded (how am i doing Bennie?)
the household would have a earthing electrode driven into the the surrounding ground for fault current so from the transformer 2 cores are used phase and neutral usually a 16-25 mm neutral screen conductor direct buried. In a 3 phase system the neutral carries only the out of balance current.All at 50Hz.
Something of interest our Country is made of 2 islands ( north and south) the majority of the people live in the north, the majority of the power comes from the South, they transmit the power across the water between the islands in HVDC to get around any out of frequency problems.
Nearly forgot our power is generated at 11kV stepped up to 220kV or 110kV for transmission to the Network subs from them down to 33kV and 11kV and then 400v and 2
Alas yes summer comes to an end it has however been glorious and a cool spell is welcome.
TTFN

[This message has been edited by old Appy (edited 03-21-2001).]

Old Appy: Scott is a detailed person, I am sure you have impressed him, you are at the top of your class.
I wanted to see your style of technical writing. It is exactly as I anticipated.
I have always been impressed with the style of expression, used by the residents of the UK, New Zealand, and Australia. They are direct, to the point, and do not use a lot of flourish, to make a statement. I wish I had that literary, and verbal, ability.
Words and statements are usually self explaining, making them easy to understand.
My study of the systems, in your country, indicated a very logical application of technology. I was not aware of the DC transmission line, from the South Island. This is very interesting. I know there is a lot of water on the South Island, I understand there is a lot of hydro plants.
We have a 500 KV, DC line from Oregon to California. It is in sync with the power grid, where supplied, and converted, at each end. I can understand why sync is not necessary in your application.
The cost saving, of the distribution system you have, has a lot of positive qualities.
One transformer bank can supply most domestic and commercial loads. You do not have the loss of neutral problem, inherit in our system.
Voltage drop tolerances, copper consumption, and physical sizes of conductors, are reduced by your technology.
I would like to get a copy of the ampacity ratings of your various wire sizes. I had a chart, but have lost it. Someday we will use metric sizes, it is a very good system.

To add more, concerning my examination of the electrical systems;
I researched statistics concerning the risk difference in using 230 volts to ground, verses 120 volts. I was surprised to see a decrease. I think Old Appy can confirm this fact.
I investigated the cause, and came to the following conclusion;
The countries using 230 volts as the minimum, stress isolation, and insulation, and discourage indiscriminate grounding where not necessary. Essentially they reduce the third lethal path. GFCI requirements are not prevalant. Most wall outlets are switched. What a sensible approach to child proofing.
These countries deal with the cause of a problem, we tend to address the effects, and the problem is not prevented, or corrected.
Now you know how my brain got damaged.

guys;
i'm getting the feeling that we're the only country around on 120V ?



is that true?

Sparky: There is a website somewhere that has the common voltage and frequency of every country in the world. I will try to find it. Anyone out there who knows please jump in. It may be a tourist travel site.
I think you are right, about 120 volts. Most of the American continent, Hawaii, Alaska, and possessions of the US like American Samoa.
British Samoa has 240/415, 50 hertz. I once tried to modify generators to sync with their system. It failed miserably.

We do take extra care ensuring all metalwork in a house or factory is Bonded correctly and grounded to allow a very high fault current path and the opperation of overcurrent protection devices, also circuit breakers are correctly rated for PSCC (you may call it Maximum Fault Current i think

This is another area of interest to me. 230 volts faulting to a grounded object having a fixed resistance will cause a trip more effectively than 120 volts.
Appy, do you still use fuse wire, with different current ratings?
I noticed a lot of copper roofs on houses, is there any special procedures concerning these? Do you have many lightning strikes?
I was there in November, both times I visited. I did not review the weather and climatic conditions.

Not many copper roofs around now days -to expensive. Alot of corrogated iron its not a requirement that i know of to bond a metal roof in a house Althought a person recntly died reaching to the metal roof from a metal swing set to retrieve a tennis ball, the roof had some alterations and a phase conductor had been pierced by a roof nail (live roof) then into a wooden truss with pvc spouting there was no fault current path until the unfortunate incident, Not so much lightning, seem to remember more 20 years ago, alot of rain !!
And we no longer use the porclean fusewire holder (coarse) type of protection many houses still have them, as i do on some circuits, if you add to a circuit that has one of these you must upgrade the circuit breaker We have retro MCB's that fit into the holders. Much Better

Bennie,

There's quite a few Websites with World Power Statistics. Here's a couple:
http://kropla.com/electric2.htm
http://www.clary.com/Service/IntVoltage.asp

Bill

nice links Bill.

the first one will show plugs/receptacles. i wonder if they argue which way is up like we here do??

Appy: I am glad the space station missed your country.
My reference to copper roofs could have been only my assumption. I noticed a lot of green colored roofs. I once flew over The Netherlands and noticed this same thing. I was informed they were copper, that due to weather exposure, were green from oxide formation.
The concept, I noticed while in your country, of not wasting natural resources, maintaining, and protecting equipment was very educational.
I saw a 1931 Ford, Model A pickup, in mint condition, parked in the street in Christchurch. The bed contained sheep shearing tools, it was still being used as a work vehicle. I insulted the owner by saying " beautiful job of restoring", he was irritated and replied "not restored, it has always been in the same condition".
This is not an electrical related message, but may set the stage for explaining some of the reasons for different technology.

[This message has been edited by Bennie R. Palmer (edited 03-23-2001).]

Appy,

Thanks for the info!

From the Voltages you described, it appears that the secondary distribution systems are 4 wire Wye's [AKA 4 wire Star].
Also looks like the common conductor is used for a dual voltage system [230Y/400 3 phase 4 wire]. It seems to be bonded to Earth much the same way we do it here.

One thing came up while looking over this type of system is the problems related to arcing ground faults that are inherent with 4 wire Wye systems above 150 VAC to ground. In the US, it becomes a matter when the service's rating is 1000 amps, or more.
The use of Ground Fault Protecting type main breakers [or similar type of main disconnect] is done here. Ground fault limits are very high, as compared to the limits for personnel protection, plus they only monitor Line-to Ground faults, no overcurrent protection is done with these [except that of the main protecting device].
I'll keep the Techno Babble junk low here, but if you are curious about this, let me know.

Don't know if and where this might be used in your situations, so feel free to elaborate if you want to.

BTW: If there is only one Transformer with only two Primary feeder conductors to it, that would be, of course, a Single Phase system. This would be where you would find a center tapped transformer with some connection to that center tap - either a Neutral Conductor, or just a point for grounding.
This was the one I am curious about. If the transformer has the center tap grounded, that lowers the voltage to ground by 1/2 [half of the transformer's winding's potential]. If it's only grounded at the transformer and there is no physical wire coming to a service, which gets bonded to the metal enclosure and possibly grounded once again, that leaves a poor path for ground fault current. The path is in the dirt only.
I am almost completely positive that your systems are not done this way, but if they are please let me know.
The center tap and conductor from it to the service would not be used in any circuits.

If the 1 phase transformer was 230/460 VAC, then the center tap would be used as a typical Neutral Conductor, being part of circuits, along with the typical ground bonding stuff.

So you use 50Hz.. That's about the lowest frequency that is practical when multi use power distribution is concerned.
60 Hz is about the highest [which is what we use].
These Hz values are the best "Happy Medium" for plain old general use power, which is transmitted over a distance more than 25 miles and is to be used in high levels.

The Skin Effect, which greatly effects large conductors, is a little lower for the 50 Hz power. The trade off is a lower Synchronous Speed for the AC. This results in Transformer Cores and Coils that are a little larger. plus a little more lossier than their 60 Hz counterparts, plus general usage type Induction motors will have a max speed of 3,000 RPMs, as compared to 3,600 RPMs using 60 Hz.

25 Hz would be good to overcome Skin Effect, but would require large, lossy transformer cores - and Induction motors would max out at 1,500 RPMs. Not only that, but there would be a noticable flickering of lights when the sine waves crossed the Zero line.

400 Hz would improve the efficency of transformers, plus lights - along with giving a high speed to Induction Motors [24,000 RPMs], but the Skin Effect losses would be dramatically raised at this frequency. That's why 400 Hz is used on low to medium powered systems that are locally derived.

Just my $0.02

Scott SET

Scott,

Years ago I worked for a company that manufactured Avionics Test Equip that went aboard Carriers and also 'Portable' equip. for analyzing Aircraft systems. It used 60Hz and 400Hz.

Bill

You lost me a bit on some of that Scott, I am always keen to learn so if you have more i'd like to read it

The only significant difference I noticed in the distribution systems, of New Zealand, was the absence of dual voltages to a residential service. 230 volts single phase, one conductor earthed, is standard.
A transformer bank, with three separate, single phase units is connected wye, with the mid point connected to a MGN system, the same as common in the US.
The secondary winding has one insulated terminal, the other end of winding is connected to a tank ground pad.
The MGN system is landed on this pad, and then becomes the service entrance grounded conductor.
Secondary earthing is the same as we perform.
A single bank can provide 3 phase 400 volts and single phase at 400 and 230 volts.
The advantages I could see was: only two conductors supplying all residential loads. No loss of neutral mid-point connection, problems. Smaller wire for loads, with less voltage drop.
The 230 volts to ground does not appear to be a problem. Statistics I have seen, actually indicate less risk.

Thanks Bill

[This message has been edited by Bennie R. Palmer (edited 03-24-2001).]

Bennie,

Not related to the conversation here, but I wanted to mention to everyone that there's no reason to ever have 2 Edit messages on the comment because you can edit them out too. Next time you go in just erase any edit messages you see. You will always have 1 but no need for any more.


Bill

Ah..,Yep? No? maybe geez... im lost,this is all pretty new to me. I have been installing security systems for the last 12 years.
I know the max you can get from one phase and neutral is 230v(phase voltage) to get 400v(line voltage) you'd need at least two phases add a neutral and you would have the option of 2 times 230v ..the following is from one of my Text books; Multiple Earth Neutral System, This system of distribution uses the multiple earth neutral or MEN system.the neutral conductor is earthed at the source of the supply and also at one or more other points along the distribution line, and each consumers premises. the resistance between any point of the neutral conductor and earth must not exceed 10 ohms. The neutral is multiple earthed so that, if any live part of the supply system or consumers distribution system comes into contact with earth, current flows back to the neutral by way of parallel paths,and the net resistance of the fault current is low. the lower the resistance of the fault path, the higher the fault current - quick opperation of fuse or circuit breaker.
ADVANTAGES; 1. the greatest voltage to earth at any part of a consumers installation is phase voltage 230 volts
2. parallel low resistance paths are provided for fault current
3. the resulting high value of fault current ensures that protective devices operate effectively.
4. if a customers neutral is broken fault current can still flow back to the point of supply through parallel earth and neutral connections at other premises
5. some protection is provided from lightning and high voltage flashovers
DISADVANTAGES
1. the high fault current drings increased risk of fire or shock if it flows through poorly made connections or joints.
2. A broken neutral is sometimes not noticed because the earthing system carries the neutral current.
3. all exposed metalwork assoicaited with wiring systems must be earthed.

Appy;
we do 25 ohms or less. I see you go for 10, i'll bet that it is harder to achieve. Is there any particular way that you would gauge this???