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#141490 08/24/04 02:19 PM
Joined: Aug 2001
Posts: 7,520
pauluk Offline OP
During my enforced non-internet period last week I had time to finally have a quick read through AS3000:2000 -- The Australian and New Zealand wiring rules (PDF courtesy of one of ECN's antipodean members -- "Good on ya, mate!" [Linked Image]).

A few things which caught my attention:

1.8.2 Supply characteristics
(c) Voltage and voltage tolerances.
NOTE: The nominal voltage and tolerances for low voltage supply systems
and electrical installations are:
(a) For Australia, 230/400 V +10% −6% (in accordance with AS 60038); and
(b) For New Zealand, 230/400 V + 6% to −6%.
I hadn't realized that Australia had adopted this weird assymetric tolerance to fiddle the figures. When did that happen?

Quote Switches in neutral conductors
A switch or circuit-breaker shall not operate in a neutral conductor of —
(b) consumers mains; or
With MEN system as used down under, the bond is between neutral and earth bars within the main panel, right?

In a single-phase panel here the main switch always opens the neutral, but then our N-E bond (where used) is before the meter.

I think this rule illustrates the different approach quite well.

(c) a submain where the neutral is used for earthing of an electrical
installation in an outbuilding in accordance with Clause 3.5.2(c); or
Which doesn't happen here, as no neutral-earth bond would be used in such a case.

Quote Marking of cables entering or leaving a building
In New Zealand, marker signs shall be provided where a cable enters or
leaves a building.
What are these like? Are they like a downward pointing arrow stuck on the side of the building or something like that? Mike, do you have a pic of these by any chance?

Quote General
In general each socket-outlet shall be individually controlled by a
separate switch complying with Clauses and
This requirement need not apply where —
(a) two socket-outlets are located immediately adjacent to each other, in
which case one switch complying with Clauses and
may be used; or
(b) a socket-outlet installed for the connection of a fixed or stationary
appliance or a luminaire is —
(i) rated at not more than 10 A; and
(ii) not readily accessible for other purposes.
Hmm... That's different. Switched sockets are pretty much the norm here, certainly as far as residential and light commercial is concerned, but they're not a requirement, and you can install unswitched types throughout if you wish. The only time switches were required by IEE Regs. was for DC supplies.

Also of interest is section 6.3.3 which specifies rather different RCD test requirements between Australia and NZ.


[This message has been edited by pauluk (edited 08-24-2004).]

#141491 08/24/04 09:19 PM
Joined: Jul 2002
Posts: 8,419
Likes: 3
Looks like you had a good read of that PDF!. [Linked Image]
OK, regarding the Voltage Drop figures for Australia, I'm not entirely sure what the reasoning behind the +10 -6% is, but I can guess that AS 60038 (Standard for standard Low Voltages) may have a bearing on this.
Also, bear in mind that Mains cable runs may be a bit longer in Australia and these figures may be to ensure that adequate voltage is available at the Installation.

With and the interruption of Neutral conductors, the term "Consumers Mains" refers to the part of the supply cable that runs from the supply lines to the metering and the Main Switchboard, ie: before the MEN point.
This ensures that the Neutral conductor is fed to the Neutral busbar un-broken, because with the MEN system here, the Neutral and Earth conductors form the Fault current path and should the house next door have a faulty Earth electrode, the houses on each side of the faulty house will have thier MEN system carry the Fault current, through the Neutral. [Linked Image]

With respect to U/Ground cable marker signs,
Paul, it has always been required that an approved warning sign be affixed to the wall directly above a cable entry/exit point on a building.
Here's an example, sorry that it's on the front of a PoCo pillar box, but the format is the same:

[Linked Image], gives guidance on the use of socket-outlets without switches on the same plate as the socket.
Bearing in mind, that ALL sockets, regardless of type and current rating, must have a suitable isolation switch installed upstream of the associated socket-outlet.
The main use of Un-switched sockets here, is for Dishwashers, fridge/freezers and the like, where they are built into kitchen furniture and the switch still needs to be accessible, for Emergencies.
Timers are used quite a lot here, usually as a convenience thing, for Security lighting, pumps and Air Conditioning/Heating control.
Hope I haven't rambled on too much!. [Linked Image]

#141492 08/25/04 03:07 AM
Joined: Sep 2002
Posts: 1,498
Likes: 1
C-H Offline
The interval is probably assymetric for the same reasons that the UK has 230 +10/-6% and Sweden has +6/-10%. As New Zealand was already on 230V, it would have been rather odd of Australia to ask NZ to switch to 240V to create a common market...

You can check the year the standard was issued.

Somewhere on the net there is a pdf with results from test conducted prior to the change. I didn't bookmark it. [Linked Image] The Australians tested (new) 240V equipment (computers etc.) to see what it really worked with. The result was that it worked better with undervoltage than with overvoltage. This hinted that the 240V marking was a marking, not the design voltage.

Dapo might know more about this.

#141493 08/25/04 06:35 AM
Joined: Jul 2002
Posts: 8,419
Likes: 3
Over here, even though we have a 230V system, I can always measure 240V at the outlets here in my office.
The 230V, is only a Nominal value. [Linked Image]

#141494 08/30/04 06:49 AM
Joined: Aug 2001
Posts: 7,520
pauluk Offline OP
Thanks for the pic Mike -- I thought it would look something like that.

On the assymetric voltage tolerances, it sounds as though you're doing a similar fiddle down under as has happened here to accommodate a standardized nominal supply voltage.

Ever since the U.K. standardized on 240V our allowable tolerance was +/-6%. The change to 230V +10%/-6% was just to comply with the new European 230V standard without actually changing anything!

Check the figures:

240V +/-6% gives a range of 225.6 to 254.4V.
230V +10%/-6% equates to 216.2 to 253V.

Unless a current 240V supply is more than 5.4% over nominal (very rare in my experience) it still lies within the permitted new tolerance.

As C-H pointed out, Sweden has gone from 220 to 230V nominal by adopting 6 and 10% in reverse:

220 +/-6% ---> 206.8 to 233.2V
230 +6%/-10% ---> 207.0 to 243.8V

I've seen references which indicates CENELEC will move to a specification of 230V +/-10% eventually. If so, then why did we not just adopt that straight away, as it's a wider tolerance than our existing specification? [Linked Image]

[This message has been edited by pauluk (edited 08-30-2004).]

#141495 08/30/04 01:26 PM
Joined: Sep 2002
Posts: 1,498
Likes: 1
C-H Offline
In fact I don't think the spec was as strict as 6% back in the 220V days. I think I read many years ago that the change from 220V to 230V didn't make much difference as the tolerances were narrowed.

As for the +/-10%: It's clear that they couldn't expose old 220V equipment to 253V and needed a softer transition. As the transition tolerances are smaller than the proposed future tolerance, it becomes a mystery why they would adopt +/-10%. Apparently, we weren't the only people to feel this way. The change which was originally planned for 2003 has been postponed till 2008. Standardising on 230V +/- 8% (212-248V) would make more sense. Everyone would move closer to the nominal voltage and the power quality would in effect be better than presently, without any investments in the distribution system. A shift to +/-6% would require network upgrades, which in the end means higher bills for the consumers.

#141496 08/31/04 02:45 AM
Joined: Jul 2002
Posts: 8,419
Likes: 3
Not until we took on the Australian Standard for Voltage drop limits, did the Authorities here think that they could get away with more Line Sags, and we were the worser off for it.
Prior to that, you could go anywhere within NZ and measure with a T-RMS meter and find the voltage at any Consumers switchboard, within 2.5% of the nominal 230V, we had Auto-Tap Changers to ensure this on the HV lines and constant monitoring of line voltage here.
Now that we have such a wide variation in voltage, no-one seems to care anymore about supply quality.
And sure, most appliances are designed with this in mind, but is it good from an Operational point of view, on the part of the Network Operators here?.
To me it means slackness!. [Linked Image]

#141497 09/18/04 04:45 PM
Joined: Jul 2002
Posts: 8,419
Likes: 3
A rather strange move in the adoption of AS/NZS 3000, is the inclusion of Livestock.

1.7.3 Protection against direct contact:
Persons and livestock shall be protected against dangers that may arise from contact with parts of the electrical installation which are live in normal service.
Does this include electric fences?.

#141498 09/19/04 04:33 AM
Joined: Aug 2001
Posts: 7,520
pauluk Offline OP
Unless there is an exception somewhere else, then strictly speakly I suppose it does!

I think this electrical device would probably fall foul of that section as well if you used it down under! [Linked Image]

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