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BaronJ
14th Jan 2019, 03:11 AM
Hi Guys,

Having read the threads below, the question does pop into my head, Do you use "ring main" wiring systems in AU ?

Darryn
14th Jan 2019, 03:22 AM
No not like you do in blighty!
Also no fuses in our standard 3 pin plugs either.

RustyArc
14th Jan 2019, 01:55 PM
As mentioned, we don't, but I do like to talk about running ring mains and using wire nuts when winding up Australian sparkies on forums who are convinced we're all doing illegal DIY wiring.

BaronJ
15th Jan 2019, 03:04 AM
Thanks Guys,

It is interesting learning about the different systems and practices in different parts of the world. I didn't know about the lack of fused plugs for instance.

As far as wiring nuts is concerned, I thought that they were discontinued years ago !

NOTE: For some reason I can no longer activate any of the "likes, thanks or pictures" at the moment. Sorry !

A Duke
15th Jan 2019, 10:28 AM
Hi,
Yes most Australian sparkies get a shocked look when someone who has worked with such things describe it to them.
The Australian wiring regs specifically ban ring mains and fuses in plug tops.
Regards

lamestllama
15th Jan 2019, 11:43 AM
Hi Guys,

Having read the threads below, the question does pop into my head, Do you use "ring main" wiring systems in AU ?

No they are specifically banned. Testing their correct operation is a bit more complex. Our licence holders can't keep up with the safety record of NZ DIYers so it would probably be unwise to introduce more complexity into their lives.

BaronJ
15th Jan 2019, 09:46 PM
Hi Guys,

I'm somewhat surprised by that ! Ring mains have been the standard here for years now. Even so the regs specify the maximum number of 13 amp outlets you can put on a ring of a particular size core.

As far as I'm aware the ring main was introduced just after the war, because of the shortage of copper, and as time progressed became single copper cores rather than the multiple strand core of the previous domestic wiring. Higher capacity cables still use multiple strands.

.RC.
15th Jan 2019, 10:32 PM
Is the main point of the "ring" method that the electrical force has the opportunity to get to the GPO via two different paths?

what happens if you get a conductor breakage. Then wouldn't it potentially overload the cable as the electrical force can not longer travel both ways to the GPO?

lamestllama
15th Jan 2019, 10:46 PM
Is the main point of the "ring" method that the electrical force has the opportunity to get to the GPO via two different paths?

what happens if you get a conductor breakage. Then wouldn't it potentially overload the cable as the electrical force can not longer travel both ways to the GPO?

It has two main points. One is the higher current capacity for a given size of wire (given any allowances for type of enclosure) because you have two paths for the current. The other is that is the earth also is connected twice so a break in the earth affects less of the circuit.

BaronJ
16th Jan 2019, 07:24 AM
it has two main points. One is the higher current capacity for a given size of wire (given any allowances for type of enclosure) because you have two paths for the current. The other is that is the earth also is connected twice so a break in the earth affects less of the circuit.

Spot on. Right on both counts.

Not forgetting the additional protection of fuses in the plug. These have a maximum rating of 13 Amps and whilst there are larger capacity fuses, they are also physically much larger and will not fit into the plug top. These fuses are usually sold in packs of five or ten with ratings from 3 Amps, 5 Amps, 10 Amps and 13 Amps.

lamestllama
16th Jan 2019, 02:03 PM
Spot on. Right on both counts.

Not forgetting the additional protection of fuses in the plug. These have a maximum rating of 13 Amps and whilst there are larger capacity fuses, they are also physically much larger and will not fit into the plug top. These fuses are usually sold in packs of five or ten with ratings from 3 Amps, 5 Amps, 10 Amps and 13 Amps.

Not to forget the shutters in the socket operated by the longer earth pin that stop people sticking stuff into the live contacts without really really trying.

OxxAndBert
16th Jan 2019, 04:05 PM
Thanks Guys,
<snip>

NOTE: For some reason I can no longer activate any of the "likes, thanks or pictures" at the moment. Sorry !

Apparently its a bug since the upgrade on 13th - the admin has it on the todo list.
http://metalworkforums.com/f36/t202817-forum-update-post

Steve

BaronJ
16th Jan 2019, 10:06 PM
Hi Steve,

Thank you for that information ! I did think it was a Firefox bug following an update to it on my machine. When I click any of the four items the bottom of the page just blanks and I get a "JavaScript" failure message.

Grahame Collins
16th Jan 2019, 11:02 PM
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Glot
7th Apr 2019, 08:17 PM
The ring circuit was introduced in to the UK during the war to save copper. Each outlet is fed via two cables of half the size. The cable is protected but an overload device matched to the two cables in parallel. It's not a good system. One issue is a break in one cable can allow an overload in the other. However, this isn't as bad as it sounds when you understand how cable current ratings are calculated ( as every electrician should!).

lamestllama
7th Apr 2019, 09:34 PM
The ring circuit was introduced in to the UK during the war to save copper. Each outlet is fed via two cables of half the size. The cable is protected but an overload device matched to the two cables in parallel. It's not a good system. One issue is a break in one cable can allow an overload in the other. However, this isn't as bad as it sounds when you understand how cable current ratings are calculated ( as every electrician should!).

That story about saving copper during the war is not supported by any documentation at all https://en.wikipedia.org/wiki/Ring_circuit#History_and_use. To declare it "not a good system" is to ignore the crucial part of the system that actually makes it a very good system the BS 1363 (https://en.wikipedia.org/wiki/BS_1363) plug and socket system. We have waited nearly 60 years for Australian designed plugs and sockets to come close to providing the same number of safety features (shuttering and insulated pins). The reason why the ring main circuit wasn't adopted here is simply because the plug and socket chosen for commercial reasons https://en.wikipedia.org/wiki/AS/NZS_3112#History don't have the features (fusing) needed to make a ring main a viable choice.

The current wiring rules allow for radials in the UK yet still the most common installations are ring mains? Are UK electricians dumber than Australian ones? I doubt it they make their choices for valid reasons. The fact that it isn't a choice you could make means you probably haven't had any exposure to its advantages. For instance a broken earth in a radial system doesn't stop the system from working but makes it dangerous. In a ring main you get two earth paths.