I remember one morning when I was about 12 - one of those Atlas Copco air compressors that are often towed behind tip trucks got a flat tyre and it swung into the path of one of those green kiosks pictured above. The damage was incredible, not to mention the blackout that made me late for school.

Yes to the 'patch in'. At strategic locations there are knife switches on the 240/415 wiring and these get closed when a substation goes pop. You have to look hard to find them but they are more common than most believe.

To switch the gist of the topic to operating US equipment in Oz.

I have been collecting early ('80s) cd players, some from US. To power these I picked up a transformer with a 120V socket (two pin) but no power cord for a few $s at a market. On pulling it apart to check it out for fitting the cord it turned out to be an autotransformer. Checks with low voltage AC indicated should get 120V out for 240V in.

Since the gear I have is all double insulated I don't see any difficulty or hazard using it. But is this right? Any words to the wise?

The other idea I had for this job was the autotransformer out of an old fan with switchable speed. But haven't checked the volts out for each speed setting yet.

Since the gear I have is all double insulated I don't see any difficulty or hazard using it. But is this right?

Apart from the lack of earthing, the main danger with autotransformers is that without an isolated secondary, a fault can result in 240v appearing on the output side with consequences for the attached equipment.

I use a 50VA Chinese one on my tube tester, but that's all. I got it because it is small and portable and suits the light load and intermittent use of the tester. However, as a rule, I don't like using autotransformers in mains applications if I can avoid it.

I have a big heavy Aussie made stepdown transformer from out of a jukebox with a 7.5 amp primary fuse which I use for anything else. When I got it, it was earthed on input to the case, but had an unearthed double 2 pin (NEMA 1-15) socket on the secondary side, which I subsequently replaced with a double 3 pin socket (NEMA 5-15),

Also, with the Chinese cheapies, I take their VA rating with a grain of salt, especially for continuous use. I'd de-rate their claimed VA by 20% for continuous use.

The other idea I had for this job was the autotransformer out of an old fan with switchable speed.

Personally, I wouldn't go that way. I'd get a good purpose built unit.

One thing to remember is that USA equipment's transformers would be expecting 60Hz and may overheat on 50Hz if the voltage you feed it is on the high side. Though some transformers may have enough iron core to handle the lower frequency of 60Hz (Japan has 60Hz in their southwest and 50 in their northeast, and they make their transformers capable of handling both, albeit at 100VAC). And there are a few places in the world (not many!) that have 120V50Hz and to cut inventory expenses and distribution control expenses they use transformers that can handle that.
Some equipment may have transformers that can be reconnected from 120V to 240V by moving jumpers or wires inside the box.

You can check the transformer for overheating to see if it's unhappy with 50Hz. Your thumb is a good measuring device.

Most power transformers and thus equipment they are used in are designed for "hi-pot" which is 1.4KVDC insulation quality, so the power transformer getting 230V to ground on one wire and 120V on the other wire on its primary shouldn't be a worry.

Thanks for your input gents.

My autotransformer has no rating on it but I would guess it should handle a couple of hundred watts by the size of it so I won't be overloading that with my 10 watts of cd player. Effectively unloaded its voltage might be a bit high though.

Some of the players have a switchable voltage so they would be safe from overheating from eddy current losses. That leaves the nonswitchables. The production runs, going on the serial numbers were large so it is possible that they would source transformers specific to AC frequency. Will have to open up some 50 & 60Hz non-switchable examples and see if the transformers have taps, or part numbers that would indicate a common transformer.

It was never my intention to use the autotransformer on anything but my double insulated cd players. However if I did have need to run earthed 120V equipment, can this be made safe by using an isolation transformer on the 240V side of the autotransformer? This presupposes replacing the 2 pin with a 3 pin 120V socket on the autoransformer.

"the common is connected to the 240V neutral"

This precaution would not work if as observed in other posts the neutral and active are transposed. I once got a nip from a cracked bakelite plug plugged into such a power point, even though the point was turned off. This experience encouraged me to get one of those plugs with three neons that shows up incorrect socket wiring.

The powerpoint was in my grandmothers house and was probably installed in the late twenties or early thirties.

Complete with pilot light and high on the wall its only use was to power her iron. The fact that she was never electrocuted or even got a tingle I put down to no steam irons then, rubber soled shoes, lino floor and good bakelite plug.
More points were installed during the late fifties and the iron went to another room in the house and the point in question was then used to power the radio. It was on top of the kitchen cabinet and I got my tingle when I lifted it down with one hand touching the chasis and pulled the plug with the other.

The rule of one only hand for the job reinforced.

Complete with pilot light and high on the wall its only use was to power her iron.

In 1968 I was at the house of schoolfriend Jim who sat next to me in class. It was an old place built in the 1920's or earlier. In the enclosed back verandah his mother was doing the ironing on an old board that folded out from a cupboard built on the wall. The GPO was as you describe, separate switch and socket complete with red pilot light atop it. It was not in good condition and I said at the time that I didn't like the look of that setup.

About six months later during first period I asked him if he could also smell a bushfire. He said, "It's me. It's my clothes. Our house burned down last night."

I went around after school and the house had been gutted by flames, with the worst of it at the rear. He said the fire started in the ironing cupboard and his mother recalled that I had commented about it earlier.

A sad story about the house burning down. I hope everyone was safe.

I once asked about the lamp bases on the old powerpoints and it took a couple of years to get a straight answer, especially since these were not fitted to every outlet.

Then one day someone told me it was simply because many appliances came fitted with bayonet adaptors, which was simply because not every house had wall sockets at the time.

When the habit of using bayonet adaptors fell out of vogue pilot lamps were then installed as a way of keeping fingers out of the lamp bases.

One other thing that intrigued me at a young age was the servants call bell system at my great aunty's place. It was electric and had a bell along with a pilot lamp showing which button had been pressed.

^ Yes, there was nobody at home when the fire started. He and his mum came home to find the street closed and fire brigade hosing down the embers. It was a big shock for everybody. I had never experienced such a thing. I can still recall the smell of the burnt out house as his mum showed me what was left of it.

I think that makes sense about the batten holders atop the old GPOs. As I mentioned earlier, my grandfather had a bunch of old appliances in his garage that had bayonet plugs on them.

However, in the case of the ironing board cupboard, I think it was to remind the user to switch off the iron as it had a metal shield around the pilot light, sort of like a valve shield.