> In Australia mains wiring differs in one significant factor to the USA. In every mains distribution unit ( fuse box ) the neutral wire is bonded to the ground wire and the physical ground stake.
At a low-voltage (120V here, 230V there) outlet, there is no "Neutral". Neutral is part of a three-live-wires power system; the Neutral carries the difference between the other two conductors (240V apart here, 460V apart there; a 230V/460V-split may not be delivered to most houses.)
With that correction: This has been true in the US for 100+ years.
Inside the house after the fusebox, for each circuit:
* There is one or more "hot" wires.
* There is a groundED wire. This is generally the Neutral of the power source (feeder or street-line), but is not generally a neutral inside the house (little or no load-current-cancellation). In the US after about 1920 this must be marked White.
I know you use a different color, but I will call the groundED wire the "white wire".
* And there is the groundING wire. This must NOT carry current in any normal condition. It must be left un-burdened to handle any fault current. In the US this must be Green or Bare.
groundING and groundED are tied together only at the service entrance (fusebox, with odd exceptions). groundING goes to dirt rod, interior metal pipe, and other earthy electrodes (this is a sore-spot which must be handled by a Licensed electrician).
mulletchuck's question relates to the wall-outlets, NOT the main distribution box.
In the US up past 1900 (NYC was electrified very early) there was no requirement to identify (white paint) the groundED current-carrying conductor. By 1920 we had to do this; but in the 1928 building I know too well this white paint is mostly flaked-off. Even into 1962, most US wall outlets had two equal slots: a wall-plug could be inserted either way (so-called H-N swap half the time).
> swapping Active and Neutral is a dangerous practice and illegal.
Illegal in the US; but "dangerous"?
If not for the damned Edison Screw Lamp, it would not be dangerous.
Consider: is it safe to touch the white wire? It's grounded downstairs, right? Well as the top post shows, line-drop ensure that under load there will be a few volts from white to ground. But consider a very-common fault: the white wire is loose under its screw in the fusebox. (VERY common!) If it loses contact, and there is "any" load connected and turned-on, you can get killed touching the white wire. The smallest incandescent night-light is plenty of current to be lethal; a 3-watt clock is over the let-go current. (Read your code: are over-current fuses/breakers allowed in your "white" wire? That's not safe; however it was common in the US through 1920.)
If you can get a full 120V shock from White, and you are not using a Neutral (current-canceling) connection, what IS the difference? You must insulate White the same as Black. You must not touch it "live". Gear must stand 120V on White.
> This forms part of the functional circuit of the earth leakage circuit breaker
No. The function of a "ground fault" breaker does not rely on a ground wire. At least not in US practice: we sense the DIFFERENCE between the two current-carrying conductors. Some write-ups of UK ELCBs suggest otherwise, that they fail to detect fault current which does not flow through the ground rod.
> illegal. Indeed i'd imagine that a landlord here would be required by law....
Ah, here we come to mulletchuck's dilemma. There is no Federal Electric Code in the US. In dense cities, concerned persons proposed electric codes to city government, when adopted by city government that code became Law in that city. Of course different code in NYC and Chicago and Boston; and smaller cities did not have the resources to write their own codes. The Fire Protection group NFPA organized the National Electrical Code. _IF_ adopted by a city or town, it then becomes Law in that town. (It's free to adopt; they charge electricians for the book.) In some areas, the Electric Utility enforces a Code or they will refuse service. If a town/utility wants a Code to be followed, they must appoint or approve Inspectors to check the work. BTW: my town had no Code (electric or building) until a few years ago.
Of course mulletchuck's city, NYC, has a massive Electric Code. (It is probably harmonized with the NEC, but goes on to add things not covered by NEC.) If he wished to build a new building, he would have to study the Code to know how it should be wired. But also a large old city works in strange ways. Inspection in NYC is a real sore spot: many incidents (maybe not too many considering the city size) have revealed lax or corrupt inspections.
A particular side-effect of this local adoption and enforcement is that city government is careful not to OVER-inspect. If a vocal group of citizens gets angry at the code and inspection process (landlords are organized and some make massive political contributions), the current city government gets yelled-at and potentially voted-out (never as the only issue, but maybe the 2% margin of defeat or lack of support). Existing working in-use wiring is almost NEVER Inspected and even less often required to be brought up to Current Code. Since mulletchuck's building is probably quite old, the situation he describes may have BEEN legal when it was installed and at each repair (the 3-pin outlets are surely newer than the building; the case of replacing old broken 2-pin outlets now that 2-pins are not available is murky).
While mulletchuck says "Not a safe situation", in fact if his gear is post-1970s then the tingle he feels is "generally accepted as safe". There is a 10:1 margin between "tingle" and "can't-let-go", more margin to "possible death". The exact thresholds vary among people and days (today mulletchuck is probably hot and sweaty and extra-conductive; look at NYC weather), and leakage happens; the "acceptable" leak in those RFI caps is a compromise which seems to be very OK.
If it screws-up his audio, that is not the problem of the NEC or his landlord. Neither promised him an ideal studio situation. Audio-guys may fight/fix their power troubles, but often it is wiser to build audio gear to perform well under "ANY" odd power situation. Telephone, radio stations and networks ran miles of audio between completely separate power grids; and until the late 1930s power grids were generally not interconnected more than 100 miles apart. (In 1950 Columbia Missouri's generator ran free of anything else in the world.) Transformers work wonders across hundred volt differences.
