Transformerless Power Suppply

[rmteo]

Something like this PSAA60W-120

AC Input Voltage Rating: 100 to 240V AC
AC Input Frequency: 50 to 60Hz
Input Current: 1.6A at 100V AC, 0.7A at 240V AC
Output: 60W
Efficiency: 85% average

[comwarrior]

transformer-less... the above has a transformer, i can tell because of the input specification.

Here in the UK the current code for mains wiring dictates the use of an ELCB.
Earth Leakage Circuit Breaker. If more than 50mA flows up or down the earth wire the ELCB will trip isolating both live and neutral.
every time I've diagnosed wiring faults, their has always been a 50 to 60 V AC difference between earth and ether neutral or live...
If you use an isolation transformer you can connect the negative after rectification to ground. This is what most PC PSU's do.

edit:
That efficiency rating is crap!