My notebook PSU used in soldering station has 1M resistor with parallel capacitor between earth and output ground, other one layin' around has 0.1R measured with multimeter, so its definitely hardwired by the manufacturer.
I use the first one, AC multimeter shows about 0.4V and 0.04mA beetwen tip and earth connection but it is able to lightly glow red LED, which blinks with a similiar frequency as the heater.