[Amps] What to do about 'Neutral' in HB amp?

[Paul Christensen]

>"Here we have a MEN (Main Earth Neutral) connection at the switchboard. Power circuit are also RCD protected"

Adrian,

>From your description, it appears Australia's residential distribution uses a 240V single-phase secondary from the utility company to the home with ONE SIDE of the 240V feeder bonded to an earth conductor at one point: the main service/switchboard panel.  This forms the basis of your neutral.  Please re-describe if this isn’t correct.

By contrast, U.S. residential service also uses a single-phase 240V distribution, but with a tapped secondary from the utility transformer which gives us 120V-0V-120V 180-deg. split-phase, where the 0V tap is used as a 120V current-carrying neutral and is bonded to an earth conductor at the premise's main distribution panel.

>"When the neutral breaks/opens you get the full effect of the electrical shock. All appliances here, as well as the wall outlet must be switched in the active."

In the U.S., we also switch only the active lead, never the neutral.  

>"At least you should install a sw/brd RCD (residual current device ) aka ELCB to trip the active, if you do get on the end of a live chassis."

In older U.S. homes without a third-wire receptacle grounding conductor, it's common to upgrade the branch circuit with a GFCI device (AKA your ELCB). This solution can avoid a massive system rewiring.  I recently rewired my daughter's 75-year-old home this way.

Paul, W9AC