🚀 go-pugleaf

"Stupider than Anyone  Else"

>I have to phases of power supply to my house - so three power lines, two 
>phases plus neutral.
>
> I've on occasion wondered what would happen if we lost the neutral line. 
> It seems to me that we'd then have the voltage between the two phases 
> across two sets of appliances, one set attached to one phase, and the 
> other set attached to the other phase, with the two sets in series as a 
> result of their common connection to the neutral wire. Since the two sets 
> are unlikely to represent equal loads, the net result would be a large 
> overvoltage on one set of appliances.
>
> My electrician says it's not an issue, but I can't see why.


** Loss of the neutral conductor in a 3 phase ( or 2 phase) AC supply system 
can easily be a DISASTROUS  event.

For example:

In the live entertainment productions -  high powered lighting and sound 
systems operate from 3 phase outlets via a hefty 5 pin plug and socket.  If, 
due to wear and tear or damage to the plug or socket, one of the phases 
drops out  -  that is an annoyance but not a disaster.

However, if the pin carrying the neutral fails to connect or as is often the 
case *disconnects* during a show because of overheating   -  ALL HELL 
BREAKS  LOOSE !!

Typically, some of the lamps will glow very brightly for a second or two and 
fail, then other previously dim lamps will follow suit.  The AC fuses in 
amplifiers will pop instantly and some equipment will be seriously damaged 
when the PSU sections are destroyed. It all happens in a few seconds, while 
the operators stand there with their mouths open  !!!

The MEN system:

In Australia, AC power delivery uses a system called " Multiple Earth 
Neutral "  -  which requires that the neutral conductors in a premises be 
connected to the plumbing system at the distribution board (ie power box). 
It also requires that an earth stake be installed for the same purpose, but 
some older premises may not have this.

Because EVERY premises has MEN installed, the ground itself and underground 
metal plumbing act as an alternative neutral, should the supply conductor 
feeding a given premises fail. The disastrous event sometimes experienced in 
live entertainment systems is hardly possible in domestic or commercial 
premises.

So the sparky is right.



....  Phil