🚀 go-pugleaf

In sci.electronics.repair kreed <kenreed1999@gmail.com> wrote:
> On Nov 24, 10:10 am, Sylvia Else <syl...@not.at.this.address> wrote:
>> 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.
>>
>> Any thoughts?
>>
>> Sylvia.
> 
> 
> You are both right and wrong as in the absence of Neutral line, a lot
> of the neutral current (imbalance) would probably flow via your earth
> stake back to the transformer neutral or to a neighbours neutral via
> their earth stake and while its not a perfect situation, imbalance
> probably would not be as bad as you might think ?
> 
> Of course, if there is a long run through earth (terra firma) back to
> the nearest neutral, the soil is really dry, the earth stake is sub-
> standard etc etc it might not work very well.
> 
> 
> 
> 
> 
> Years and years back I once saw the result of this at a 3 phase
> installation at a carnival, we were called out to fix
> 
> They would have with them, and take from site to site portable fuse
> boxes with a 3 phase plug, going to a box with breakers feeding rows
> of power points going to each phase (like in a normal building
> installation, but portable). They would plug in all their gear to
> these sockets, and plug the 3 phase into the 3 phase sockets provided
> at the venues.
> 
> Of course, a lot of the carnival workers would probably just plug
> things in at random, and who knows what load would be on the end of
> each lead.  There could also be very large numbers of flashing lights
> on one lead too, so the load would be less than perfect, and surely
> not anywhere near balanced or stable ;)
> 
> One case, the neutral lead broke off.  On one phase there was a lot of
> damage to computer gear / arcade games (same sort of thing -
> switchmode power supplies)  etc.  Some was just blown fuses, some
> worse.
> Note, they didn't have the earth and neutral bonded inside the box,
> and didn't have a separate earth stake, where in a home fuse box they
> would.
> 
> 2 phase situation like yours would be a similar result, unless the
> load was really well balanced, and consisting of mostly NON-switchmode
> power supply type devices.  The phase with the lowest load would
> suffer overvoltage.
> 
> This load imbalance and voltage difference would change all the time
> as various appliances automatically switch off and on, like fridges,
> air cons, electric HWS etc.  Light bulbs may blow from overvoltage,
> this would also change the balance
> 
> 
> 
> Try connecting 12v bulbs of different wattages in series across 24v
> and see what happens.  The voltage will not be the same across each.
> Much the same thing.

I actually had the neutral fail (break) a few years back during a
winter wind-storm. No deleterious effects. The imbalance (neutral)
current was carried by the ground, a copper water pipe that's probably
at least 10 feet below gound level and 20 0r so feet long.

	Jerry