Miche > wrote in
on Jul Fri 2009
am

> In article >,
> bob in nz > wrote:
>
>> On Thu, 16 Jul 2009 21:54:20 -0500, "Pete C." >
>> shouted from the highest rooftop:
>> >
>> >bob in nz wrote:
>>
>> <snip>
>>
>> >> We have what's called 3-phase power and no-one can explain it to
>> >> me.
>> >
>> >Nothing magic about three phase power.
>> >
>> >Your ordinary table lamp as an example plugs into a 120V single
>> >phase circuit, there are two wires, one "hot" which is the 120V AC
>> >source and one "neutral" which is the return to complete the
>> >circuit. With three phase power there are three separate "hot" lines
>> >that come into the building along with one common "neutral".
>> >
>> >The reason you sometimes loose power to parts of the house is that
>> >outside of three phase motors, virtually everything you have in the
>> >house runs on single phase power and is hooked up to one of the
>> >three "hot" lines coming into the house. A falling tree in a storm
>> >can land on and break or short out just one or two of the three
>> >lines on the distribution poles, so you may still have some powered.
>> >Outside of three phase motors, there isn't much that actually uses
>> >three phase power in it's entirety.
>> >
>> >In the US we use single phase power for homes and three phase power
>> >for commercial and industrial buildings. With single phase power,
>> >even though all primary utility power distribution is three phase,
>> >the single phase low voltage feeders that feed a house are fed by
>> >transformers that only receive power from one of the three primary
>> >lines on the pole, so a tree taking out one of the primary lines
>> >will either take out all of your power or none of it.
>> >
>> >This is a very simplistic explanation, so no flack from those of you
>> >who know the details, I know them too.
>>
>> Many thanks for that. Even I can understand it now. Turns out that
>> one of our neighbour's trees had shorted out one of the lines but not
>> the others.
>>
>> BTW - we run on 240v in New Zealand.
>
> 230V, 50Hz.
>
> 3-phase is 400V.
>
> Miche
>

each household phase is around 110v-120v...most houses use 2 phases in their fusebox/braker
panel. Each side of the fusebox is a different phase. This allows the creating the 240 v feeds to
various stuff. If you lose lights oe power in some numerous rooms but not others, it can be a loss of
a phase.

Usually the loss of 1 phase or half the power in your house is a outside the house issue.

I know this as a cruel winter storm caused me to lose 1 phase...drove me nuts trying to figure why
half the plugs in some rooms would work and why the fridge wouldn't work but the stove light
would.

A IBEW lineman guy came out and reconnected the broken splice up the pole and viola lights
everywhere.
IBEW...international brotherhood of electrical workers, which being a telephone blue collar worker
myself, I also belong to.

I work with DC whereas he works in AC. I work with amps high enough to scare electrians but only
50v. It's the amps that kill and do bodily damage.

--

The beet goes on -Alan