Strange !
Here in Norway the standard is also 2 wire 230V in residential
areas, 3 Phase is becoming more and more common, but the phases
are often split to 2 wire 1 PH systems at the intake panel and distributed
indoors as 2 wire. The load is balanced by hardwiring.
There is no neutral or ground distributed. Both wires in the 2-wire system
is floating with respect to ground. Pole transformers are mostly, if not
always triangle configured with no neutral. Ground IS distributed on the
HV side but not the subscriber side. A ground rod near the intake panel
is mandatory, and this ground is distributed within the home to all rooms
where a grounded installation is present (water pipes etc) . or where an
appliance
calls for a grounded outlet. There are numbers for max ground resistance
allowed and min. current carrying capacity.
There is an obvious fire hazard and shock hazard here...if your neighbour
has a fault that puts one wire of a phase to ground, and you have a similar
( "opposite" ) fault...you may have a substantial ground current floating.-
this is considered very dangerous ! The obvious solution is to have a ground
leak protector at each of the 3 wires (2) at the intake panel.
These protect if there is a slight leakage to ground..( 10-15 milliamps or
more)
within the house. This is mandatory in all new installations, or when
upgrading
an older one with more fuses, bigger fuses etc.
This is clearly a big safety advantage, but has its negative sides :
They are more often than not RF-sensitive :-( and they also have a
bad tendency to trip under almost any and every thunderstorm within a few
miles... If you are away from home for the weekend during the storm season:
Expect to see your freezer converted into a swimming pool when you return
:-)
This of course can be avoided by installing overvoltage-protection
(MOV-TYPE)
ahead of the protection device. This is hardly legal...so please do not
check my intake panel :-)
Well...actually I am a very "legal" person, so my solution was to convince
my power
company that any lightning strike in one of my 100 foot towers probably
would spread
over their distribution system and cause severe damage :-) .. Their solution
was to install
a VERY heavy duty spike protector system at the 230V side in the pole next
to my home...
I had to pay 50% of the materials costs,- but not the labour. This was the
perfect solution
for me :-) !!! And : My towers ARE very well grounded ...I do not think it
would spread
that much energy...but I do not KNOW....do I ? ....
Peter
----- Original Message -----
From: "Ron Youvan" <ka4inm@tampabay.rr.com>
To: "amps" <amps@contesting.com>
Sent: Monday, April 04, 2011 5:06 PM
Subject: Re: [Amps] what is a 4 wire 240VAC service?
> Jim Thomson wrote:
>> Date: Sun, 03 Apr 2011 10:51:58 -0700
>> From: Jim Brown<jim@audiosystemsgroup.com>
>> Subject: Re: [Amps] what is a 4 wire 240VAC service?
>>
>>
>> On 4/3/2011 7:57 AM, Charles Harpole wrote:
>>> Maybe being in Thailand, where 230vac is supplied with TWO wires, makes
>>> me ask.... what is 4-wire 240vac service?
>>
>> ## In Thailand,.... and the UK, etc,,..sure they give you 230 vac from
>> the street..BUT one of those
>> two wires is GRNDED at the pole. In essence, you have 1 hot and one
>> neutral/grnd coming in off
>> the street. So you are getting UB balanced 230 vac, Here in nA, we
>> get 240 vac balanced power....and the sec
>> of the pole pig is the neutral..which is also bonde to grnd....and also
>> bonded to the return wire of the 14.4 kv.
>
> For those outside of the USA the following is how we do it in the
> U.S.A.: http://en.wikipedia.org/wiki/Split_phase
> --
> Ron KA4INM - Endless Loop: n. see Loop, Endless.
> Loop, Endless: n. see Endless Loop.
> -- Random Shack Data Processing Dictionary
>
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>
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