"Andrew Gabriel" wrote in message
...
In article ,
"G&M" writes:

On Tue, 15 Jun 2004 14:35:10 +0100, "Christian McArdle"
wrote:

You are joking! US electrics are about as safe as attaching electrodes
to
your genitals.

Possibly - but with the US supply you'll survive this bit of
sado-masochism.

Earth - sorry ground - potential is somewhat hit and miss over there but
often it lies fairly centrally between the two wires so you've only got
55volts or so of shock.

You maybe thinking of a construction site supply in UK.
US supply is 120V with one side grounded, or 120-0-120V
if you have access to both hot legs.

--
Andrew Gabriel

I agree Andrew. There are three wires coming into my house which is
atypical for most homes built or rewired within the last 40 years or so. Two
conductors are at 120 volts RMS 60 Hertz AC above/to ground (earth). And
there is 240 volts RMS between the two live wires. 200 amp is minimum in
most cases, cos. of electric heating.
In other words we have a single phase centre tapped 240 volt supply. The
centre tap conductor is the neutral and is earthed, once (also earthed at
the electric utility distribution transformer) at the point it enters the
main CU of the residence.
So the maximum voltage to earth 'is' 120 volts RMS.
The two wires or legs each at 120 volts are sometimes, incorrectly referred
to as 'Phases' which they are not.
Could be confusing to someone when they do get into, occasionally, in some
commercial installations a real three phase situation.
Which here for small installations would usually be 208/117 Star/Delta with
centre point earthed. In fact our electric heaters, for example, are
listed/boxed with two ratings 230 or 208 volts. Same 'R' different 'V
squared'. About a 20% difference!
That centre tapped 55 volts to ground/earth construction site transformer
idea is ingenious and safer than North American 117/120 even with what are
called here GFI (Ground Fault Interrupter) i.e. same current unbalance
principle as an RCD, I think?