[Elecraft] Curiosity Only, somewhat off topic.

[Milt -- N5IA]

David,

The standard residential service in the US of A is 120/240 Volts AC.

It is provided by the center tapped secondary winding of the utility
transformer.  The center tap is grounded and becomes a Neutral such that in
the home you have two 120 VAC legs, one from each of two ends of the
secondary winding.  The two legs are 180 degrees out of phase to each other,
and separately are used with the grounded neutral to provide the 120 VAC
service.

For larger appliances such as stoves, ovens, hot water heaters, clothes
dryers and Amateur Amplifiers, the current is sourced by connecting to both
120 VAC legs, resulting in 240 VAC being delivered to the appliance.  No
additional step-up transformer is required.

There is no free lunch.  The laws of physics cannot be changed.  It is just
a different scheme of power delivery which allows a grounded neutral to be
carried to each small appliance or lighting fixture.

I hope that helps a bit with your understanding.

Milt, N5IA


-----Original Message----- 
From: David Dunn
Sent: Wednesday, December 14, 2011 3:04 PM
To: elecraft at mailman.qth.net
Subject: [Elecraft] Curiosity Only, somewhat off topic.

I noted recently several refs by USA users asking about 240 volt ac power
plugs etc.

Now I have never even been to a 110v  country -  possibly only USA ? -
and
I can see a degree of (shock)  safety offered with that system, but I can
hardly imagine the mass of copper required to carry possibly 200 amps
around the house.   Nevertheless, I just wondered why there seems such
interest in running 240v equipment, presumably via suitable transformer.
                     David VK3DBD/G3SCD.
.
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