[Amps] what is a 4 wire 240VAC service?

[Jim Thomson]

Date: Sun, 03 Apr 2011 10:51:58 -0700
From: Jim Brown <jim at 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. 

##  IE: the 14.4 kv pair of wires  coming dowen the street.... the lower one is grnded. 





Charles,

There's a tutorial on Power and Grounding for Audio and Video Systems on 
my website that explains most of what you want to know, and it covers 
variations in practice over most of the world.  
http://audiosystemsgroup.com/publish.htm

Inside buildings, an appliance like a clothes dryer that needs 240V 
power, would get both sides of 240V plus the ground.  IF that appliance 
also needed 120V power, the neutral wire must also be connected, and the 
120V load must be connected between one side of 120V and neutral.

###  here's where they scrwed up with 30A  dryer  circuits imo.   They shoulda
just used a 240 vac motor to turn the drum instead of  a 120 vac motor.   Then the neutral
wouldn't be required.    These days, dryers have several heat settings..and the neutral is used. 

Jim   VE7RF






The same standards (and laws of physics) apply in your part of the 
world, except that voltages are multiplied by two and currents are 
divided by two for the same load.

73, Jim Brown K9YC