Re: Safety Grounding.
First, the two "hot" leads; red, and black (or more correctly black and red)
have single phase 240 across them. The white or neutral will have no current
in this case, but still needs to be connected. The 4th wire, or green is
earth ground. This is separate from the neutral white which although it may
wind up on the same terminal strip in the box, are actually two distinct
conductors and have to be connected for safety, many 240 volt outlets only
use these three wires, no separate earth ground.
Now in this 240 case no current in the white wire.
In the case of 120, either black or red has current and the neutral carries
the return on the 120 circuit or the same current in each conductor. If
another
120 volt circuit is connected to the other hot lead the total current in the
neutral should diminish as the phases from these two loads tend to cancel.
So 20 amps at 240 equals 20 amps each 120 volt circuit all using the same
size
wire. If the phases did not add in the way described the neutral would have
to
be larger. For example 20 amp wiring is 12 gauge. If the return were to add
arithmetically we would need #8 (40 amp)for the neutral, but we don't, we
just
use the same #12.
Hence the beauty of Mr. Steinmetz's AC circuit engineering.
ed K0KL
-----Original Message-----
From: amps-bounces@contesting.com [mailto:amps-bounces@contesting.com]On
Behalf Of amps-request@contesting.com
Sent: Tuesday, July 04, 2006 11:01 AM
To: amps@contesting.com
Subject: Amps Digest, Vol 43, Issue 25
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Today's Topics:
1. Re: L4-B Power Supply (Gudguyham@aol.com)
2. Re: Safety grounding - was Mains Isolation Transformer
(Gudguyham@aol.com)
----------------------------------------------------------------------
Message: 1
Date: Tue, 4 Jul 2006 11:49:36 EDT
From: Gudguyham@aol.com
Subject: Re: [Amps] L4-B Power Supply
To: radio_k4rv@peoplepc.com, amps@contesting.com
Message-ID: <3f5.587be20.31dbe810@aol.com>
Content-Type: text/plain; charset="US-ASCII"
In a message dated 7/4/2006 11:15:36 A.M. Eastern Standard Time,
radio_k4rv@peoplepc.com writes:
Most of the capacitor choices I found were of the type using snap in
terminals. Into what do these terminals snap? Can I just mount the
capacitors and then solder leads to their snap in terminals, or is there a
snap in receptacle of some sort available?
Thanks
Tom K4RV
Tom, I have rebuilt a few L4B power supplies, I use 390mfd/450v snap in
caps(which I sell for $2.50 each) I drill small holes in the original
circuit
board and fit the snap in caps tightly in the holes and then solder point to
point wiring to them. If you are interested in purchasing some of my caps
send
me an e-mail off list. Thanks 73 Lou
------------------------------
Message: 2
Date: Tue, 4 Jul 2006 11:57:00 EDT
From: Gudguyham@aol.com
Subject: Re: [Amps] Safety grounding - was Mains Isolation Transformer
To: r@somis.org
Cc: amps@contesting.com
Message-ID: <494.4a49d9f.31dbe9cc@aol.com>
Content-Type: text/plain; charset="US-ASCII"
In a message dated 7/4/2006 10:41:43 A.M. Eastern Standard Time,
r@somis.org
writes:
What kind of plug would it have?
It would have the basic 240 volt receptacle which requires no neutral
connection. Like the receptacle that one would plug an Ameritron AL-1200
or the
like. I think the confusion here is in terminology rather than
understanding.
A 4 wire system that is NOT 3 phase is considered to be a 240/120 volt
circuit. THAT is the correct terminology. A 3 wire circuit could be your
basic
120 volt with a bond or a 240 volt with a bond. Lou
------------------------------
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