On Wed, 02 Jul 2008 09:34:12 -0700 Steve Urbach
<dragonsclaw@[EMAIL PROTECTED]
> wrote:
| On 2 Jul 2008 12:53:23 GMT, phil-news-nospam@[EMAIL PROTECTED]
wrote:
|
|>| If you need 240 V, you have it in most houses. Call your
electrician.
|>
|>My point is the losses in the _wiring_ are less at 240V than at 120V.
For
|>the wiring going into the home, which is sized for the expected total
current,
|>there's no issue since half the 120V loads being in series with the
other half.
| Huh! The only time that happens is when there is something really WRONG
with
| the Neutral conductor. Evidence: Bright lights in some places and dim
ones
| other places.
| I have seen this effect 3 times in 30 years. In all cases, there was a
(BIG)
| problem with the Neutral feeding the panel.
You are interpreting what I said in light of a different concept. I'm
merely
saying that we have a series type system (that does happen to be balanced
out
with a neutral in the middle when it is out of balance). That just means
we
do treat our system as a 240V system at points like the service drop.
|>120V loads makes it effectively 240V. However, for individual branch
circuits
|>using smaller (AWG #12 and #14) conductors, 240V would be less lossy
than 120V
|>is.
| Actually the loss is almost EXACTLY the same for a 2000VA load .
| We will assume that the countries that use 240 also use less copper to
deliver
| it to the outlet, so halving the current does not gain much I squared R
| efficiency. The USA uses 12Ga to deliver 20Amps of either voltage to the
| appropriate outlet with an estimated 5% voltage drop at 100 feet at the
full
That voltage drop will be 1/4 as much for the same power level on the same
wire size when using the same load. But even when you double the load,
you
have half the voltage drop in terms of percentage of the working voltage.
AND ... when you double the load on the circuit, you only need half as
many
circuits. Think about how the branch circuits would be wired in a 240V
system.
Two scenarios (as well as a range between them) are possible:
With a 2000VA load on a 120V circuit you have a certain loss. With a
4000VA
load on a 240V circuit with the same wiring, you do have the same loss
there
on that circuit. BUT YOU HAVE HALF AS MANY CIRCUITS! So you have half as
much loss!
| 20 Amps. Note a 20 amp circuit must be "de rated" to 80% if the load is
| present continuously for greater than 3 hours: "80% rule". I have seen
many
| "server room" 20A rated (5-20R) Ivory outlets that did not follow the de
| rating: Coffee colored and crumbling when plug removed. Since the load
was NOT
| over the breaker rating, the breaker did not trip.
The 80% rule is irrelevant to the 120V vs 240V issue. We'd be keeping the
same rule either way.
| Using less copper sound$ good to me.
Half as many circuits ... half as much copper.
The reality is the circuits would not be quite half due to the need to
reach
as many places for spread out loads. But to the extent that happens,
loads
would not be "piled up" on the same circuit, and such lesser loaded
circuits
would have less power loss.
| Most of my larger electronics is voltage switchable (some needs a
| jumper/switch move), Unfortunately, most of my "wall wart" powered stuff
is
| only 120V.
There are _some_ wall warts that can do 115/230 (switched) or 100-240
(range).
--
|WARNING: Due to extreme spam, googlegroups.com is blocked. Due to
ignorance |
| by the abuse department, bellsouth.net is blocked. If you post
to |
| Usenet from these places, find another Usenet provider ASAP.
|
| Phil Howard KA9WGN (email for humans: first name in lower case at
ipal.net) |
|
