In article ,
DanaK wrote:
Bill Waller Wrote:
On Fri, 06 May 2005 19:49:51 GMT, (Doug Miller)
wrote:
-
In article et, "Ralph
Mowery" wrote:-
"toller" wrote in message
...-
No such thing as 220v or 230v, only 240v; which some people insist on
calling almost anything. However, you are thinking of 208v, which is
two
legs of three phase; but since you don't have 3 phase, it really
doesn't
matter.
Over the years, the power companies have delivered power at various voltages..
originally there was 110/220, then 115/230, and now it's 120/240, although
sometimes it is really more like 125/250..
-
What voltage is 208 using two out of three legs of ? It is usually a
208
three phase system. YOu take two legs off that and get the nominal
110
volts.-
Wrong. 208V 3ph is 208V phase-to-phase and 120V phase-to-neutral.-
Except for Philadelphia Electric. I personally worked with a 240 3
phase
service that provide nominal 120v to ground (neutral) on two legs and
208v to
ground (neutral) on one leg. That leg was refereed to as the "high
leg". I
personally blew up some fluorescent lighting because I failed to check
which
leg I was using.
There are 2 general types of service in common use today, known as
Single phase, and 3 phase.
-----
Most single family residential will be single phase, where the secondary
side of the supply transformer consists of a single 240 volt winding, with
a grounded center tap for the neutral. This would be a 1 phase/3 wire service.
-----
There are two types of 3 phase wiring, known as WYE (Y), and Delta..
-----
In a 3 phase WYE connected service, the secondary side of the supply
transformer has 3 120 volt windings, 120 degrees apart, with one end of
each winding connected together, which is the grounded neutral.
The voltage from phase-neutral is 120 volts, phase-phase is 208 volts.
This type of supply is very common in locations where there are a lot of
single phase 120 volt loads. Phase colors are Black, Red, Blue.
This would be a 3 phase 120/208 WYE service.
------
In a 3 phase delta connected service, the secondary side of the supply
transformer has 3 (or 2) 240 volt windings, with one of them having a
center tap position. The windings are connected end-end in a delta
(triangle), with the bottom of the triangle being center tapped, for
the grounded neutral position.
The voltage from phase-phase is 240 volts, with the phases adjacent to
the center tap being 120 volts to neutral, and the high leg being 208 volts
to neutral. The center tapped leg looks exactly like a single phase service.
This type of supply is common in some types of industrial occupancies with
a large number of 3 phase motor loads, and a limited amount of 120 volt loads.
Phase colors are Black and Red for the center tapped side, and Orange or
Violet for the high leg (old standard was Orange, some jurisdictions now
require Violet.)
This would be a 3 phase 120/240 delta service.
A delta service can be delivered in several variations, such as 3 wire
(no neutral) for 240 volt 3 phase only, or as "open delta", where one of
the windings to the high leg is eliminated (generally for cost reasons..
it takes one less pole pig..) You find "open delta" in some places where
the requirement is for a limited amount of 3 phase power, as well as a
normal single phase 120/240 service, but mostly because the power company
dosen't want to spend the money for the third pole pig if they don't
absolutely have to...
-----
The actual transformer may have both types of connections, with delta
on the primary side, and WYE on the secondary.. Variations exist,
depending on the power company..
I have been told that the PECO scenario is a bit unusual.
It's not commonly seen in most newer installations, but it does exist..
____________________
Bill Waller
New Eagle, PA
Wow, quite a few people have posted to this thread all of a sudden. It
is interesting to read through them.
After checking the line to make sure the previous owner didn't use more
than one wire between the breaker box and the wall plug, which he'd been
known to do as old ranchers NEVER throw anything away, and consulting
with a few friends that are electricians, I've pretty much determined
that what happened was that one of the pair of 20 amp breakers that
this A/C unit was on has probably burned out internally. It's been
over a week and a half since I've had time to look at this but I plan
to replace them with a pair of 30 amp breakers like the other pair that
are in the box for the water heater.
VERY IMPORTANT
Before you replace the breakers, double check the wire size. It needs to
be at least 10awg for a 30 amp circuit. if it's 12awg, you need to stick
with 20 amp breakers.. If you have a 20 amp receptacle, you need to stick
with a 20 amp breaker.
Using a breaker that is rated for more then the wire can handle is asking
for trouble, since you can now overload the wire, and the breaker will not
protect it.
The voltage I get between the legs in this breaker box is 243vac. One
of the friends I consulted with said this was sufficient for the
application. Oh, and it IS all one wire between the breakers and the
plug. My friend did reccomend soldering the crimped ends onto the wire
to make a better connection, too. After that wrap the plug several
times in electrical tape which is what I usually do when installing or
otherwise working on wall plugs and switches.
I had to smile at one of the previous posts that replied to my
description of the house as being a "ranch house". Yew havta unnerstan
tha whut these ol ranchers dew on their "places" aint kwite az civilized
as yew peeple thut werk in the citiz'r used to. The closer you get to
thinking Looney Tunes and Rube Goldberg the closer you'll get to what's
been going on in these houses built any time from the 'teens to the
1950's. "Code" doesn't enter into the designer's mindset. I spent ten
years working in a hospital here in our city and I do know what looks
good and works right, in general, but I don't work on anything over
regular 120v house voltage unless I absolutely have to. That's why I'm
asking the questions here to see if I can pick something up. A
certified person would throw their hands up and run out of the house
screaming if they saw some of the things I've seen done. That's why
this old guy and I had less and less to talk about as time went on.
Anyway, I do appreciate the posts and will take with me all the
warnings and admonitions found here.
Thanks.
--
DanaK
--
-- Welcome My Son, Welcome To The Machine --
Bob Vaughan | techie @ tantivy.net |
| P.O. Box 19792, Stanford, Ca 94309 |
-- I am Me, I am only Me, And no one else is Me, What could be simpler? --