Matt Whiting wrote:

Read it again. I never said I was comparing split phase to 3 phase. I
said that "split" phase was the same as "two" phase with a 180 degree
phase separation.

Somewhere *I* got out of phase and misunderstood your post. My apologies.

--
Tony

wrote in message
Delta vs. Wye Power
Wye connected power has two different voltages available. The Phase to
Phase voltage is the main system voltage (typically 208 VAC or 480 VAC in
the United States). The Phase to Neutral voltage is also available, and is
typically used for small single phase loads (120 VAC or 277 VAC).


I never understood how the 277 adds up to 480.

Tony Miklos wrote:

wrote:

Tony, this is my first post on this subject, put it is hard not to
jump in
when you respond so negatively to a post you clearly didn't thoroughly
read.


Well I read it... more than once, but I guess my ADHD was kicking in and
I didn't understand the post. My appologies to Matt.

No sweat. I didn't take it negatively, I just figured you hadn't read
it the way I intended it so I asked you to read it again.

Matt

Edwin Pawlowski wrote:

wrote in message

Delta vs. Wye Power
Wye connected power has two different voltages available. The Phase to
Phase voltage is the main system voltage (typically 208 VAC or 480 VAC in
the United States). The Phase to Neutral voltage is also available, and is
typically used for small single phase loads (120 VAC or 277 VAC).



I never understood how the 277 adds up to 480.



Well it is really two 277 vectors that add up to 480 using vector
"addition." It's been a number of years since my EE degree so I haven't
done these calculations in many a moon, but the easiest way to see it is
to draw it out as a diagram. Then it is pretty clear what is going on.


Matt

Pointless to subject.

wrote:
Now, of course, three phase power can be either wye or delta
connected and there is a difference between these two kinds
of
three phase power. I'm sure you can explain the difference
to us
in simple terms and which kind is used for general power
distribution and why. When is the other kind used?

Yes, there is a difference, but it is pretty small ... one
more
conductor. :-)

Actually there is quite a bit more difference:

Delta and Wye Power
In the United States, there are two main types, or topologies,
of
three phase power. These are called Delta connected power, and
Wye
connected power. There are some similarities between Delta
connected
power and Wye connected power, and many differences. It is
important
to understand these two varieties of three phase power in
order to
properly specify power for your critical loads.

Delta Connected Power
Delta connected power is developed from three, independent
transformer or generator windings that are connected head to
toe.
There is no single point common to all phases. Delta power is
named
after the schematic resemblance of the windings to the Greek
letter
Delta.

A Delta Connected Source
Delta connected power is not commercially used in Europe.
Three-phase
European equipment requires Wye-connected power.

Wye Connected Power
Wye connected power is developed from three, independent
transformer
or generator windings that are connected at a common point,
called a
neutral or star point. Wye power is named after the schematic
resemblance of the windings to the Greek letter Wye ( Y ).

Delta vs. Wye Power
Wye connected power has two different voltages available. The
Phase
to Phase voltage is the main system voltage (typically 208 VAC
or
480 VAC in the United States). The Phase to Neutral voltage is
also
available, and is typically used for small single phase loads
(120
VAC or 277 VAC).

Delta connected power only has a single voltage level
available: the
Phase to Phase voltages. Other voltages can be obtained only
by
using step-up or step-down transformers.

Equipment designed to operate from Delta connected power, such
as air
conditioners or motors, can also operate from Wye connected
power
without a problem, since the Phase to Phase voltages are
available
in both systems. However, equipment that requires Wye
connected
power cannot operate from a Delta connected source. The Phase
to
Neutral voltages are not available. A special isolation
transformer,
designed to convert Delta to Wye, is used in this case.

Grounding of Delta and Wye Systems
It is common practice to ground the neutral, or center point
of a Wye
connected source. In most cases, this grounding is required by
the
United States' National Electric Code (NFPA-70). By grounding
a Wye
system, the voltages to ground are stabilized and controlled.
This
makes a system much less susceptible to impulses, ringing
transients, and faults that cause high voltages to ground. A
Delta
system is not required to be grounded, although some Delta
systems
are grounded. Usually these are grounded to one phase or to a
center
tap of one of the phases. This type of grounding is rare,
however.
In most cases, Delta systems are not grounded.

Ungrounded or Floating Sources
Ungrounded sources are often called Floating, because they
float with
reference to earth ground. System and wiring capacitance
determines
the voltage on any system point with reference to ground. As a
result of this, the Phase-Ground voltages on an ungrounded
source
are very susceptible to power quality disturbances.

The above is from http://www.teal.com/resources/an15.htm

Thanks Phil for your thorough commentary/analysis/etc. pertaining to the
O.P.'s (my) situation. (Sorry, though, for taking so long to respond.)

Amongst the other significant points you made, you wrote:

... then the J box filled with urethane roof sealant
(dries like tire rubber), then the water tight lid applied...
cement bulkheads poured at each side of the box so it couldnt
move or break at the conduit connections... well some guys
might call that safe enough for govt work. But it wouldn't
be legal. A short though would go directly to ground in
virtually all cases...

Okay, I can understand how pouring urethane roof sealant into the j-boxes
can not be expected to have legal status, if not only because it would not
appear to be "rational". But I'm not clear on, if for some oddball reason
someone were to try this, as to why you say (or seem to imply) _with
certainty_ that the urethane rubber could not be expected to electrically
isolate the connections in the j-box from each other and/or the outside
ground?

Thanks,

Guest987


"Phil Scott" wrote in message
. ..

"guest987" wrote in message
news:uWuyd.546239$Pl.492525@pd7tw1no...
"Duane Bozarth" wrote in message
...
[...]
Despite your best attempts, eventually there virtually surely will be
a leak and water will find a way in. Only underground-rated cable
should be used in an underground run despite the conduit. Normally
(unless there is an access tunnel in an industrial site, for example)
conduit is used to protect the cable from the above ground junction to
the required depth then the cable is laid in a trench. A protective
barrier is sometimes used over the cable, but not normally full run
buried in conduit. It's not an immediate danger, but eventually it
is
virtually certain to get water...

I see. So conduit was never meant to be a substitute for rubber-sheathed
underground-rated cable in the first place. And here people were
conveying
to me that rubber-sheathed underground-cable was something new in that it
didn't require conduit underground!

Close but no cigar just yet. You do need underground
rated cable for UG locations...but you do not have to use
conduit beyond a certain depth...usually 32"..

You can go shallower if you have a concrete pour over it, or
if it is in conduit of various sorts...the *minimum depths are
all called out in the NEC... but that doesnt mean a persons
particular job is safe or right, depends on how soft the
ground is in worst case conditions (muddy etc, with heavy
vehicles over the top).. salt water infiltration as we have at
low levels near the coast in many regions.

and of course no J Boxes underground at all (unless they are
in a manhole etc)....

Then there is fudging... say for instance you had an oversized
plastic J box underground with very carefully bolted
connections, then those painted with insulating sealant, say 3
or 4 coats, then that wrapped in rubber tape about 1/8"
thick... then the J box filled with urethane roof sealant
(dries like tire rubber), then the water tight lid applied...
cement bulkheads poured at each side of the box so it couldnt
move or break at the conduit connections... well some guys
might call that safe enough for govt work. But it wouldn't
be legal. A short though would go directly to ground in
virtually all cases...so there are much worse actual hazards
in the world... a red head could move in next door for
instance.

If it were in well drained ground, not prone to getting muddy
it might be a lot closer to OK.. If it were in muddy ground
with loads driving over it... it would not be ones slickest
move.

You have to scratch your ass and figure these things out....
sometimes I burp too. that helps.

The NEC code is part of the fire code... over heated wire,
shorts where they can cause a fire or go to ground though a
person are the primary issues... When you are underground
the fire hazard all but dissapears, same with the shock
hazard...unless someone digs into it etc.

In your case, and wire being relatively cheap, Id install
separate runs on your job... if the ground is muddy or
freezes, Id go deeper than the NEC requires, Id use schedule
80 pvc conduit regardless. put a few long radius glued bends
in it so it can expand and contract without stress, be sure
its in sand on the bottom and a few inches of sand on top,
40 years down the road the next owner is going to love you for
it. To make it easier on yourself, go one size larger on the
conduit than required as well....so the wire will pull easier.
Or you can bury the cable direct with no conduit below 32
inches... some people then lay redwood boards over the top and
yellow plastic marking tape so that if anyone digs there later
they will hit the boards and the tape as a warning. That
saves you the work of putting in the conduit and a long wire
pull. If the wire goes under a drive way or road you may
want to slide a schedule 80 pvc section of pipe over that part
of the run... bury it a little deeper there as well...and
maybe even pour some concrete over the top, 3" or so with a
little rebar in it. All that exceeds the NEC...but remember
the NEC and all of these codes are *minumum requirements and
are sure not best practice in all cases.


As I get older, I find that doing a job to world class
standards or better gives me a warm fuzzy feeling inside.
..its satisfying... Im also finding that it doesnt take much
more effort in most cases.






Phil Scott








So I chose conduit thinking that was
the 'tried-and-proven' standard method of laying underground
cable. I now
see I got it wrong. Well, the cable hasn't been tied in to
the power yet
(decided to wait until I can get the cash to hire a licensed
electrician for
the inside-of-house wiring --mainly for insurance reasons).
Guess I'll be
pulling out all the romex (as well as the
single-strand-wires) from the
conduit and replacing with underground-rated cable then. I
have junction
boxes underground too where power gets split to serve two
separate
destinations. (The rubber-sealed junction box covers, I had
reinforced with
silicone sealant --but come to think of it, silicone does in
time lose some
of its effectiveness), Guess I'll have to modify the cable
layout scheme,
in order to serve all of the separate power destinations,
without those
junctions...


Danger, fogey story...

Used to work w/ online coal analyzers at mines, prep
plants, etc. Had
location at mine in KY where they pulled the high voltage
signal power
cable (2.4kV) and had to go from the control shack where
the
electronics/computer were housed across a truck crossing
to the analyzer
mounted on the beltline. That installation was the mine's
responsibility, wasn't around when they did it. Installed
the unit,
brought it up, calibrated it, watched for a few hours,
went home...two
weeks later, get call...it's not operating. Drive up,
discover HV cable
shorted. Hood up the spare (we did require a spare be
pulled in the
specs), it worked, calibrated, watched, went home. Within
six months
second failed...turned out they had buried the cables in
conduit and it
filled w/ water. HV instrumentation cable isn't designed
for water
immersion and water also got inside the insulation.
Didn't help they
had pulled the cable through the conduit by hooking it to
a front end
loader when they couldn't pull it by hand , but that was
secondary...

They pulled with wire through with a front loader?! LOL!
Now that's a case
of applying too much 'brawn', as it were, and not enough
brain. Why didn't
they just use an approved lubricant and avoid stretching (if
not the risk of
breaking) the cable? (Don't try to answer. I'm sure you
wondered the same
thing.)


Thanks,

Guest987

guest987 posted for all of us....

Okay, I can understand how pouring urethane roof sealant into the j-boxes
can not be expected to have legal status, if not only because it would not
appear to be "rational". But I'm not clear on, if for some oddball reason
someone were to try this, as to why you say (or seem to imply) _with
certainty_ that the urethane rubber could not be expected to electrically
isolate the connections in the j-box from each other and/or the outside
ground?

Thanks,

Guest987

This dielectric strength has been tested & LISTED for what?

Could actually become conductive under certain circumstances.
--
Tekkie

"Tekkie" wrote in message
t...
[..]
This dielectric strength has been tested & LISTED for what?

Could actually become conductive under certain circumstances.

I see.

Now out of pure curiosity though, are there any such "pourable" materials or
products, which HAVE been tested and listed as safe and acceptable for such
a purpose (i.e. to immobilize, seal and electrically insulate
connectors...)?

Not that I care to try using such. It's just that I've had people claim
that epoxy (5-minute, common hardware-store variety??) can be safely used
this way. I used to think that made logical and intuitive sense. But now
that I'm becoming better 'edyucanated' g in this stuff (i.e. construction
wiring, etc...) I can see that, here, logic and intuition cannot be
permitted to substitute for referencing and following _only_ that which is
tested and approved practice.

Guest987

"guest987" wrote in message
news:Tr_Bd.681745$%k.351186@pd7tw2no...
Thanks Phil for your thorough commentary/analysis/etc.
pertaining to the
O.P.'s (my) situation. (Sorry, though, for taking so long
to respond.)

Amongst the other significant points you made, you wrote:

... then the J box filled with urethane roof sealant
(dries like tire rubber), then the water tight lid
applied...
cement bulkheads poured at each side of the box so it
couldnt
move or break at the conduit connections... well some
guys
might call that safe enough for govt work. But it
wouldn't
be legal. A short though would go directly to ground in
virtually all cases...

Okay, I can understand how pouring urethane roof sealant
into the j-boxes
can not be expected to have legal status, if not only
because it would not
appear to be "rational". But I'm not clear on, if for some
oddball reason
someone were to try this, as to why you say (or seem to
imply) _with
certainty_ that the urethane rubber could not be expected to
electrically
isolate the connections in the j-box from each other and/or
the outside
ground?

Thanks,

The urethane would **NOT*** be intended or used for
electrical insulation.. for that you rely bolted and rubber
taped and rubber liquid sealed connections....THEN...after
thats done you fill the box with the urethane roof sealant for
many reasons... a degree of water protection, and added
strength at the splice zone so that when the ground gets muddy
and someone drives over it with thier 20 ton cement truck the
wiring and splice will be more likely to stay in tact.

Phil Scott

Guest987


"Phil Scott" wrote in
message
. ..

"guest987" wrote in message
news:uWuyd.546239$Pl.492525@pd7tw1no...
"Duane Bozarth" wrote in message
...
[...]
Despite your best attempts, eventually there
virtually surely will be
a leak and water will find a way in. Only
underground-rated cable
should be used in an underground run despite the
conduit. Normally
(unless there is an access tunnel in an industrial
site, for example)
conduit is used to protect the cable from the above
ground junction to
the required depth then the cable is laid in a trench.
A protective
barrier is sometimes used over the cable, but not
normally full run
buried in conduit. It's not an immediate danger, but
eventually it
is
virtually certain to get water...

I see. So conduit was never meant to be a substitute for
rubber-sheathed
underground-rated cable in the first place. And here
people were
conveying
to me that rubber-sheathed underground-cable was
something new in that it
didn't require conduit underground!

Close but no cigar just yet. You do need underground
rated cable for UG locations...but you do not have to use
conduit beyond a certain depth...usually 32"..

You can go shallower if you have a concrete pour over it,
or
if it is in conduit of various sorts...the *minimum depths
are
all called out in the NEC... but that doesnt mean a
persons
particular job is safe or right, depends on how soft the
ground is in worst case conditions (muddy etc, with heavy
vehicles over the top).. salt water infiltration as we
have at
low levels near the coast in many regions.

and of course no J Boxes underground at all (unless they
are
in a manhole etc)....

Then there is fudging... say for instance you had an
oversized
plastic J box underground with very carefully bolted
connections, then those painted with insulating sealant,
say 3
or 4 coats, then that wrapped in rubber tape about 1/8"
thick... then the J box filled with urethane roof sealant
(dries like tire rubber), then the water tight lid
applied...
cement bulkheads poured at each side of the box so it
couldnt
move or break at the conduit connections... well some
guys
might call that safe enough for govt work. But it
wouldn't
be legal. A short though would go directly to ground in
virtually all cases...so there are much worse actual
hazards
in the world... a red head could move in next door for
instance.

If it were in well drained ground, not prone to getting
muddy
it might be a lot closer to OK.. If it were in muddy
ground
with loads driving over it... it would not be ones
slickest
move.

You have to scratch your ass and figure these things
out....
sometimes I burp too. that helps.

The NEC code is part of the fire code... over heated wire,
shorts where they can cause a fire or go to ground though
a
person are the primary issues... When you are
underground
the fire hazard all but dissapears, same with the shock
hazard...unless someone digs into it etc.

In your case, and wire being relatively cheap, Id install
separate runs on your job... if the ground is muddy or
freezes, Id go deeper than the NEC requires, Id use
schedule
80 pvc conduit regardless. put a few long radius glued
bends
in it so it can expand and contract without stress, be
sure
its in sand on the bottom and a few inches of sand on top,
40 years down the road the next owner is going to love you
for
it. To make it easier on yourself, go one size larger on
the
conduit than required as well....so the wire will pull
easier.
Or you can bury the cable direct with no conduit below 32
inches... some people then lay redwood boards over the top
and
yellow plastic marking tape so that if anyone digs there
later
they will hit the boards and the tape as a warning. That
saves you the work of putting in the conduit and a long
wire
pull. If the wire goes under a drive way or road you may
want to slide a schedule 80 pvc section of pipe over that
part
of the run... bury it a little deeper there as well...and
maybe even pour some concrete over the top, 3" or so with
a
little rebar in it. All that exceeds the NEC...but
remember
the NEC and all of these codes are *minumum requirements
and
are sure not best practice in all cases.


As I get older, I find that doing a job to world class
standards or better gives me a warm fuzzy feeling inside.
..its satisfying... Im also finding that it doesnt take
much
more effort in most cases.






Phil Scott








So I chose conduit thinking that was
the 'tried-and-proven' standard method of laying
underground
cable. I now
see I got it wrong. Well, the cable hasn't been tied in
to
the power yet
(decided to wait until I can get the cash to hire a
licensed
electrician for
the inside-of-house wiring --mainly for insurance
reasons).
Guess I'll be
pulling out all the romex (as well as the
single-strand-wires) from the
conduit and replacing with underground-rated cable then.
I
have junction
boxes underground too where power gets split to serve two
separate
destinations. (The rubber-sealed junction box covers, I
had
reinforced with
silicone sealant --but come to think of it, silicone does
in
time lose some
of its effectiveness), Guess I'll have to modify the
cable
layout scheme,
in order to serve all of the separate power destinations,
without those
junctions...


Danger, fogey story...

Used to work w/ online coal analyzers at mines, prep
plants, etc. Had
location at mine in KY where they pulled the high
voltage
signal power
cable (2.4kV) and had to go from the control shack
where
the
electronics/computer were housed across a truck
crossing
to the analyzer
mounted on the beltline. That installation was the
mine's
responsibility, wasn't around when they did it.
Installed
the unit,
brought it up, calibrated it, watched for a few hours,
went home...two
weeks later, get call...it's not operating. Drive up,
discover HV cable
shorted. Hood up the spare (we did require a spare be
pulled in the
specs), it worked, calibrated, watched, went home.
Within
six months
second failed...turned out they had buried the cables
in
conduit and it
filled w/ water. HV instrumentation cable isn't
designed
for water
immersion and water also got inside the insulation.
Didn't help they
had pulled the cable through the conduit by hooking it
to
a front end
loader when they couldn't pull it by hand , but that
was
secondary...

They pulled with wire through with a front loader?! LOL!
Now that's a case
of applying too much 'brawn', as it were, and not enough
brain. Why didn't
they just use an approved lubricant and avoid stretching
(if
not the risk of
breaking) the cable? (Don't try to answer. I'm sure you
wondered the same
thing.)


Thanks,

Guest987

"Tekkie" wrote in message
t...
guest987 posted for all of us....

Okay, I can understand how pouring urethane roof sealant
into the j-boxes
can not be expected to have legal status, if not only
because it would not
appear to be "rational". But I'm not clear on, if for
some oddball reason
someone were to try this, as to why you say (or seem to
imply) _with
certainty_ that the urethane rubber could not be expected
to electrically
isolate the connections in the j-box from each other
and/or the outside
ground?

Thanks,

Guest987

This dielectric strength has been tested & LISTED for what?

Could actually become conductive under certain
circumstances.

You dont use the urethane roof sealant to make the splice...
you use it to fill the splice box after you have made a proper
electrically insulative splice.. to provide a degree of
additional water proofing and strength in the area.

Phil Scott

--
Tekkie

"guest987" wrote in message
news:_I8Cd.677115$Pl.617815@pd7tw1no...

"Tekkie" wrote in message
t...
[..]
This dielectric strength has been tested & LISTED for
what?

Could actually become conductive under certain
circumstances.

I see.

Now out of pure curiosity though, are there any such
"pourable" materials or
products, which HAVE been tested and listed as safe and
acceptable for such
a purpose (i.e. to immobilize, seal and electrically
insulate
connectors...)?


Yes there are and you should have used them to seal and
electrically insulate the splice....I recommended the urthene
to FILL THE BOX ONLY and for a water sealant...to keep water
from collecting in the empty splice box.



Not that I care to try using such. It's just that I've had
people claim
that epoxy (5-minute, common hardware-store variety??) can
be safely used
this way. I used to think that made logical and intuitive
sense. But now
that I'm becoming better 'edyucanated' g in this stuff
(i.e. construction
wiring, etc...) I can see that, here, logic and intuition
cannot be
permitted to substitute for referencing and following _only_
that which is
tested and approved practice.


sigh....





Guest987

If you are going to pull individual wires through conduit, the hard
part is to pull the wires through without nicking the insulalation. If
you nick the insulaiton at all, even a little, the moisture that will
be inside the conduit will eventually corrode the wire and it will fail
open. For this reason, if its a do it yourself job, I think you are
better off use direct burial romex inside an oversized unsealed PVC
pipe for physical protection. Maybe even drill holes in the PVC to let
the water out.

Mark

Mark posted for all of us....


If you are going to pull individual wires through conduit, the hard
part is to pull the wires through without nicking the insulalation. If
you nick the insulaiton at all, even a little, the moisture that will
be inside the conduit will eventually corrode the wire and it will fail

Whatttttttttt?
open. For this reason, if its a do it yourself job, I think you are
better off use direct burial romex inside an oversized unsealed PVC
pipe for physical protection. Maybe even drill holes in the PVC to let
the water out.

Let the water in! And weaken the pipe.

Mark


Hey, where did you get this from???
--
Tekkie