Was called to look at an electrical problem. I looked at the panel that
seemed to be the culprit, determined it to be a 240 v. 3-phase
(probably) panel with a few breakers that were causing problems. One
side of one of the power lugs was completely burned off, and the breaker
on the other lug was making sizzling sounds. Turned it off pronto.

The panel has 3 big fat wires coming into it. Measured between all of
them: 240 volts between all 3, which makes me think it's 3-phase (3
legs, equal voltage).

But here's the weird thing: there are some 120-volt outlets apparently
attached to this panel that function correctly. When I turned some of
the breakers off, the outlets lost power, so I assume that they're
directly powered from this panel.

How can this be? How do you get 120 volts from 240? (No big fat
transformers visible anywhere.) What am I missing here?

In case anyone's wondering, no, I don't mess with 3-phase power or any
other kind of heavy-duty commercial/industrial stuff. My customer's
reaction was "I'll call a licensed electrician", which would have been
my advice. It appears the entire panel needs replaced.

I'm just curious about this situation.


--
Personally, I like Vista, but I probably won't use it. I like it
because it generates considerable business for me in consulting and
upgrades. As long as there is hardware and software out there that
doesn't work, I stay in business. Incidentally, my company motto is
"If this stuff worked, you wouldn't need me".

- lifted from sci.electronics.repair

On Mon, 09 Feb 2009 17:28:31 -0800, David Nebenzahl
wrote:

Was called to look at an electrical problem. I looked at the panel that
seemed to be the culprit, determined it to be a 240 v. 3-phase
(probably) panel with a few breakers that were causing problems. One
side of one of the power lugs was completely burned off, and the breaker
on the other lug was making sizzling sounds. Turned it off pronto.

The panel has 3 big fat wires coming into it. Measured between all of
them: 240 volts between all 3, which makes me think it's 3-phase (3
legs, equal voltage).

But here's the weird thing: there are some 120-volt outlets apparently
attached to this panel that function correctly. When I turned some of
the breakers off, the outlets lost power, so I assume that they're
directly powered from this panel.

How can this be? How do you get 120 volts from 240? (No big fat
transformers visible anywhere.) What am I missing here?

In case anyone's wondering, no, I don't mess with 3-phase power or any
other kind of heavy-duty commercial/industrial stuff. My customer's
reaction was "I'll call a licensed electrician", which would have been
my advice. It appears the entire panel needs replaced.

I'm just curious about this situation.

Just curious. What kind of work do you do?
Why were you called to look at an electrical problem?

David Nebenzahl wrote:

Was called to look at an electrical problem. I looked at the panel that
seemed to be the culprit, determined it to be a 240 v. 3-phase
(probably) panel with a few breakers that were causing problems. One
side of one of the power lugs was completely burned off, and the breaker
on the other lug was making sizzling sounds. Turned it off pronto.

The panel has 3 big fat wires coming into it. Measured between all of
them: 240 volts between all 3, which makes me think it's 3-phase (3
legs, equal voltage).

But here's the weird thing: there are some 120-volt outlets apparently
attached to this panel that function correctly. When I turned some of
the breakers off, the outlets lost power, so I assume that they're
directly powered from this panel.

How can this be? How do you get 120 volts from 240? (No big fat
transformers visible anywhere.) What am I missing here?

In case anyone's wondering, no, I don't mess with 3-phase power or any
other kind of heavy-duty commercial/industrial stuff. My customer's
reaction was "I'll call a licensed electrician", which would have been
my advice. It appears the entire panel needs replaced.

I'm just curious about this situation.


If you read 240V and not 208V it's most likely a three phase delta
configuration. To get single phase 120V service out of it one of the
three distribution transformers in the three phase configuration has
it's secondary center tapped to provide a neutral that gives 120V
relative to each of that transformers poles. Since this transformer
represents one side of the delta configuration and is connected to two
of the three phase legs, that third phase leg is *not* 120V relative to
the neutral and is normally color coded orange to identify it. The third
leg is ~208V relative to the neutral and is typically called the "wild
leg" or some less PC terms. I'm sure a 'net search on "wild leg" and
"delta" will turn up some diagrams.

"David Nebenzahl" wrote in message
.com...
Was called to look at an electrical problem. I looked at the panel that
seemed to be the culprit, determined it to be a 240 v. 3-phase (probably)
panel with a few breakers that were causing problems. One side of one of
the power lugs was completely burned off, and the breaker on the other lug
was making sizzling sounds. Turned it off pronto.

The panel has 3 big fat wires coming into it. Measured between all of
them: 240 volts between all 3, which makes me think it's 3-phase (3 legs,
equal voltage).

But here's the weird thing: there are some 120-volt outlets apparently
attached to this panel that function correctly. When I turned some of the
breakers off, the outlets lost power, so I assume that they're directly
powered from this panel.

How can this be? How do you get 120 volts from 240? (No big fat
transformers visible anywhere.) What am I missing here?

In case anyone's wondering, no, I don't mess with 3-phase power or any
other kind of heavy-duty commercial/industrial stuff. My customer's
reaction was "I'll call a licensed electrician", which would have been my
advice. It appears the entire panel needs replaced.

I'm just curious about this situation.


*On a three phase delta service you would get 120 volts between two of the
legs and ground or a neutral. The third leg would have a much higher
voltage to ground and should be identified with orange tape if there was a
neutral in this panel.

If there was no neutral available in this panel then there should be a
transformer somewhere to provide the 120 volts.

Are you sure that the voltage was 240? It could be a three phase wye
service which would have four conductors and the voltage would be 120/208.

On 2/9/2009 5:38 PM metspitzer spake thus:

Just curious. What kind of work do you do?
Why were you called to look at an electrical problem?

None of your beeswax.

--
Personally, I like Vista, but I probably won't use it. I like it
because it generates considerable business for me in consulting and
upgrades. As long as there is hardware and software out there that
doesn't work, I stay in business. Incidentally, my company motto is
"If this stuff worked, you wouldn't need me".

- lifted from sci.electronics.repair

"David Nebenzahl" wrote in message
.com...
Was called to look at an electrical problem. I looked at the panel that
seemed to be the culprit, determined it to be a 240 v. 3-phase (probably)
panel with a few breakers that were causing problems. One side of one of
the power lugs was completely burned off, and the breaker on the other lug
was making sizzling sounds. Turned it off pronto.

The panel has 3 big fat wires coming into it. Measured between all of
them: 240 volts between all 3, which makes me think it's 3-phase (3 legs,
equal voltage).

But here's the weird thing: there are some 120-volt outlets apparently
attached to this panel that function correctly. When I turned some of the
breakers off, the outlets lost power, so I assume that they're directly
powered from this panel.

How can this be? How do you get 120 volts from 240? (No big fat
transformers visible anywhere.) What am I missing here?

In case anyone's wondering, no, I don't mess with 3-phase power or any
other kind of heavy-duty commercial/industrial stuff. My customer's
reaction was "I'll call a licensed electrician", which would have been my
advice. It appears the entire panel needs replaced.

I'm just curious about this situation.


--
Personally, I like Vista, but I probably won't use it. I like it
because it generates considerable business for me in consulting and
upgrades. As long as there is hardware and software out there that
doesn't work, I stay in business. Incidentally, my company motto is
"If this stuff worked, you wouldn't need me".

- lifted from sci.electronics.repair

What you missed is the neutral. And it's probably lucky that you didn't
start messing with what appears to be a Delta service.

On 2/9/2009 5:38 PM Pete C. spake thus:

David Nebenzahl wrote:

But here's the weird thing: there are some 120-volt outlets apparently
attached to this panel that function correctly. When I turned some of
the breakers off, the outlets lost power, so I assume that they're
directly powered from this panel.

How can this be? How do you get 120 volts from 240? (No big fat
transformers visible anywhere.) What am I missing here?

In case anyone's wondering, no, I don't mess with 3-phase power or any
other kind of heavy-duty commercial/industrial stuff. My customer's
reaction was "I'll call a licensed electrician", which would have been
my advice. It appears the entire panel needs replaced.

I'm just curious about this situation.

If you read 240V and not 208V it's most likely a three phase delta
configuration. To get single phase 120V service out of it one of the
three distribution transformers in the three phase configuration has
it's secondary center tapped to provide a neutral that gives 120V
relative to each of that transformers poles. Since this transformer
represents one side of the delta configuration and is connected to two
of the three phase legs, that third phase leg is *not* 120V relative to
the neutral and is normally color coded orange to identify it. The third
leg is ~208V relative to the neutral and is typically called the "wild
leg" or some less PC terms. I'm sure a 'net search on "wild leg" and
"delta" will turn up some diagrams.

Yes, it was 240 volts. Thanks for the explanation, by the way.

Found a diagram that shows a delta configuration with a wild leg. Makes
sense.

But that panel only has 3 big fat wires coming into it, so apparently
there's no neutral (or no center-tap) connection. Is it possible that
this wire was upstream of this panel and connected elsewhere?

Not going to lose any sleep over this; just curious.


--
Personally, I like Vista, but I probably won't use it. I like it
because it generates considerable business for me in consulting and
upgrades. As long as there is hardware and software out there that
doesn't work, I stay in business. Incidentally, my company motto is
"If this stuff worked, you wouldn't need me".

- lifted from sci.electronics.repair

David Nebenzahl wrote:
On 2/9/2009 5:38 PM Pete C. spake thus:

David Nebenzahl wrote:

But here's the weird thing: there are some 120-volt outlets apparently
attached to this panel that function correctly. When I turned some of
the breakers off, the outlets lost power, so I assume that they're
directly powered from this panel.

How can this be? How do you get 120 volts from 240? (No big fat
transformers visible anywhere.) What am I missing here?

In case anyone's wondering, no, I don't mess with 3-phase power or any
other kind of heavy-duty commercial/industrial stuff. My customer's
reaction was "I'll call a licensed electrician", which would have been
my advice. It appears the entire panel needs replaced.

I'm just curious about this situation.

If you read 240V and not 208V it's most likely a three phase delta
configuration. To get single phase 120V service out of it one of the
three distribution transformers in the three phase configuration has
it's secondary center tapped to provide a neutral that gives 120V
relative to each of that transformers poles. Since this transformer
represents one side of the delta configuration and is connected to two
of the three phase legs, that third phase leg is *not* 120V relative to
the neutral and is normally color coded orange to identify it. The third
leg is ~208V relative to the neutral and is typically called the "wild
leg" or some less PC terms. I'm sure a 'net search on "wild leg" and
"delta" will turn up some diagrams.

Yes, it was 240 volts. Thanks for the explanation, by the way.

Found a diagram that shows a delta configuration with a wild leg. Makes
sense.

But that panel only has 3 big fat wires coming into it, so apparently
there's no neutral (or no center-tap) connection. Is it possible that
this wire was upstream of this panel and connected elsewhere?

Not going to lose any sleep over this; just curious.




The outlets receiving 120V may be fed via one of the 240V
breakers which is connected to an "autotransformer" or to
an isolation 240/120V xfmr. In that case, the "derived"
Neutral would not appear at the panel and the service would
be plain Jane 240V Delta.

Jim

David Nebenzahl wrote:

On 2/9/2009 5:38 PM Pete C. spake thus:

David Nebenzahl wrote:

But here's the weird thing: there are some 120-volt outlets apparently
attached to this panel that function correctly. When I turned some of
the breakers off, the outlets lost power, so I assume that they're
directly powered from this panel.

How can this be? How do you get 120 volts from 240? (No big fat
transformers visible anywhere.) What am I missing here?

In case anyone's wondering, no, I don't mess with 3-phase power or any
other kind of heavy-duty commercial/industrial stuff. My customer's
reaction was "I'll call a licensed electrician", which would have been
my advice. It appears the entire panel needs replaced.

I'm just curious about this situation.

If you read 240V and not 208V it's most likely a three phase delta
configuration. To get single phase 120V service out of it one of the
three distribution transformers in the three phase configuration has
it's secondary center tapped to provide a neutral that gives 120V
relative to each of that transformers poles. Since this transformer
represents one side of the delta configuration and is connected to two
of the three phase legs, that third phase leg is *not* 120V relative to
the neutral and is normally color coded orange to identify it. The third
leg is ~208V relative to the neutral and is typically called the "wild
leg" or some less PC terms. I'm sure a 'net search on "wild leg" and
"delta" will turn up some diagrams.

Yes, it was 240 volts. Thanks for the explanation, by the way.

Found a diagram that shows a delta configuration with a wild leg. Makes
sense.

But that panel only has 3 big fat wires coming into it, so apparently
there's no neutral (or no center-tap) connection. Is it possible that
this wire was upstream of this panel and connected elsewhere?

Not going to lose any sleep over this; just curious.

Quite common for a building with delta service to have separate three
phase only and 120/240 single phase panels to help avoid confusion and
mistakes. Three hot legs and ground in the three phase panel and the
neural, two correct hot legs and ground in the single phase panel.

If you were turning off breakers in the three phase panel and 120V loads
were going off things could be a bit of a mess as is often the case with
older industrial services. 240V delta is mostly used in industrial
occupancies with big three phase loads as opposed to general commercial
where 208/120V wye service is preferred due to the large number of 120V
loads.

David Nebenzahl wrote:
Was called to look at an electrical problem. I looked at the panel that
seemed to be the culprit, determined it to be a 240 v. 3-phase
(probably) panel with a few breakers that were causing problems. One
side of one of the power lugs was completely burned off, and the breaker
on the other lug was making sizzling sounds. Turned it off pronto.

The panel has 3 big fat wires coming into it. Measured between all of
them: 240 volts between all 3, which makes me think it's 3-phase (3
legs, equal voltage).

But here's the weird thing: there are some 120-volt outlets apparently
attached to this panel that function correctly. When I turned some of
the breakers off, the outlets lost power, so I assume that they're
directly powered from this panel.

How can this be? How do you get 120 volts from 240? (No big fat
transformers visible anywhere.) What am I missing here?

In case anyone's wondering, no, I don't mess with 3-phase power or any
other kind of heavy-duty commercial/industrial stuff. My customer's
reaction was "I'll call a licensed electrician", which would have been
my advice. It appears the entire panel needs replaced.

I'm just curious about this situation.



Sounds like its standard 240V panel with an open neutral.
When the neutral is open you get full voltage readings on the neutral
from the other leg via any loads that are attached and turned on.
The loads may be turned on but not functioning. ie a filament of the
light will be dark. Since no, or very little, current is flowing then
100% of the voltage is passed through the filament when read with a volt
meter.

Remember there is no voltage drop through a resistor where there is no
current flowing... so with a meter you will measure the same voltage on
both ends of that resistor.

Open neutrals do strange things Some lights will be dim, others very
bright and other will appear to be off depending on what load are
attached to each leg.

Kevin

Kevin Ricks wrote:

David Nebenzahl wrote:
Was called to look at an electrical problem. I looked at the panel that
seemed to be the culprit, determined it to be a 240 v. 3-phase
(probably) panel with a few breakers that were causing problems. One
side of one of the power lugs was completely burned off, and the breaker
on the other lug was making sizzling sounds. Turned it off pronto.

The panel has 3 big fat wires coming into it. Measured between all of
them: 240 volts between all 3, which makes me think it's 3-phase (3
legs, equal voltage).

But here's the weird thing: there are some 120-volt outlets apparently
attached to this panel that function correctly. When I turned some of
the breakers off, the outlets lost power, so I assume that they're
directly powered from this panel.

How can this be? How do you get 120 volts from 240? (No big fat
transformers visible anywhere.) What am I missing here?

In case anyone's wondering, no, I don't mess with 3-phase power or any
other kind of heavy-duty commercial/industrial stuff. My customer's
reaction was "I'll call a licensed electrician", which would have been
my advice. It appears the entire panel needs replaced.

I'm just curious about this situation.



Sounds like its standard 240V panel with an open neutral.
When the neutral is open you get full voltage readings on the neutral
from the other leg via any loads that are attached and turned on.
The loads may be turned on but not functioning. ie a filament of the
light will be dark. Since no, or very little, current is flowing then
100% of the voltage is passed through the filament when read with a volt
meter.

Remember there is no voltage drop through a resistor where there is no
current flowing... so with a meter you will measure the same voltage on
both ends of that resistor.

Open neutrals do strange things Some lights will be dim, others very
bright and other will appear to be off depending on what load are
attached to each leg.

Kevin

That's a possibility. The presence of any three pole breakers in the
panel would be a tip off that it's three phase. Either way, with
sizzling breakers and burned off lugs it needs serious attention and
likely replacement.

On Feb 9, 7:53 pm, David Nebenzahl wrote:
On 2/9/2009 5:38 PM metspitzer spake thus:

Just curious. What kind of work do you do?
Why were you called to look at an electrical problem?

None of your beeswax.

Don't you know software guys can fix anything?

With a snippy answer like this, we can only leave to imagine
that you're stealing power from some where. And that you're
up to no good.

--
Christopher A. Young
Learn more about Jesus
www.lds.org
..


"David Nebenzahl" wrote in message
.com...
On 2/9/2009 5:38 PM metspitzer spake thus:

Just curious. What kind of work do you do?
Why were you called to look at an electrical problem?

None of your beeswax.

I have a few questions, and a few ideas. However, you didn't
provide enough information in your post. And, I doubt you'll
answer any questions. Seeing as how you're being snippy with
folks, today.

--
Christopher A. Young
Learn more about Jesus
www.lds.org
..


"David Nebenzahl" wrote in message
.com...
Was called to look at an electrical problem. I looked at the
panel that
seemed to be the culprit, determined it to be a 240 v.
3-phase
(probably) panel with a few breakers that were causing
problems. One
side of one of the power lugs was completely burned off, and
the breaker
on the other lug was making sizzling sounds. Turned it off
pronto.

The panel has 3 big fat wires coming into it. Measured
between all of
them: 240 volts between all 3, which makes me think it's
3-phase (3
legs, equal voltage).

But here's the weird thing: there are some 120-volt outlets
apparently
attached to this panel that function correctly. When I
turned some of
the breakers off, the outlets lost power, so I assume that
they're
directly powered from this panel.

How can this be? How do you get 120 volts from 240? (No big
fat
transformers visible anywhere.) What am I missing here?

In case anyone's wondering, no, I don't mess with 3-phase
power or any
other kind of heavy-duty commercial/industrial stuff. My
customer's
reaction was "I'll call a licensed electrician", which would
have been
my advice. It appears the entire panel needs replaced.

I'm just curious about this situation.

On 2/9/2009 7:57 PM Stormin Mormon spake thus:

I have a few questions, and a few ideas. However, you didn't
provide enough information in your post. And, I doubt you'll
answer any questions. Seeing as how you're being snippy with
folks, today.

I think this one's been pretty well answered, Stormin. Check the other
posts.


--
Personally, I like Vista, but I probably won't use it. I like it
because it generates considerable business for me in consulting and
upgrades. As long as there is hardware and software out there that
doesn't work, I stay in business. Incidentally, my company motto is
"If this stuff worked, you wouldn't need me".

- lifted from sci.electronics.repair

On 2/9/2009 7:55 PM Stormin Mormon spake thus:

With a snippy answer like this, we can only leave to imagine
that you're stealing power from some where. And that you're
up to no good.

Yeah. I'm stealing power and selling it out-of-state. Big bucks.


--
Personally, I like Vista, but I probably won't use it. I like it
because it generates considerable business for me in consulting and
upgrades. As long as there is hardware and software out there that
doesn't work, I stay in business. Incidentally, my company motto is
"If this stuff worked, you wouldn't need me".

- lifted from sci.electronics.repair

You better be using an old truck to haul all that electric.
The Feds might confiscate the truck that you're using to
haul the electricity. Interestate thef, and all.

--
Christopher A. Young
Learn more about Jesus
www.lds.org
..


"David Nebenzahl" wrote in message
.com...
On 2/9/2009 7:55 PM Stormin Mormon spake thus:

With a snippy answer like this, we can only leave to
imagine
that you're stealing power from some where. And that
you're
up to no good.

Yeah. I'm stealing power and selling it out-of-state. Big
bucks.

On 2/10/2009 5:37 AM Stormin Mormon spake thus:

You better be using an old truck to haul all that electric.
The Feds might confiscate the truck that you're using to
haul the electricity. Interestate thef, and all.

Nah, I just use a bunch of 55 gallon drums.


--
Personally, I like Vista, but I probably won't use it. I like it
because it generates considerable business for me in consulting and
upgrades. As long as there is hardware and software out there that
doesn't work, I stay in business. Incidentally, my company motto is
"If this stuff worked, you wouldn't need me".

- lifted from sci.electronics.repair