History:

In a ealier topic, I wrote of my old house, built in 1952 + remodeled
by someone who knew even less than I. It has no grounds and is a
general mess, I think even according to code back then -people tell
me the electrician and the building inspector were "friends."

Thirty years ago, when I bought this house, the person inspecting it as
well as myself saw the standard, three prong, grounded outlets and
thought all was okay; but he didn't check to make sure they worked
and I was too young to know to tell him to. After all, he was the
inspector.

It wasn't until sometime later; when I found a few, two slot,
non-grounded outlets, I became suspicious. And my suspicions are
correct. Someone replaced nearly all the outlets with three prong,
polarized, grounded ones, but no ground to connect them to and no way
to fish a ground to them.

Here's Today's problems and a few questions:

I got a laptop computer for Christmas. It uses an AC to DC adapter
(transformer) to get power and recharge the computer's batteries.

Unlike most modern electronics, this one has a non-polarized socket for
the charger and the power cord is non-polarized, non-grounded too.
Neither is there any kind of marking, such as a white stripe along the
cord that lets me know which is the hot/neutral side. From what I've
read, a white stripe usually indicates it is the polarized side (the
neutral) and goes into the longer slot on the wall socket. The longer
slot is always neutral. Is that right?

The instructions say, plug the charger into the computer and then that
into the wall socket.
When I did it, there was an arc from the wall socket's left slot. I
thought that's strange. (This is one of the three prong, polarized,
grounded (but not really) sockets.)

I left it plugged in for a day or so. I unplugged it. Later, when I
plugged it back in, without paying attention to the orientation of the
plug, there was no spark. I thought, "strange," again. So, I flipped
the power cord plug over, plugged it in that way and sure enough, a
spark from the left slot of the wall socket. --bright blue and snappy.

Obviously, the left (tall) slot of the wall socket is hot (which I
think is backwards according to code?). And with no white stripe on
the power cord that plugs into the transformer, then no polarized
socket on the computer: two round holes, instead of a square and round,
I can't tell which is hot/neutral and what should go where, but I
sure didn't like the arc at the wall socket.

Looking at the power cord's plug, the tip of the prong that got the
zap, is a bit black and melted.
Of course, I don't want to destroy the very expensive computer.

1) Does it matter which way the power cord goes into the outlet?
With nothing polarized, I don't know what to do. Or does it matter?

Spark, no spark? destroy my computer or is it okay, no matter which
way it goes into the AC?


2) Further checking the wall sockets, looking at them from the front
(ground down), I find some take a polarized plug's neutral prong, (I
think that the wide one), fits into the wall socket's tall, left
slot; for others wall sockets though, the tall slot is on the right. .


I assume that the wall sockets that take it on the right are turned
upside down, so no harm done-as long as it's wired correctly.
(I'm off to Lowes to get an outlet checker.)


3) I tested a three prong, polarized, grounded (but not really), duplex
socket with my VOM (battery powered) for voltage. I pushed one probe
into the short slot, the other into the long (left) slot.

When I put the probe into the left slot-Pow! A nice, blue arc from
the tip of it into the slot.
I tried it again and the same thing happened. I switched the
probes-no arc. I was surprised by that since I thought with AC, as
long as the VOM is set to AC, it doesn't matter which way the +-
probes go.

Since the arcing distracted me, I failed to get the voltage. I tried
my VOM once more.

This time, when I put the probe into the left slot there was a big
flash. My VOM went dead-is dead-- and so is the wall outlet. Now,
I have to go by a new VOM, new wall socket. Funny that the fuse
didn't blow in the VOM nor did a circuit breaker trip.

Ideas on what may have happened and how do I fix it?

Most importantly though, any damage being done to the computer?

--more threads on my old house wiring, coming.

Bob T

Breakers or fuses? If breakers how old? If it's the original stuff,
it's too old and you need a new electrical panel. And most likely some
more circuits.
Is the wire run in armored cable? If so then you do have a ground and
can most likely just use that as your ground.

3) I tested a three prong, polarized, grounded (but not really), duplex
socket with my VOM (battery powered) for voltage. I pushed one probe
into the short slot, the other into the long (left) slot.

When I put the probe into the left slot-Pow! A nice, blue arc from
the tip of it into the slot.
I tried it again and the same thing happened. I switched the
probes-no arc. I was surprised by that since I thought with AC, as
long as the VOM is set to AC, it doesn't matter which way the +-
probes go.



Sounds like you have your hands full............thats for sure. If
using a VOM.......be sure to set the dial to the desired range first
and be sure that the probes are in the correct meter slots for checking
AC. The different settings have different impedances. But you are
correct......you should be able to put the probes in either slot.

What you are stating makes no sense at all to me.......I am not an
Electrician....but an Engineer in a Hospital setting. What do the other
outlets do, read?..the same thing....spark?? Sounds like maybe you
should rewire the whole house properly with new breaker box and get it
over with. If the probes and/or computer plug melted....then the fuse
or breaker should have tripped.......no? Thats alot of current to melt
metal!!

You should run the proper wire yourself to save a few bucks, then have
the electrician hook it all up to the new box. Definetly worth it in
your case. Sounds like a future house fire is in the making here.

stars1234 wrote:

Deleted some of the history.


Unlike most modern electronics, this one has a non-polarized socket for
the charger and the power cord is non-polarized, non-grounded too.
Neither is there any kind of marking, such as a white stripe along the
cord that lets me know which is the hot/neutral side. From what I've
read, a white stripe usually indicates it is the polarized side (the
neutral) and goes into the longer slot on the wall socket. The longer
slot is always neutral. Is that right?

Correct. However, a polarized connection is not necessary for the
charger. It does not know the difference.



The instructions say, plug the charger into the computer and then that
into the wall socket.
When I did it, there was an arc from the wall socket's left slot. I
thought that's strange. (This is one of the three prong, polarized,
grounded (but not really) sockets.)

Now that worries me.

I left it plugged in for a day or so. I unplugged it. Later, when I
plugged it back in, without paying attention to the orientation of the
plug, there was no spark. I thought, "strange," again. So, I flipped
the power cord plug over, plugged it in that way and sure enough, a
spark from the left slot of the wall socket. --bright blue and snappy.
Obviously, the left (tall) slot of the wall socket is hot (which I
think is backwards according to code?). And with no white stripe on
the power cord that plugs into the transformer, then no polarized
socket on the computer: two round holes, instead of a square and round,
I can't tell which is hot/neutral and what should go where, but I
sure didn't like the arc at the wall socket.

Arcs should not happen under any condition. The presence of an arc has
no relationship as to which line is hot. That is unless you are
shorting a ground to the wires.

Looking at the power cord's plug, the tip of the prong that got the
zap, is a bit black and melted.
Of course, I don't want to destroy the very expensive computer.


My thoughts are that there is something wrong with the socket. Perhaps
a loose wire.




1) Does it matter which way the power cord goes into the outlet?
With nothing polarized, I don't know what to do. Or does it matter?

No. It should not make any difference.


Spark, no spark? destroy my computer or is it okay, no matter which
way it goes into the AC?


2) Further checking the wall sockets, looking at them from the front
(ground down), I find some take a polarized plug's neutral prong, (I
think that the wide one), fits into the wall socket's tall, left
slot; for others wall sockets though, the tall slot is on the right. .


Orientation is not important. What is important is how the sockets were
wired. If your wire has the proper color code the hot should be black
and the neutral should be white. Black connected to the narrow slot and
white to the wide.



I assume that the wall sockets that take it on the right are turned
upside down, so no harm done-as long as it's wired correctly.
(I'm off to Lowes to get an outlet checker.)


Correct. No problem


3) I tested a three prong, polarized, grounded (but not really), duplex
socket with my VOM (battery powered) for voltage. I pushed one probe
into the short slot, the other into the long (left) slot.

When I put the probe into the left slot-Pow! A nice, blue arc from
the tip of it into the slot.

Not a good test. You should not be drawing any current to speak of
through your meter. That is unless you have it on a current measurement
setting. Then I would expect you would blow something.


I tried it again and the same thing happened. I switched the
probes-no arc. I was surprised by that since I thought with AC, as
long as the VOM is set to AC, it doesn't matter which way the +-
probes go.

Since the arcing distracted me, I failed to get the voltage. I tried
my VOM once more.

This time, when I put the probe into the left slot there was a big
flash. My VOM went dead-is dead-- and so is the wall outlet. Now,
I have to go by a new VOM, new wall socket. Funny that the fuse
didn't blow in the VOM nor did a circuit breaker trip.

Again I have to guess that there was something wrong inside the VOM.
You blew the line open before the circuit breaker had time to trip.


Ideas on what may have happened and how do I fix it?

Most importantly though, any damage being done to the computer?

I would hold off until I find out what the voltages are doing.

I think you must have had a short inside the VOM all along.

To verify which line is hot and which is neutral I would us a jumper to
get the negative lead of my vom hooked to a ground such as a water pipe.
Then you should read 110 on the hot line. If you are using a high
impedance meter you might see some voltage on the neutral but not very high.

Rich256 wrote:
stars1234 wrote:

Deleted some of the history.

....

Arcs should not happen under any condition. The presence of an arc has
no relationship as to which line is hot. That is unless you are
shorting a ground to the wires.

Could be charging blocking cap and is causing some. Or perhaps the
reversing polarity is discharging a cap when into the neutral which is
at ground.

....
3) I tested a three prong, polarized, grounded (but not really), duplex
socket with my VOM (battery powered) for voltage. I pushed one probe
into the short slot, the other into the long (left) slot.

When I put the probe into the left slot-Pow! A nice, blue arc from
the tip of it into the slot.

Not a good test. You should not be drawing any current to speak of
through your meter. That is unless you have it on a current measurement
setting. Then I would expect you would blow something.
....

This time, when I put the probe into the left slot there was a big
flash. My VOM went dead-is dead-- and so is the wall outlet. Now,
I have to go by a new VOM, new wall socket. Funny that the fuse
didn't blow in the VOM nor did a circuit breaker trip.

Are you sure it didn't blow the VOM fuse? Normally they would only be
a fraction of an amp. I'd double check it.

My bet is w/ the likelihood you were either on a continuity or current
or input range by accident.

Except for the floating ground introduced w/ the use of a grounding
outlet w/ a two-wire service, there really isn't anything so
bad-sounding on the house here except it sounds like there might be
crossed neutrals and hots if the receptacles weren't installed
correctly (or at least consistently). I'd do a certainty check on that
for all of them and I'd do it visually rather than relying on an
inexpensive tester -- I've seen cases where some weren't terribly
reliable.

dpb wrote:

Could be charging blocking cap and is causing some. Or perhaps the
reversing polarity is discharging a cap when into the neutral which is
at ground.
Doubtful. The caps are so small. Getting sparks when plugging in a VOM
means something really wrong. Either a short in the meter or on
something like the 10 amp scale.

My bet is w/ the likelihood you were either on a continuity or current
or input range by accident.
Agree




Except for the floating ground introduced w/ the use of a grounding
outlet w/ a two-wire service, there really isn't anything so
bad-sounding on the house here except it sounds like there might be
crossed neutrals and hots if the receptacles weren't installed
correctly (or at least consistently). I'd do a certainty check on that
for all of them and I'd do it visually rather than relying on an
inexpensive tester -- I've seen cases where some weren't terribly
reliable.

And even if they are crossed it should make no difference for most
appliances. Danger is that some things such as lamps could end up with
the outside being hot. But even they are insulated. In the old days
you could end up with a radio chassis being hot. No polarization at all
in those days either.

stars1234 wrote:

History:

In a ealier topic, I wrote of my old house, built in 1952 + remodeled
by someone who knew even less than I. It has no grounds and is a
general mess, I think even according to code back then -people tell
me the electrician and the building inspector were "friends."

Thirty years ago, when I bought this house, the person inspecting it as
well as myself saw the standard, three prong, grounded outlets and
thought all was okay; but he didn't check to make sure they worked
and I was too young to know to tell him to. After all, he was the
inspector.

It wasn't until sometime later; when I found a few, two slot,
non-grounded outlets, I became suspicious. And my suspicions are
correct. Someone replaced nearly all the outlets with three prong,
polarized, grounded ones, but no ground to connect them to and no way
to fish a ground to them.

Here's Today's problems and a few questions:

I got a laptop computer for Christmas. It uses an AC to DC adapter
(transformer) to get power and recharge the computer's batteries.

Unlike most modern electronics, this one has a non-polarized socket for
the charger and the power cord is non-polarized, non-grounded too.
Neither is there any kind of marking, such as a white stripe along the
cord that lets me know which is the hot/neutral side. From what I've
read, a white stripe usually indicates it is the polarized side (the
neutral) and goes into the longer slot on the wall socket. The longer
slot is always neutral. Is that right?

The instructions say, plug the charger into the computer and then that
into the wall socket.
When I did it, there was an arc from the wall socket's left slot. I
thought that's strange. (This is one of the three prong, polarized,
grounded (but not really) sockets.)

I left it plugged in for a day or so. I unplugged it. Later, when I
plugged it back in, without paying attention to the orientation of the
plug, there was no spark. I thought, "strange," again. So, I flipped
the power cord plug over, plugged it in that way and sure enough, a
spark from the left slot of the wall socket. --bright blue and snappy.

Obviously, the left (tall) slot of the wall socket is hot (which I
think is backwards according to code?). And with no white stripe on
the power cord that plugs into the transformer, then no polarized
socket on the computer: two round holes, instead of a square and round,
I can't tell which is hot/neutral and what should go where, but I
sure didn't like the arc at the wall socket.

Looking at the power cord's plug, the tip of the prong that got the
zap, is a bit black and melted.
Of course, I don't want to destroy the very expensive computer.

1) Does it matter which way the power cord goes into the outlet?
With nothing polarized, I don't know what to do. Or does it matter?

Spark, no spark? destroy my computer or is it okay, no matter which
way it goes into the AC?

2) Further checking the wall sockets, looking at them from the front
(ground down), I find some take a polarized plug's neutral prong, (I
think that the wide one), fits into the wall socket's tall, left
slot; for others wall sockets though, the tall slot is on the right. .

I assume that the wall sockets that take it on the right are turned
upside down, so no harm done-as long as it's wired correctly.
(I'm off to Lowes to get an outlet checker.)

3) I tested a three prong, polarized, grounded (but not really), duplex
socket with my VOM (battery powered) for voltage. I pushed one probe
into the short slot, the other into the long (left) slot.

When I put the probe into the left slot-Pow! A nice, blue arc from
the tip of it into the slot.
I tried it again and the same thing happened. I switched the
probes-no arc. I was surprised by that since I thought with AC, as
long as the VOM is set to AC, it doesn't matter which way the +-
probes go.

Since the arcing distracted me, I failed to get the voltage. I tried
my VOM once more.

This time, when I put the probe into the left slot there was a big
flash. My VOM went dead-is dead-- and so is the wall outlet. Now,
I have to go by a new VOM, new wall socket. Funny that the fuse
didn't blow in the VOM nor did a circuit breaker trip.

Ideas on what may have happened and how do I fix it?

Most importantly though, any damage being done to the computer?

--more threads on my old house wiring, coming.

Bob T

Others have addressed the meter issues and the probable outlet issues so
I'll stick with just the computer issue.

A laptop "line lump" power adapter does not care at all which of it's
input leads is hot and which is neutral. Further, most any new laptop
line lump is auto ranging and should list something like ~100-240V
50/60Hz as it's input rating.

You may well get a small spark when plugging the power adapter in as
it's going to have an initial surge on power up (regardless of whether
the laptop is on or connected since the power adapter is always on.

If the adapter is indeed auto ranging as noted, there is nothing you
house wiring can do to damage it since the worst your wiring can do is
provide 240V to a 120V outlet which is bad for many items, but the
laptop power adapter would happily auto range to and operate just fine.

Pete C.

"stars1234" wrote in message
Here's Today's problems and a few questions:

I got a laptop computer for Christmas. It uses an AC to DC adapter
(transformer) to get power and recharge the computer's batteries.

Unlike most modern electronics, this one has a non-polarized socket for
the charger and the power cord is non-polarized, non-grounded too.
Neither is there any kind of marking, such as a white stripe along the
cord that lets me know which is the hot/neutral side. From what I've
read, a white stripe usually indicates it is the polarized side (the
neutral) and goes into the longer slot on the wall socket. The longer
slot is always neutral. Is that right?

The instructions say, plug the charger into the computer and then that
into the wall socket.
When I did it, there was an arc from the wall socket's left slot. I
thought that's strange. (This is one of the three prong, polarized,
grounded (but not really) sockets.)

I left it plugged in for a day or so. I unplugged it. Later, when I
plugged it back in, without paying attention to the orientation of the
plug, there was no spark. I thought, "strange," again. So, I flipped
the power cord plug over, plugged it in that way and sure enough, a
spark from the left slot of the wall socket. --bright blue and snappy.

Obviously, the left (tall) slot of the wall socket is hot (which I
think is backwards according to code?). And with no white stripe on
the power cord that plugs into the transformer, then no polarized
socket on the computer: two round holes, instead of a square and round,
I can't tell which is hot/neutral and what should go where, but I
sure didn't like the arc at the wall socket.

Looking at the power cord's plug, the tip of the prong that got the
zap, is a bit black and melted.
Of course, I don't want to destroy the very expensive computer.

1) Does it matter which way the power cord goes into the outlet?
With nothing polarized, I don't know what to do. Or does it matter?

The side that sparks has nothing to do with which side is "hot". It
merely indicates which side makes contact last, or breaks contact first.
You could try replacing the outlet with a new "spec" grade outlet.
Avoid the cheap outlets.

Bob

Here's Today's problems and a few questions:

I got a laptop computer for Christmas. It uses an AC to DC adapter
(transformer) to get power and recharge the computer's batteries.

Unlike most modern electronics, this one has a non-polarized socket for
the charger and the power cord is non-polarized, non-grounded too.
Neither is there any kind of marking, such as a white stripe along the
cord that lets me know which is the hot/neutral side. From what I've
read, a white stripe usually indicates it is the polarized side (the
neutral) and goes into the longer slot on the wall socket. The longer
slot is always neutral. Is that right?

The instructions say, plug the charger into the computer and then that
into the wall socket.
When I did it, there was an arc from the wall socket's left slot. I
thought that's strange. (This is one of the three prong, polarized,
grounded (but not really) sockets.)

I left it plugged in for a day or so. I unplugged it. Later, when I
plugged it back in, without paying attention to the orientation of the
plug, there was no spark. I thought, "strange," again. So, I flipped
the power cord plug over, plugged it in that way and sure enough, a
spark from the left slot of the wall socket. --bright blue and snappy.

The power adapter doesn't care how you plug in the cord and it is
transformer isolated from the computer. To DC a Transformer is a short and
for a moment to AC it's a short but only for a moment. It's not uncommon to
have a small arc when plugging in a computer transformer, no matter the
orientation of the plug. This is especially true when the computers battery
is discharged, that is the spark will be more profound, if there is one.


Obviously, the left (tall) slot of the wall socket is hot (which I
think is backwards according to code?). And with no white stripe on
the power cord that plugs into the transformer, then no polarized
socket on the computer: two round holes, instead of a square and round,
I can't tell which is hot/neutral and what should go where, but I
sure didn't like the arc at the wall socket.

You can't be sure of this just by observation. Where you do have grounds
they and the neutral should be at the same potential, talking about 110VAC
now.

Looking at the power cord's plug, the tip of the prong that got the
zap, is a bit black and melted.

That concerns me a bit, not because it's showing black from an arc but
melted? Melted does concern me a bit. Could be you are plugging it in very
very slowly over and over but I doubt that would even cause that.


Of course, I don't want to destroy the very expensive computer.

1) Does it matter which way the power cord goes into the outlet?
With nothing polarized, I don't know what to do. Or does it matter?

Spark, no spark? destroy my computer or is it okay, no matter which
way it goes into the AC?

Shouldn't matter due to the isolation of the transformer and power adapter.



2) Further checking the wall sockets, looking at them from the front
(ground down), I find some take a polarized plug's neutral prong, (I
think that the wide one), fits into the wall socket's tall, left
slot; for others wall sockets though, the tall slot is on the right. .

If the grounding lug is on the bottom then the longer slot (the Neutral)
should always be on the left and the shorter slot (HOT) always on the right.
If a ground is hooked up correctly, extending back to the panel box, then
with a volt meter you should measure 110 VAC from the Short slot to the
longer slot and also 110VAC from the short slot to the grounding slot which
is the hole or almost round hole. From the Longer Slot to the Ground hole
there should be negligible voltage almost zero.


I assume that the wall sockets that take it on the right are turned
upside down, so no harm done-as long as it's wired correctly.
(I'm off to Lowes to get an outlet checker.)

If it's a outlet without a ground plug hole that might be the case.


3) I tested a three prong, polarized, grounded (but not really), duplex
socket with my VOM (battery powered) for voltage. I pushed one probe
into the short slot, the other into the long (left) slot.

When I put the probe into the left slot-Pow! A nice, blue arc from
the tip of it into the slot.
I tried it again and the same thing happened. I switched the
probes-no arc. I was surprised by that since I thought with AC, as
long as the VOM is set to AC, it doesn't matter which way the +-
probes go.

Any Volt Ohm meter when measuring Voltage, with the leads correctly inserted
in a working and non-faulty meter should never cause an arc or pop or any
sound. If the leads however are plugged into the slots for measuring AMP's
(Current) then you are putting a SHORT CIRCUIT (which I feel you did) on the
meter. Don't worry the reason you didn't have it happen again is that you
BLEW the fuse on the inside of the meter. You have to have the probes from
V - Voltage to the Ground lead of the volt meter. Some meters may use the
same two holes or connections for every reading (current, volts, & ohms) but
that is very dangerous. When you place your meter in AMP's or current
measuring Amps then you have a direct short across those leads and that will
cause any outlet to Arc and a loud pop until the meter blows or the breaker
trips. My bets are the meter frys or the fuse blows. Better check that
meter's fuse in the current lead. If only two slots your meter most likely
isn't working very well now.

Since the arcing distracted me, I failed to get the voltage. I tried
my VOM once more.

This time, when I put the probe into the left slot there was a big
flash. My VOM went dead-is dead-- and so is the wall outlet. Now,
I have to go by a new VOM, new wall socket. Funny that the fuse
didn't blow in the VOM nor did a circuit breaker trip.

I'm surprised also -- Still wonder what terminals you had the probes plugged
into and if you had the meter on Amps or Voltage.


Ideas on what may have happened and how do I fix it?

Most importantly though, any damage being done to the computer?

Find a working meter, perform Voltage checks with the leads in the correct
plug locations on the meter and if you have 110VAC on the outlet the
computer's power adapter shouldn't care.

Mind you mine, like everyone else's is just an opinion based on each of our
experiences so you have to make your own and best decisions because it's
your computer and you are the one there and know best what's going on and
what you did.



--more threads on my old house wiring, coming.

Bob T

One other thought or caution ... Make sure someone didn't wire the outlet
for 220 Volts .. If so that could definitely cause your computer and power
adapter problems .. Aka do I see smoke?





On 12/28/06 6:00 PM, in article , "Gary
KW4Z" wrote:


Here's Today's problems and a few questions:

I got a laptop computer for Christmas. It uses an AC to DC adapter
(transformer) to get power and recharge the computer's batteries.

Unlike most modern electronics, this one has a non-polarized socket for
the charger and the power cord is non-polarized, non-grounded too.
Neither is there any kind of marking, such as a white stripe along the
cord that lets me know which is the hot/neutral side. From what I've
read, a white stripe usually indicates it is the polarized side (the
neutral) and goes into the longer slot on the wall socket. The longer
slot is always neutral. Is that right?

The instructions say, plug the charger into the computer and then that
into the wall socket.
When I did it, there was an arc from the wall socket's left slot. I
thought that's strange. (This is one of the three prong, polarized,
grounded (but not really) sockets.)

I left it plugged in for a day or so. I unplugged it. Later, when I
plugged it back in, without paying attention to the orientation of the
plug, there was no spark. I thought, "strange," again. So, I flipped
the power cord plug over, plugged it in that way and sure enough, a
spark from the left slot of the wall socket. --bright blue and snappy.

The power adapter doesn't care how you plug in the cord and it is
transformer isolated from the computer. To DC a Transformer is a short and
for a moment to AC it's a short but only for a moment. It's not uncommon to
have a small arc when plugging in a computer transformer, no matter the
orientation of the plug. This is especially true when the computers battery
is discharged, that is the spark will be more profound, if there is one.


Obviously, the left (tall) slot of the wall socket is hot (which I
think is backwards according to code?). And with no white stripe on
the power cord that plugs into the transformer, then no polarized
socket on the computer: two round holes, instead of a square and round,
I can't tell which is hot/neutral and what should go where, but I
sure didn't like the arc at the wall socket.

You can't be sure of this just by observation. Where you do have grounds
they and the neutral should be at the same potential, talking about 110VAC
now.

Looking at the power cord's plug, the tip of the prong that got the
zap, is a bit black and melted.

That concerns me a bit, not because it's showing black from an arc but
melted? Melted does concern me a bit. Could be you are plugging it in very
very slowly over and over but I doubt that would even cause that.


Of course, I don't want to destroy the very expensive computer.

1) Does it matter which way the power cord goes into the outlet?
With nothing polarized, I don't know what to do. Or does it matter?

Spark, no spark? destroy my computer or is it okay, no matter which
way it goes into the AC?

Shouldn't matter due to the isolation of the transformer and power adapter.



2) Further checking the wall sockets, looking at them from the front
(ground down), I find some take a polarized plug's neutral prong, (I
think that the wide one), fits into the wall socket's tall, left
slot; for others wall sockets though, the tall slot is on the right. .

If the grounding lug is on the bottom then the longer slot (the Neutral)
should always be on the left and the shorter slot (HOT) always on the right.
If a ground is hooked up correctly, extending back to the panel box, then
with a volt meter you should measure 110 VAC from the Short slot to the
longer slot and also 110VAC from the short slot to the grounding slot which
is the hole or almost round hole. From the Longer Slot to the Ground hole
there should be negligible voltage almost zero.


I assume that the wall sockets that take it on the right are turned
upside down, so no harm done-as long as it's wired correctly.
(I'm off to Lowes to get an outlet checker.)

If it's a outlet without a ground plug hole that might be the case.


3) I tested a three prong, polarized, grounded (but not really), duplex
socket with my VOM (battery powered) for voltage. I pushed one probe
into the short slot, the other into the long (left) slot.

When I put the probe into the left slot-Pow! A nice, blue arc from
the tip of it into the slot.
I tried it again and the same thing happened. I switched the
probes-no arc. I was surprised by that since I thought with AC, as
long as the VOM is set to AC, it doesn't matter which way the +-
probes go.

Any Volt Ohm meter when measuring Voltage, with the leads correctly inserted
in a working and non-faulty meter should never cause an arc or pop or any
sound. If the leads however are plugged into the slots for measuring AMP's
(Current) then you are putting a SHORT CIRCUIT (which I feel you did) on the
meter. Don't worry the reason you didn't have it happen again is that you
BLEW the fuse on the inside of the meter. You have to have the probes from
V - Voltage to the Ground lead of the volt meter. Some meters may use the
same two holes or connections for every reading (current, volts, & ohms) but
that is very dangerous. When you place your meter in AMP's or current
measuring Amps then you have a direct short across those leads and that will
cause any outlet to Arc and a loud pop until the meter blows or the breaker
trips. My bets are the meter frys or the fuse blows. Better check that
meter's fuse in the current lead. If only two slots your meter most likely
isn't working very well now.

Since the arcing distracted me, I failed to get the voltage. I tried
my VOM once more.

This time, when I put the probe into the left slot there was a big
flash. My VOM went dead-is dead-- and so is the wall outlet. Now,
I have to go by a new VOM, new wall socket. Funny that the fuse
didn't blow in the VOM nor did a circuit breaker trip.

I'm surprised also -- Still wonder what terminals you had the probes plugged
into and if you had the meter on Amps or Voltage.


Ideas on what may have happened and how do I fix it?

Most importantly though, any damage being done to the computer?

Find a working meter, perform Voltage checks with the leads in the correct
plug locations on the meter and if you have 110VAC on the outlet the
computer's power adapter shouldn't care.

Mind you mine, like everyone else's is just an opinion based on each of our
experiences so you have to make your own and best decisions because it's
your computer and you are the one there and know best what's going on and
what you did.



--more threads on my old house wiring, coming.

Bob T

Gary KW4Z wrote:


Here's Today's problems and a few questions:

I got a laptop computer for Christmas. It uses an AC to DC adapter
(transformer) to get power and recharge the computer's batteries.

Unlike most modern electronics, this one has a non-polarized socket for
the charger and the power cord is non-polarized, non-grounded too.
Neither is there any kind of marking, such as a white stripe along the
cord that lets me know which is the hot/neutral side. From what I've
read, a white stripe usually indicates it is the polarized side (the
neutral) and goes into the longer slot on the wall socket. The longer
slot is always neutral. Is that right?

The instructions say, plug the charger into the computer and then that
into the wall socket.
When I did it, there was an arc from the wall socket's left slot. I
thought that's strange. (This is one of the three prong, polarized,
grounded (but not really) sockets.)

I left it plugged in for a day or so. I unplugged it. Later, when I
plugged it back in, without paying attention to the orientation of the
plug, there was no spark. I thought, "strange," again. So, I flipped
the power cord plug over, plugged it in that way and sure enough, a
spark from the left slot of the wall socket. --bright blue and snappy.

The power adapter doesn't care how you plug in the cord and it is
transformer isolated from the computer. To DC a Transformer is a short
and
for a moment to AC it's a short but only for a moment. It's not uncommon
to have a small arc when plugging in a computer transformer, no matter the
orientation of the plug. This is especially true when the computers
battery is discharged, that is the spark will be more profound, if there
is one.



The one thing your missing though is laptop supplies are not usually a
transformer, they are typically a switched power supply otherwise they
would be much larger and heavier. A typical switching power supply will
switch the hot side on and off thousands of times a second and very the
pulse width to get the proper output voltage. I oversimplified but I hope
you get the idea that since there is no transformer the characteristics
will be different.

On 28 Dec 2006 12:20:50 -0800, "stars1234"
wrote:

Ideas on what may have happened and how do I fix it?

Most importantly though, any damage being done to the computer?


I can only suggest a computer solution. Unless you have some
exceptional warranty that covers damage you may get (from 50's
wiring). I would advise something like:

http://www.apc.com/products/family/index.cfm?id=23

In a network environment once; one saved me during a "brown out". It
protected from the drop and surge in power.

Good Luck.
--
Oren

"Well, it doesn't happen all the time, but when it happens, it happens constantly."