Just in case this guy was serious:

1) What makes you think DC is cheaper if nobody offers it for sale?
2) Don't blame the people you spoke to on the phone for not knowing
about DC--odds are you were the first person to make this request in
the last 90 years--if ever.
3) I used to work in a NY office building with DC; since that wouldn't
run air-conditioning, they gave us salt tablets. My college dorm was
DC, too, and we had to buy converters to run our stereo and
refrigerator--with the amount of electronics in today's dorms, we
would have been driven crazy.

wrote:
On Tue, 6 Apr 2010 12:03:40 -0700 (PDT),
wrote:

Just in case this guy was serious:

1) What makes you think DC is cheaper if nobody offers it for sale?
2) Don't blame the people you spoke to on the phone for not knowing
about DC--odds are you were the first person to make this request in
the last 90 years--if ever.
3) I used to work in a NY office building with DC; since that wouldn't
run air-conditioning, they gave us salt tablets. My college dorm was
DC, too, and we had to buy converters to run our stereo and
refrigerator--with the amount of electronics in today's dorms, we
would have been driven crazy.

Even though it's not practical to distribute DC because of the wire
thickness needed as well as losses, in some ways I can see where
there can be some confusion. With DC, the power goes directly to the
device. For example, in a flashlight, the DC batteries send the
electric power directly to the lightbulb (thus the word DIRECT).

With AC, the power goes thru the bulb and is returned to the source
minus what was lost from heating the filament in the bulb (mostly the
loss is from heat). Knowing that, I always wondered just how much of
the electric is returned to the power company in an AC system. Since
that returned power has gone thru our electric meter, does the power
company sell the same electric twice or more times? Maybe there is
some truth in DC being cheaper to the consumer, (not taking into
consideration the much higher costs to distribute it). I have always
wondered what happened to that returned power in an AC system.

Hi,
You sound so SIMPLISTIC! Think basic Ohm's law again and law of energy
conservation. Power(energy) never gets lost for one.

As for safety, I have never experienced a 120volt DC shock. Has
anyone? Is it less painful or harmful than 120v AC? I have no
idea.... I know that a 12VDC car battery can not shock a person, or
at least it's not noticable.

On 4/6/2010 3:37 PM, wrote:
On Tue, 6 Apr 2010 12:03:40 -0700 (PDT),
wrote:


As for safety, I have never experienced a 120volt DC shock. Has
anyone? Is it less painful or harmful than 120v AC? I have no
idea.... I know that a 12VDC car battery can not shock a person, or
at least it's not noticable.



The great danger from power company AC (more so in the Northern Hemisphere than
in the rest of the world) is the 60 Hz frequency - which is close enough to your
heart muscle's pacemaker to throw you into ventricular fibrillation (which is
lethal unless defibrillated with a DC shock). Outside of the Northern
Hemisphere they tend to use 50 Hz, which is somewhat less dangerous because it
is less likely than 60 Hz to ruin your entire day!

AC shocks produce a sensation of intense vibration without a lot of motion in
your muscles, which can make it very easy to continue to hold on to whatever you
have touched that is conducting the shock. DC shocks produce a violent
contraction in the muscles, which if you are lucky will cause you to jerk away
from the conducting object. They both can be quite painful, depending upon the
amount of current and the duration of the shocks.

Don't believe that you cannot receive a really painful and/or injurious shock
from a car battery. It depends upon your resistance (are you full of
perspiration at the time you receive the shock or is your skin entirely intact
and dry). Car batteries can deliver a really nasty high amperage shock if the
resistance in the shock path is low and you can get really nasty burns from the
heat that can be generated.

The damage from a shock is related to the energy (watts) delivered which is the
product of the voltage and the current. The lower the resistance, the higher
the current (given a constant voltage).

"Tony Hwang" wrote in message
...
wrote:
On Tue, 6 Apr 2010 12:03:40 -0700 (PDT),
wrote:

Just in case this guy was serious:

1) What makes you think DC is cheaper if nobody offers it for sale?
2) Don't blame the people you spoke to on the phone for not knowing
about DC--odds are you were the first person to make this request in
the last 90 years--if ever.
3) I used to work in a NY office building with DC; since that wouldn't
run air-conditioning, they gave us salt tablets. My college dorm was
DC, too, and we had to buy converters to run our stereo and
refrigerator--with the amount of electronics in today's dorms, we
would have been driven crazy.

Even though it's not practical to distribute DC because of the wire
thickness needed as well as losses, in some ways I can see where
there can be some confusion. With DC, the power goes directly to the
device. For example, in a flashlight, the DC batteries send the
electric power directly to the lightbulb (thus the word DIRECT).

With AC, the power goes thru the bulb and is returned to the source
minus what was lost from heating the filament in the bulb (mostly the
loss is from heat). Knowing that, I always wondered just how much of
the electric is returned to the power company in an AC system. Since
that returned power has gone thru our electric meter, does the power
company sell the same electric twice or more times? Maybe there is
some truth in DC being cheaper to the consumer, (not taking into
consideration the much higher costs to distribute it). I have always
wondered what happened to that returned power in an AC system.

Hi,
You sound so SIMPLISTIC! Think basic Ohm's law again and law of energy
conservation. Power(energy) never gets lost for one.

Tony, did you BUY your EE degree, thru the mail?
The laws of thermo notwithstanding, USEFUL power (ie, high-quality
low-entropy power) is ALWAYS lost/degraded. To, uhhh, heat.....

The OP (or Heffron) is in a sense right, in that the *electrons* are proly
recycled, but they have to be re-energized.
Ergo Ohm's Law --- Voltage *drop*, in joules per coulomb of electrons.

AC is proly easier to produce from a generator pov, as DC requires a split
commutator, which wears.
And still, the DC is probably not constant, but more like rectified, ie,
sinusoidal "humps", and would still need filtering, etc. Or so I
believe....

The main advantage of AC is the step up/step down-ability with transformers.
Ergo, the efficiency of hi-voltage lines over distance, low voltage in
neighborhoods.

HOWEVER,
I read recently that research into high-voltage transmission was
suggesting that very high voltage DC transmission was more efficient that
AC -- proly due to lack of capacitance/inductive effects et al, or some
other wizardry -- and that with the advent of solid state inverters,
transforming DC to AC would be less problematic, rendering DC transmission
ultimately viable.

As far as which to use in the house, proly doesn't really matter. But, good
luck running 99% of modern appliances/electronics off DC. Which, prior to
inverters, would have been near-impossible for low-voltage circuits.

As to which is safer, AC certainly arcs less, and DC would seem to more
readily polarize tissue, thus more readily rendering muscles catatonic, esp.
the heart. I subscribe to this opinion.
AC *can* do the same, from first-hand experience, but DC certainly does it
better.

HOWEVER,
I have read medical opinion to the opposite, that AC is the more
dangerous, altho with no real physiologic reasoning. I suspect they are
wrong.

Most electricians consider DC far more troublesome.

Along these lines, http://en.wikipedia.org/wiki/Defibrillation seems to
suggest that DC (or damped sinusoidal, or slow biphasic) is more effective
and requires lower voltages to be effective.
Which suggests that DC is indeed more physiologically potent.

True AC in defibrillation, esp. at 60 hz, is likely hit and miss,
phase-wise. Whereas DC defibrillation would either be "all hit" or "all
miss".... ergo the biphasic deal.

All in all, the OP is a troll -- and an idiot.
Bob-tx's 4/4 post on electricity was far funnier.

NYC provided DC to various buildings, mostly for their elevator service, I
believe.
I think someone posted here that this may have been discontinued altogether,
but in the 80's, you bumped into it every now and then.

Mebbe the OP can find one of these old buildings.....

And, with all due respect, J Heffron needs to read a book on applied
electricity.... goodgawd....
Hey, Tony, mebbe you and Heffron can chip in on an electricity book -- mebbe
one without calculus....
--
EA




As for safety, I have never experienced a 120volt DC shock. Has
anyone? Is it less painful or harmful than 120v AC? I have no
idea.... I know that a 12VDC car battery can not shock a person, or
at least it's not noticable.

On Tue, 06 Apr 2010 14:37:11 -0500, wrote:

On Tue, 6 Apr 2010 12:03:40 -0700 (PDT), Ivan
wrote:

Just in case this guy was serious:

1) What makes you think DC is cheaper if nobody offers it for sale?
2) Don't blame the people you spoke to on the phone for not knowing
about DC--odds are you were the first person to make this request in
the last 90 years--if ever.
3) I used to work in a NY office building with DC; since that wouldn't
run air-conditioning, they gave us salt tablets. My college dorm was
DC, too, and we had to buy converters to run our stereo and
refrigerator--with the amount of electronics in today's dorms, we
would have been driven crazy.

Even though it's not practical to distribute DC because of the wire
thickness needed as well as losses, in some ways I can see where
there can be some confusion. With DC, the power goes directly to the
device. For example, in a flashlight, the DC batteries send the
electric power directly to the lightbulb (thus the word DIRECT).

With AC, the power goes thru the bulb and is returned to the source
minus what was lost from heating the filament in the bulb (mostly the
loss is from heat). Knowing that, I always wondered just how much of
the electric is returned to the power company in an AC system. Since
that returned power has gone thru our electric meter, does the power
company sell the same electric twice or more times? Maybe there is
some truth in DC being cheaper to the consumer, (not taking into
consideration the much higher costs to distribute it). I have always
wondered what happened to that returned power in an AC system.

As for safety, I have never experienced a 120volt DC shock. Has
anyone? Is it less painful or harmful than 120v AC? I have no
idea.... I know that a 12VDC car battery can not shock a person, or
at least it's not noticable.

Boy - you want to learn about electricity and electrical theory.
DC and AC work EXACTLY the same, except AC reverses irself 50 or 60
times a second. The power is ALL used in the load, either AC or DC.

The big problem with DC is switching it. On AC the current crosses
zero twice in each cycle - so 100 or 120 times a second. This quenches
the arc - in DC the current is constant and switchgear flashover is
always a problem

As for safety - AC and DC are relatively equal as far as shocks are
concerned - if 12 volts DC does not give a shock, 12 volts AC won't
either. The only difference is a DC shock is a "single hit" while
AC is a "buzzzz" WHich is more dangerous? Since AC hurts more, I'd
say DC is the more dangerous - easier to ignore??????

On Tue, 06 Apr 2010 17:25:22 -0500, wrote:



What comes from a car's ignition coil? I got knocked on my ass from
that a few times. Damn that hurts !!!!

In excess of 60,000 volts AC

Don't believe that you cannot receive a really painful and/or injurious shock
from a car battery. It depends upon your resistance (are you full of
perspiration at the time you receive the shock or is your skin entirely intact
and dry). Car batteries can deliver a really nasty high amperage shock if the
resistance in the shock path is low and you can get really nasty burns from the
heat that can be generated.

Guess I have been lucky. I never have felt a thing from touching a
live 12v wire in a car.


It takes an extremely unlikely set of circumstances to lower the
resistance of the body enough to let a 12 volt battery pass much
current through that body. Basically it will involve mucous membranes
or extreme saturation.

12 volts AC will give you a "tingle" long before you will feel DC and
you can get a tingle on your toungue from a half dead 9 volt
battery

The damage from a shock is related to the energy (watts) delivered which is the
product of the voltage and the current. The lower the resistance, the higher
the current (given a constant voltage).


Actually it is strictly the CURRENT - but it takes voltage to push
that current, and if the resistance is low enough that 2 volts can
cause the lethal current to flow, 2 volts COULD kill you.

I'm not saying there is a likely scenario where 2 volts could cause
that current to flow - it's all Ohm's Law.


If the resistance is high enough that it takes 90 volts to force a
lethal current through the body, 50 volts might be painfull, but
wouldn't kill.

wrote in message
...
On Tue, 06 Apr 2010 17:25:22 -0500, wrote:



What comes from a car's ignition coil? I got knocked on my ass from
that a few times. Damn that hurts !!!!

In excess of 60,000 volts AC

Don't believe that you cannot receive a really painful and/or injurious
shock
from a car battery. It depends upon your resistance (are you full of
perspiration at the time you receive the shock or is your skin entirely
intact
and dry). Car batteries can deliver a really nasty high amperage shock
if the
resistance in the shock path is low and you can get really nasty burns
from the
heat that can be generated.

Guess I have been lucky. I never have felt a thing from touching a
live 12v wire in a car.

If you ever have the opportunity to go swimming and boating in the salt
water of the ocean, climb out of the water and while nice and wet lay your
arm across the terminals of the 12 vdc battery used for starting the engine.
A different and unique experience!

On Tue, 06 Apr 2010 22:07:33 -0400, clare wrote:
As for safety - AC and DC are relatively equal as far as shocks are
concerned - if 12 volts DC does not give a shock, 12 volts AC won't
either. The only difference is a DC shock is a "single hit" while AC
is a "buzzzz" WHich is more dangerous? Since AC hurts more, I'd say DC
is the more dangerous - easier to ignore??????

Lots of old railroad engineers have told me that DC was far worse because
it can make muscles contract - and then you can't let go of whatever it
is that's causing the shock. Whether there's truth in that, I'm not
sure...

I don't know how many 240V AC shocks I've had over the years when I lived
in the UK, but certainly quite a few. I'm yet to get zapped by US
power... :-)

cheers

Jules

AC was adopted in the US because its easy to transport, stepping up
and down voltages to send current cross country.

thomas edison prefered DC, thinking it was safer

Ivan wrote:
Just in case this guy was serious:

1) What makes you think DC is cheaper if nobody offers it for sale?
2) Don't blame the people you spoke to on the phone for not knowing
about DC--odds are you were the first person to make this request in
the last 90 years--if ever.
3) I used to work in a NY office building with DC; since that wouldn't
run air-conditioning, they gave us salt tablets. My college dorm was
DC, too, and we had to buy converters to run our stereo and
refrigerator--with the amount of electronics in today's dorms, we
would have been driven crazy.
Nothing is your house will run except incandescent lights.
Freezer, Refrigerator, TV, stereo, appliances, tools, nothing will work
on DC unless you change it all out with DC appliances.
Build your own rectifier bridge and make your own DC. Solar panels put
out DC, get some of those.




--
LSMFT

I'm trying to think but nothing happens.........

On 2010-04-07, wrote:
On Tue, 06 Apr 2010 17:25:22 -0500, wrote:

What comes from a car's ignition coil? I got knocked on my ass from
that a few times. Damn that hurts !!!!

In excess of 60,000 volts AC

That's DC, not AC. It feels like AC cuz it's being delivered
repeatedly, the faster the engine's RPMs --and thus the distributor--
the faster the repititions of coil dicharges (X4, X6. X8).

nb

On Apr 6, 5:25*pm, wrote:
On Tue, 06 Apr 2010 16:10:51 -0400, Peter wrote:
On 4/6/2010 3:37 PM, wrote:
On Tue, 6 Apr 2010 12:03:40 -0700 (PDT),
wrote:

As for safety, I have never experienced a 120volt DC shock. *Has
anyone? *Is it less painful or harmful than 120v AC? *I have no
idea.... *I know that a 12VDC car battery can not shock a person, or
at least it's not noticable.

The great danger from power company AC (more so in the Northern Hemisphere than
in the rest of the world) is the 60 Hz frequency - which is close enough to your
heart muscle's pacemaker to throw you into ventricular fibrillation (which is
lethal unless defibrillated with a DC shock). *Outside of the Northern
Hemisphere they tend to use 50 Hz, which is somewhat less dangerous because it
is less likely than 60 Hz to ruin your entire day!

Interesting info..... *I never knew that about the "pacemaker".
Why do they use 50 or 60 Hz in different places?

History.

*Who determined what they use, and why? *

The power companies, then the governments involved (to homogenize
service).

I imagine that what ever is connected to it will operate differently too,

Some yes, some no.

except for filament lightbulbs.

Correct, though there is some flicker from light bulbs, too.

*What effect does it have on a motor made for 60hz if its run on 50hz?

Depends on the motor. An induction motor will run at the line
frequency, in this case at 5/6ths the RPM. A universal motor won't
care.

*Or a transformer? *

A 50Hz transformer will run at 60Hz just fine. A 60Hz transformer has
to be derated to run at 50Hz or it'll get too hot.

And what about a SCR light dimmer?

Should work fine at either frequency.

Come to think about it, what determines whether the output from a
generator is 50 or 60 hz? *Is it the number of windings in the
generator coil, or the speed it spins, or what? *

Both the number of poles (not the number of turns) and the RPM.

What would happen if they used 30 hz, or 80? *

Nights would flicker, there would be more loss.

I understand how generators work, but *I
never understood how they achieve the HZ rate. *I can only assume that
the output from a portable gasoline generator in the USA is 60Hz, so
it matches that of the common outlets in this part of the world. *Most
of the time when you buy a generator, you only look at the amps or
watts rating, and whether they provide 120V or 240V (or both).

KVA rating is rather important too.

AC shocks produce a sensation of intense vibration without a lot of motion in
your muscles, which can make it very easy to continue to hold on to whatever you
have touched that is conducting the shock. *DC shocks produce a violent
contraction in the muscles, which if you are lucky will cause you to jerk away
from the conducting object. *They both can be quite painful, depending upon the
amount of current and the duration of the shocks.

What comes from a car's ignition coil? *I got knocked on my ass from
that a few times. *Damn that hurts !!!!


Don't believe that you cannot receive a really painful and/or injurious shock
from a car battery. *It depends upon your resistance (are you full of
perspiration at the time you receive the shock or is your skin entirely intact
and dry). *Car batteries can deliver a really nasty high amperage shock if the
resistance in the shock path is low and you can get really nasty burns from the
heat that can be generated.

Guess I have been lucky. *I never have felt a thing from touching a
live 12v wire in a car.

Anything less that 50V is considered "safe" to touch. Your skin has a
natural resistance that protects you. Penetrate the skin and all bets
are off. Lay your tongue on a 9v battery and see what it tastes
like. ;-)

The damage from a shock is related to the energy (watts) delivered which is the
product of the voltage and the current. *The lower the resistance, the higher
the current (given a constant voltage).

nonsense.

On Apr 7, 7:31*am, Jules Richardson
wrote:
On Tue, 06 Apr 2010 22:07:33 -0400, clare wrote:
As for safety - AC and DC are relatively * equal as far as shocks are
concerned - if *12 *volts DC does not give a shock, 12 volts *AC won't
either. *The only difference is *a *DC shock is a "single *hit" while AC
is a "buzzzz" WHich is more dangerous? Since *AC hurts more, I'd say DC
is the more dangerous - easier to ignore??????

Lots of old railroad engineers have told me that DC was far worse because
it can make muscles contract - and then you can't let go of whatever it
is that's causing the shock. Whether there's truth in that, I'm not
sure...

There is.

I don't know how many 240V AC shocks I've had over the years when I lived
in the UK, but certainly quite a few. I'm yet to get zapped by US
power... :-)

It hurts too, but our normal household service is half (120V) of what
you have. A 240V outlet, only used for large appliances, has two such
wires (the 240V is split with a center tap tied to ground) but you'd
have to work to get across both wires.

On Apr 7, 8:36*am, " wrote:
AC was adopted in the US because its easy to transport, stepping up
and down voltages to send current cross country.

thomas edison prefered DC, thinking it was safer

Thomas Edison preferred DC because he built his power system on DC and
AC was developed by a competitor (Tesla, working for Westinghouse).

On Apr 6, 6:25*pm, wrote:
On Tue, 06 Apr 2010 16:10:51 -0400, Peter wrote:
On 4/6/2010 3:37 PM, wrote:
On Tue, 6 Apr 2010 12:03:40 -0700 (PDT),
wrote:

Why do they use 50 or 60 Hz in different places? *Who determined what
they use, and why?. . . .
*What would happen if they used 30 hz, or 80? *

With an interconnected power grid, it's vital that all intersections
be PRECISELY synchronized.
By the way, one consequence of the different power frequencies in
Europe and the US was TV standards, which originally were synched to
the power lines: European TV had slightly more perceptible flicker,
due to a slower frame rate (50 fields per second to our 60), though
most Euro systems did have higher definition for reasons unrelated to
powerline frequency.

Ivan wrote:
Just in case this guy was serious:

1) What makes you think DC is cheaper if nobody offers it for sale?
2) Don't blame the people you spoke to on the phone for not knowing
about DC--odds are you were the first person to make this request in
the last 90 years--if ever.
3) I used to work in a NY office building with DC; since that wouldn't
run air-conditioning, they gave us salt tablets. My college dorm was
DC, too, and we had to buy converters to run our stereo and
refrigerator--with the amount of electronics in today's dorms, we
would have been driven crazy.
Hmmm,
I guess he wants to replace alternator with generator in his car too.

HOWEVER,
I read recently that research into high-voltage transmission was
suggesting that very high voltage DC transmission was more efficient that
AC -- proly due to lack of capacitance/inductive effects et al, or some
other wizardry -- and that with the advent of solid state inverters,
transforming DC to AC would be less problematic, rendering DC transmission
ultimately viable.



MB Hydro uses DC for transmission from generator sites to converter stations
over hundreds of miles.

http://www.hydro.mb.ca/corporate/fac...s_nelson.shtml

"Iowna Uass" wrote in message
...
HOWEVER,
I read recently that research into high-voltage transmission was
suggesting that very high voltage DC transmission was more efficient that
AC -- proly due to lack of capacitance/inductive effects et al, or some
other wizardry -- and that with the advent of solid state inverters,
transforming DC to AC would be less problematic, rendering DC
transmission ultimately viable.



MB Hydro uses DC for transmission from generator sites to converter
stations over hundreds of miles.

http://www.hydro.mb.ca/corporate/fac...s_nelson.shtml



Very inneresting. The article said the technology for HV DC transmission
came about in the '60s, altho it's not clear when it was actually
implemented. I suspect it was in the late '80s, or '90s.

The article seemed to imply that this hydroelectric plant was *dependent* on
the technology of DC... don't know why AC would not have sufficed.
--
EA

On Apr 6, 3:37*pm, wrote:
On Tue, 6 Apr 2010 12:03:40 -0700 (PDT), Ivan
wrote:

Just in case this guy was serious:

1) What makes you think DC is cheaper if nobody offers it for sale?
2) Don't blame the people you spoke to on the phone for not knowing
about DC--odds are you were the first person to make this request in
the last 90 years--if ever.
3) I used to work in a NY office building with DC; since that wouldn't
run air-conditioning, they gave us salt tablets. *My college dorm was
DC, too, and we had to buy converters to run our stereo and
refrigerator--with the amount of electronics in today's dorms, we
would have been driven crazy.

Even though it's not practical to distribute DC because of the wire
thickness needed as well as losses, *in some ways I can see where
there can be some confusion. *With DC, the power goes directly to the
device. *For example, in a flashlight, the DC batteries send the
electric power directly to the lightbulb (thus the word DIRECT).

With AC, the power goes thru the bulb and is returned to the source
minus what was lost from heating the filament in the bulb (mostly the
loss is from heat). *Knowing that, I always wondered just how much of
the electric is returned to the power company in an AC system. *Since
that returned power has gone thru our electric meter, does the power
company sell the same electric twice or more times? *Maybe there is
some truth in DC being cheaper to the consumer, (not taking into
consideration the much higher costs to distribute it). *I have always
wondered what happened to that returned power in an AC system.

Whether it's AC or DC the current flows from the source, through the
load and back to the source. It matters not a wit whether it's AC or
DC from a metering or usage standpoint. The only difference is that
with AC the direction of the current changes once during each cycle.

On Apr 7, 4:34�pm, "Iowna Uass" wrote:
HOWEVER,
� I read recently that research into high-voltage transmission was
suggesting that very high voltage DC transmission was more efficient that
AC -- proly due to lack of capacitance/inductive effects et al, or some
other wizardry -- and that with the advent of solid state inverters,
transforming DC to AC would be less problematic, rendering DC transmission
ultimately viable.

MB Hydro uses DC for transmission from generator sites to converter stations
over hundreds of miles.

http://www.hydro.mb.ca/corporate/fac...s_nelson.shtml

There are numerous high voltage DC links in the world including one
lnking the UK with continental Europe. The reason is difficulties in
synchronising the AC systems.
The plan was to take advantage of differing peak load times in France
and the UK.

On Apr 7, 3:51�pm, Ivan wrote:
On Apr 7, 8:36�am, " wrote:

AC was adopted in the US because its easy to transport, stepping up
and down voltages to send current cross country.

thomas edison prefered DC, thinking it was safer

Thomas Edison preferred DC because he built his power system on DC and
AC was developed by a competitor (Tesla, working for Westinghouse).

AC is in fact more dangerous. When you say 120 volts AC, that is only
the RMS voltage (a kind of average) The peak voltage is nearly
200volts.
The 120 volts AC will give exactly the same watts output as 120volts
DC if connected to the same resistor. But the 200 volts (peak) is
clearly more dangerous.
So Edison was right.

On Wed, 7 Apr 2010 12:31:47 +0000 (UTC), Jules Richardson
wrote:

On Tue, 06 Apr 2010 22:07:33 -0400, clare wrote:
As for safety - AC and DC are relatively equal as far as shocks are
concerned - if 12 volts DC does not give a shock, 12 volts AC won't
either. The only difference is a DC shock is a "single hit" while AC
is a "buzzzz" WHich is more dangerous? Since AC hurts more, I'd say DC
is the more dangerous - easier to ignore??????

Lots of old railroad engineers have told me that DC was far worse because
it can make muscles contract - and then you can't let go of whatever it
is that's causing the shock. Whether there's truth in that, I'm not
sure...

I don't know how many 240V AC shocks I've had over the years when I lived
in the UK, but certainly quite a few. I'm yet to get zapped by US
power... :-)

cheers

Jules
The DC muscle contraction is true - when the current gets high enough
to cramp your muscles on AC it reverses and you have a chance to let
go - On DC it is constant polarity and your muscle never relaxes.

On Apr 7, 6:38*pm, wrote:
On Wed, 7 Apr 2010 12:31:47 +0000 (UTC), Jules Richardson





wrote:
On Tue, 06 Apr 2010 22:07:33 -0400, clare wrote:
As for safety - AC and DC are relatively * equal as far as shocks are
concerned - if *12 *volts DC does not give a shock, 12 volts *AC won't
either. *The only difference is *a *DC shock is a "single *hit" while AC
is a "buzzzz" WHich is more dangerous? Since *AC hurts more, I'd say DC
is the more dangerous - easier to ignore??????

Lots of old railroad engineers have told me that DC was far worse because
it can make muscles contract - and then you can't let go of whatever it
is that's causing the shock. Whether there's truth in that, I'm not
sure...

I don't know how many 240V AC shocks I've had over the years when I lived
in the UK, but certainly quite a few. I'm yet to get zapped by US
power... :-)

cheers

Jules

*The DC muscle contraction is true - when the current gets high enough
to cramp your muscles on AC it reverses and you have a chance to let
go -


How the hell can you have time to let go when the whole AC cycle is
1/60 of a second, the amount of time the voltage is close to zero,
being but a small fraction of that?



On DC it is *constant polarity and your muscle never relaxes.- Hide
quoted text -

- Show quoted text -

On Wed, 7 Apr 2010 17:56:34 -0700 (PDT), wrote:

On Apr 7, 6:38Â*pm, wrote:
On Wed, 7 Apr 2010 12:31:47 +0000 (UTC), Jules Richardson





wrote:
On Tue, 06 Apr 2010 22:07:33 -0400, clare wrote:
As for safety - AC and DC are relatively Â* equal as far as shocks are
concerned - if Â*12 Â*volts DC does not give a shock, 12 volts Â*AC won't
either. Â*The only difference is Â*a Â*DC shock is a "single Â*hit" while AC
is a "buzzzz" WHich is more dangerous? Since Â*AC hurts more, I'd say DC
is the more dangerous - easier to ignore??????

Lots of old railroad engineers have told me that DC was far worse because
it can make muscles contract - and then you can't let go of whatever it
is that's causing the shock. Whether there's truth in that, I'm not
sure...

I don't know how many 240V AC shocks I've had over the years when I lived
in the UK, but certainly quite a few. I'm yet to get zapped by US
power... :-)

cheers

Jules

Â*The DC muscle contraction is true - when the current gets high enough
to cramp your muscles on AC it reverses and you have a chance to let
go -


How the hell can you have time to let go when the whole AC cycle is
1/60 of a second, the amount of time the voltage is close to zero,
being but a small fraction of that?


Muscle contraction is somewhat directional ? related to polarity and
with AC the contraction is not as strong and steady as with DC because
it is (a) interupted (b) reduced to RMS and possibly (c) reduced due
to palarity reversal

On DC it is Â*constant polarity and your muscle never relaxes.- Hide
quoted text -

- Show quoted text -

On Apr 7, 2:46*pm, harry wrote:
On Apr 7, 4:34 pm, "Iowna Uass" wrote:

HOWEVER,
I read recently that research into high-voltage transmission was
suggesting that very high voltage DC transmission was more efficient that
AC -- proly due to lack of capacitance/inductive effects et al, or some
other wizardry -- and that with the advent of solid state inverters,
transforming DC to AC would be less problematic, rendering DC transmission
ultimately viable.

MB Hydro uses DC for transmission from generator sites to converter stations
over hundreds of miles.

http://www.hydro.mb.ca/corporate/fac...s_nelson.shtml

There are numerous high voltage DC links in the world including one
lnking the UK with continental Europe. The reason is difficulties in
synchronising the AC systems.

That's not the only reason for DC links. DC transmission losses are
less than AC, as well. For long distances these losses are greater
than the expense of conversion.

The plan was to take advantage of differing peak load times in France
and the UK.

On 4/7/2010 10:44 AM, keith wrote:


The damage from a shock is related to the energy (watts) delivered which is the
product of the voltage and the current. The lower the resistance, the higher
the current (given a constant voltage).

nonsense.

Keith, please explain how and why Ohm's law is "nonsense"?

Or, were you saying that the damage from a shock is not related to the energy
delivered?

To expand on my original statement, electrical shock damage is directly related
to the extent and magnitude of tissue heating. I'm not talking about
neuro-muscular depolarazation - which can produce cardiac dysrhythmias or
orthopedic damage from violent muscular contraction. I'm talking about dead
tissue (skin, muscle, fat, tendons, nerves, internal organs, internally
coagulated blood, even bones, severe swelling from compartment syndromes etc.

I want to hear more about the nonsense.

On Apr 8, 10:49*am, Peter wrote:
On 4/7/2010 10:44 AM, keith wrote:



The damage from a shock is related to the energy (watts) delivered which is the
product of the voltage and the current. *The lower the resistance, the higher
the current (given a constant voltage).

nonsense.

Keith, please explain how and why Ohm's law is "nonsense"?

I said nothing about Ohm's law being nonsense.

Or, were you saying that the damage from a shock is not related to the energy
delivered?

Partially. It doesn't take much energy to kill and more isn't going
to make you any deader. Skin has a very non-linear resistance so
Ohm's law doesn't hold, at least as stated.

To expand on my original statement, electrical shock damage is directly related
to the extent and magnitude of tissue heating. *I'm not talking about
neuro-muscular depolarazation - which can produce cardiac dysrhythmias or
orthopedic damage from violent muscular contraction. *I'm talking about dead
tissue (skin, muscle, fat, tendons, nerves, internal organs, internally
coagulated blood, even bones, severe swelling from compartment syndromes etc.

So you don't consider death by fibrillation to be "damage"? How far
you have to move the goal posts to justify your nonsense isn't
important. You've stated a falshood that could get someone in
trouble.

I want to hear more about the nonsense.

Keep talking, then read what you've written.

On 4/8/2010 1:43 PM, keith wrote:
On Apr 8, 10:49 am, wrote:
On 4/7/2010 10:44 AM, keith wrote:



The damage from a shock is related to the energy (watts) delivered which is the
product of the voltage and the current. The lower the resistance, the higher
the current (given a constant voltage).

nonsense.

Keith, please explain how and why Ohm's law is "nonsense"?

I said nothing about Ohm's law being nonsense.

Or, were you saying that the damage from a shock is not related to the energy
delivered?

Partially. It doesn't take much energy to kill and more isn't going
to make you any deader. Skin has a very non-linear resistance so
Ohm's law doesn't hold, at least as stated.

To expand on my original statement, electrical shock damage is directly related
to the extent and magnitude of tissue heating. I'm not talking about
neuro-muscular depolarazation - which can produce cardiac dysrhythmias or
orthopedic damage from violent muscular contraction. I'm talking about dead
tissue (skin, muscle, fat, tendons, nerves, internal organs, internally
coagulated blood, even bones, severe swelling from compartment syndromes etc.

So you don't consider death by fibrillation to be "damage"? How far
you have to move the goal posts to justify your nonsense isn't
important. You've stated a falshood that could get someone in
trouble.

I want to hear more about the nonsense.

Keep talking, then read what you've written.
I have read what I wrote. And, what you wrote. Your "nonsense" comment could
have referred to either issue.

In any case, I believe you are still wrong to discount (by saying "nonsense")
the fact that damage is related to energy delivered even if, for the purposes of
this discussion, I accept your definition of damage to include death by
fibrillation (not defibrillation as you wrote). You seem to be confusing or at
least conflating the specific issue of pathway through the body with the
conceptual issue of sufficient energy to produce a specifically defined
"damage". Surely you have to acknowledge that if the shock delivers
insufficient energy, it won't cause any damage, much less death.

Again, what exactly did I say that you consider to be "nonsense" Inquiring
minds want to know.

On Thu, 08 Apr 2010 13:53:57 -0400, Peter wrote:

On 4/8/2010 1:43 PM, keith wrote:
On Apr 8, 10:49 am, wrote:
On 4/7/2010 10:44 AM, keith wrote:



The damage from a shock is related to the energy (watts) delivered which is the
product of the voltage and the current. The lower the resistance, the higher
the current (given a constant voltage).

nonsense.

Keith, please explain how and why Ohm's law is "nonsense"?

I said nothing about Ohm's law being nonsense.

Or, were you saying that the damage from a shock is not related to the energy
delivered?

Partially. It doesn't take much energy to kill and more isn't going
to make you any deader. Skin has a very non-linear resistance so
Ohm's law doesn't hold, at least as stated.

To expand on my original statement, electrical shock damage is directly related
to the extent and magnitude of tissue heating. I'm not talking about
neuro-muscular depolarazation - which can produce cardiac dysrhythmias or
orthopedic damage from violent muscular contraction. I'm talking about dead
tissue (skin, muscle, fat, tendons, nerves, internal organs, internally
coagulated blood, even bones, severe swelling from compartment syndromes etc.

So you don't consider death by fibrillation to be "damage"? How far
you have to move the goal posts to justify your nonsense isn't
important. You've stated a falshood that could get someone in
trouble.

I want to hear more about the nonsense.

Keep talking, then read what you've written.
I have read what I wrote. And, what you wrote. Your "nonsense" comment could
have referred to either issue.

In any case, I believe you are still wrong to discount (by saying "nonsense")
the fact that damage is related to energy delivered even if, for the purposes of
this discussion, I accept your definition of damage to include death by
fibrillation (not defibrillation as you wrote). You seem to be confusing or at
least conflating the specific issue of pathway through the body with the
conceptual issue of sufficient energy to produce a specifically defined
"damage". Surely you have to acknowledge that if the shock delivers
insufficient energy, it won't cause any damage, much less death.

That is *NOT* the same thing as saying that the amount of damage is
proportional to the energy. It is most certainly *not*.

Again, what exactly did I say that you consider to be "nonsense" Inquiring
minds want to know.

Shock damage ~= energy

On Thu, 08 Apr 2010 17:52:55 -0500, "
wrote:

On Thu, 08 Apr 2010 13:53:57 -0400, Peter wrote:

On 4/8/2010 1:43 PM, keith wrote:
On Apr 8, 10:49 am, wrote:
On 4/7/2010 10:44 AM, keith wrote:



The damage from a shock is related to the energy (watts) delivered which is the
product of the voltage and the current. The lower the resistance, the higher
the current (given a constant voltage).

nonsense.

Keith, please explain how and why Ohm's law is "nonsense"?

I said nothing about Ohm's law being nonsense.

Or, were you saying that the damage from a shock is not related to the energy
delivered?

Partially. It doesn't take much energy to kill and more isn't going
to make you any deader. Skin has a very non-linear resistance so
Ohm's law doesn't hold, at least as stated.

To expand on my original statement, electrical shock damage is directly related
to the extent and magnitude of tissue heating. I'm not talking about
neuro-muscular depolarazation - which can produce cardiac dysrhythmias or
orthopedic damage from violent muscular contraction. I'm talking about dead
tissue (skin, muscle, fat, tendons, nerves, internal organs, internally
coagulated blood, even bones, severe swelling from compartment syndromes etc.

So you don't consider death by fibrillation to be "damage"? How far
you have to move the goal posts to justify your nonsense isn't
important. You've stated a falshood that could get someone in
trouble.

I want to hear more about the nonsense.

Keep talking, then read what you've written.
I have read what I wrote. And, what you wrote. Your "nonsense" comment could
have referred to either issue.

In any case, I believe you are still wrong to discount (by saying "nonsense")
the fact that damage is related to energy delivered even if, for the purposes of
this discussion, I accept your definition of damage to include death by
fibrillation (not defibrillation as you wrote). You seem to be confusing or at
least conflating the specific issue of pathway through the body with the
conceptual issue of sufficient energy to produce a specifically defined
"damage". Surely you have to acknowledge that if the shock delivers
insufficient energy, it won't cause any damage, much less death.

That is *NOT* the same thing as saying that the amount of damage is
proportional to the energy. It is most certainly *not*.

Again, what exactly did I say that you consider to be "nonsense" Inquiring
minds want to know.

Shock damage ~= energy

Oh, and Ohms law has any meaning, here.

On 4/8/2010 6:54 PM, zzzzzzzzzz wrote:
On Thu, 08 Apr 2010 17:52:55 -0500, "
wrote:

On Thu, 08 Apr 2010 13:53:57 -0400, wrote:

On 4/8/2010 1:43 PM, keith wrote:
On Apr 8, 10:49 am, wrote:
On 4/7/2010 10:44 AM, keith wrote:



The damage from a shock is related to the energy (watts) delivered which is the
product of the voltage and the current. The lower the resistance, the higher
the current (given a constant voltage).

nonsense.

Keith, please explain how and why Ohm's law is "nonsense"?

I said nothing about Ohm's law being nonsense.

Or, were you saying that the damage from a shock is not related to the energy
delivered?

Partially. It doesn't take much energy to kill and more isn't going
to make you any deader. Skin has a very non-linear resistance so
Ohm's law doesn't hold, at least as stated.

To expand on my original statement, electrical shock damage is directly related
to the extent and magnitude of tissue heating. I'm not talking about
neuro-muscular depolarazation - which can produce cardiac dysrhythmias or
orthopedic damage from violent muscular contraction. I'm talking about dead
tissue (skin, muscle, fat, tendons, nerves, internal organs, internally
coagulated blood, even bones, severe swelling from compartment syndromes etc.

So you don't consider death by fibrillation to be "damage"? How far
you have to move the goal posts to justify your nonsense isn't
important. You've stated a falshood that could get someone in
trouble.

I want to hear more about the nonsense.

Keep talking, then read what you've written.
I have read what I wrote. And, what you wrote. Your "nonsense" comment could
have referred to either issue.

In any case, I believe you are still wrong to discount (by saying "nonsense")
the fact that damage is related to energy delivered even if, for the purposes of
this discussion, I accept your definition of damage to include death by
fibrillation (not defibrillation as you wrote). You seem to be confusing or at
least conflating the specific issue of pathway through the body with the
conceptual issue of sufficient energy to produce a specifically defined
"damage". Surely you have to acknowledge that if the shock delivers
insufficient energy, it won't cause any damage, much less death.

That is *NOT* the same thing as saying that the amount of damage is
proportional to the energy. It is most certainly *not*.

Again, what exactly did I say that you consider to be "nonsense" Inquiring
minds want to know.

Shock damage ~= energy

Oh, and Ohms law has any meaning, here.
It is impossible to have a meaning discussion with someone who rebuts fully
explained positions with negative declarative one-liners that are totally devoid
of explanation. I'm moving on.

On Fri, 09 Apr 2010 09:47:55 -0400, Peter wrote:

On 4/8/2010 6:54 PM, zzzzzzzzzz wrote:
On Thu, 08 Apr 2010 17:52:55 -0500, "
wrote:

On Thu, 08 Apr 2010 13:53:57 -0400, wrote:

On 4/8/2010 1:43 PM, keith wrote:
On Apr 8, 10:49 am, wrote:
On 4/7/2010 10:44 AM, keith wrote:



The damage from a shock is related to the energy (watts) delivered which is the
product of the voltage and the current. The lower the resistance, the higher
the current (given a constant voltage).

nonsense.

Keith, please explain how and why Ohm's law is "nonsense"?

I said nothing about Ohm's law being nonsense.

Or, were you saying that the damage from a shock is not related to the energy
delivered?

Partially. It doesn't take much energy to kill and more isn't going
to make you any deader. Skin has a very non-linear resistance so
Ohm's law doesn't hold, at least as stated.

To expand on my original statement, electrical shock damage is directly related
to the extent and magnitude of tissue heating. I'm not talking about
neuro-muscular depolarazation - which can produce cardiac dysrhythmias or
orthopedic damage from violent muscular contraction. I'm talking about dead
tissue (skin, muscle, fat, tendons, nerves, internal organs, internally
coagulated blood, even bones, severe swelling from compartment syndromes etc.

So you don't consider death by fibrillation to be "damage"? How far
you have to move the goal posts to justify your nonsense isn't
important. You've stated a falshood that could get someone in
trouble.

I want to hear more about the nonsense.

Keep talking, then read what you've written.
I have read what I wrote. And, what you wrote. Your "nonsense" comment could
have referred to either issue.

In any case, I believe you are still wrong to discount (by saying "nonsense")
the fact that damage is related to energy delivered even if, for the purposes of
this discussion, I accept your definition of damage to include death by
fibrillation (not defibrillation as you wrote). You seem to be confusing or at
least conflating the specific issue of pathway through the body with the
conceptual issue of sufficient energy to produce a specifically defined
"damage". Surely you have to acknowledge that if the shock delivers
insufficient energy, it won't cause any damage, much less death.

That is *NOT* the same thing as saying that the amount of damage is
proportional to the energy. It is most certainly *not*.

Again, what exactly did I say that you consider to be "nonsense" Inquiring
minds want to know.

Shock damage ~= energy

Oh, and Ohms law has any meaning, here.
It is impossible to have a meaning discussion with someone who rebuts fully
explained positions with negative declarative one-liners that are totally devoid
of explanation. I'm moving on.

When proven to be the idiot he is, he simply does a hit-and-run. Figures.

On Tue, 06 Apr 2010 14:37:11 -0500, wrote:



[snip]

I have always
wondered what happened to that returned power in an AC system.

The meters they use have a special "return coil" on the neutral wire.
This has the effect of reducing the meter reading by the amount of
returned power. However, in one independent test done in 2008 showed
that 83.7% of power-company-owned meters have the return coil
connected backward. You need to contact your power company to make
sure your return coil is connected properly. They are required to
provide this service free of charge at last once every 5 years or
sooner if the meter has been replaced.

[snip]

On Wed, 7 Apr 2010 12:51:57 -0700 (PDT), harry
wrote:

On Apr 7, 3:51?pm, Ivan wrote:
On Apr 7, 8:36?am, " wrote:

AC was adopted in the US because its easy to transport, stepping up
and down voltages to send current cross country.

thomas edison prefered DC, thinking it was safer

Thomas Edison preferred DC because he built his power system on DC and
AC was developed by a competitor (Tesla, working for Westinghouse).

AC is in fact more dangerous. When you say 120 volts AC, that is only
the RMS voltage (a kind of average) The peak voltage is nearly
200volts.

170V

The 120 volts AC will give exactly the same watts output as 120volts
DC if connected to the same resistor. But the 200 volts (peak) is
clearly more dangerous.
So Edison was right.

[snip]

Whether it's AC or DC the current flows from the source, through the
load and back to the source. It matters not a wit whether it's AC or
DC from a metering or usage standpoint. The only difference is that
with AC the direction of the current changes once during each cycle.





"once" here means twice.

On Wed, 16 Jun 2010 20:06:49 -0500, Sam E
wrote:

On Wed, 7 Apr 2010 12:51:57 -0700 (PDT), harry
wrote:

On Apr 7, 3:51?pm, Ivan wrote:
On Apr 7, 8:36?am, " wrote:

AC was adopted in the US because its easy to transport, stepping up
and down voltages to send current cross country.

thomas edison prefered DC, thinking it was safer

Thomas Edison preferred DC because he built his power system on DC and
AC was developed by a competitor (Tesla, working for Westinghouse).

AC is in fact more dangerous. When you say 120 volts AC, that is only
the RMS voltage (a kind of average) The peak voltage is nearly
200volts.

170V

The 120 volts AC will give exactly the same watts output as 120volts
DC if connected to the same resistor. But the 200 volts (peak) is
clearly more dangerous.
So Edison was right.


Either one will make for a bad day.

In ,
Sam E typed:
On Wed, 7 Apr 2010 12:51:57 -0700 (PDT), harry
wrote:

On Apr 7, 3:51?pm, Ivan wrote:
On Apr 7, 8:36?am, "
wrote:

AC was adopted in the US because its easy to transport,
stepping up and down voltages to send current cross
country.

thomas edison prefered DC, thinking it was safer

Thomas Edison preferred DC because he built his power
system on DC and AC was developed by a competitor (Tesla,
working for Westinghouse).

AC is in fact more dangerous. When you say 120 volts AC,
that is only the RMS voltage (a kind of average) The peak
voltage is nearly 200volts.

170V

The 120 volts AC will give exactly the same watts output
as 120volts DC if connected to the same resistor. But the
200 volts (peak) is clearly more dangerous.
So Edison was right.

But DC cannot be changed via a transformer so the high voltages necessary to
provide the end-use currents would/could not safely exist. A little more
research would also show you that ac voltages are safer than the DC. DC
clamps and holds the muscles, causing quicker death than ac.
Claims such as the DC hoax postulated here are usually the work of trolls
misinformationists and guessers.