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.
Yes; same in 1953 when I was working for the summer in Gloucester (UK)
it was 220 volts DC.
Not sure why in that town it was DC.
But DC was sometimes used where and when an industrial plant/factory
also supplied the town or part of the town around. In this part of
Canada the whole are is, now, North American standard 115/230 volts 60
hertz. But until sometime in the 1960s (some ten to fifteen years
after this province joined Canada in 1949) there were areas provided
with electrcity from local paper mills, which were originally British
based companies! So customers were supplied 115/230 at fifty (50)
Another reason for DC was sometimes because it was/is used by street
railways etc. Have no experience with that.
Some lumber factories I I am told used 25 hertz for motors; and
somewhere I have the power transformer from a scrapped 25 hertz B&W
TV, shipped in when TV was first introduced here in 1954/55 and there
was demand for new TVs of any kind!
The original poster is 'just having us on to their troll'.
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.
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
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
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
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
I have read medical opinion to the opposite, that AC is the more
dangerous, altho with no real physiologic reasoning. I suspect they are
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
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
Hey, Tony, mebbe you and Heffron can chip in on an electricity book -- mebbe
one without calculus....
>> >> As for safety, I have never experienced a 120volt DC shock. Has
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.
On 4/6/2010 3:37 PM, J email@example.com wrote:
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).
Interesting info..... I never knew that about the "pacemaker".
Why do they use 50 or 60 Hz in different places? Who determined what
they use, and why? I imagine that what ever is connected to it will
operate differently too, except for filament lightbulbs. What effect
does it have on a motor made for 60hz if its run on 50hz? Or a
transformer? And what about a SCR light dimmer?
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? What would happen if
they used 30 hz, or 80? 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).
What comes from a car's ignition coil? I got knocked on my ass from
that a few times. Damn that hurts !!!!
Guess I have been lucky. I never have felt a thing from touching a
live 12v wire in a car.
On Tue, 06 Apr 2010 17:25:22 -0500, J firstname.lastname@example.org wrote:
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
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
On Apr 6, 5:25 pm, J email@example.com wrote:
The power companies, then the governments involved (to homogenize
Some yes, some no.
Correct, though there is some flicker from light bulbs, too.
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
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.
Should work fine at either frequency.
Both the number of poles (not the number of turns) and the RPM.
Nights would flicker, there would be more loss.
KVA rating is rather important too.
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
Or, were you saying that the damage from a shock is not related to the energy
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.
HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here.
All logos and trade names are the property of their respective owners.