Why doesn't everything use high voltage power?

[PaperclipGod]

The higher the voltage, the more efficient the power transmission, right? So why doesn't everything use high voltage power?

Yes, I know I'm retarded for asking, but someone please take the time to answer in between guffaws! :awe:

 

[MJinZ]

More dangerous.

 

[meltdown75]

my answer isn't worth an "infraction" :awe:

 

[tatteredpotato]

Because you will die.

They do the backhaul over HV because not many people have to interact with it, and those who do are highly trained. The transmission to your house is a lower voltage, but still very dangerous to the untrained person. The transformers on the pole in front of your house step down voltages to "safe" levels.

 

[Perknose]

It's shocking that they don't, but would be even more shocking if they did.

 

[olds]

They do in Europe.

 

[Vette73]

We, US, are already setup for 120v and that system is already installed and used.

Many other countries use 240v, that is why you have to use convertors when you travel outside the US and the power supply in your computer has a 120/240 switch.

 

[rivan]

Because then I'd actually have to turn off my breakers to work on light switches.

</shiftyeyes>

 

[PaperclipGod]

What makes high voltage so much more dangerous? Aren't 120V devices just as capable of killing you? Isn't it like saying getting shot in the head with a bullet is "safer" than getting shot with a cruise missile?

 

[spidey07]

Data centers normally use 220 or DC. Less heat. What makes it more dangerous is longer arcing possibility.

That and our entire system is based on 120/60Hz.

 

[olds]

What makes high voltage so much more dangerous? Aren't 120V devices just as capable of killing you? Isn't it like saying getting shot in the head with a bullet is "safer" than getting shot with a cruise missile?

I've been shocked by 110v at least a dozen times. I never died any of those times.
I've been shocked by 220 once and I didn't die then, either.

 

[Demon-Xanth]

Higher voltage means you need more space for insulation. A 12V battery you can touch both terminals and not get hurt because it doesn't have enough potential to break down the dielectric barriers (unless you make a particularly good contact). 48V will give you a bit of a buzz. 120V will shock the crap out of you.

As far as why the US uses 110/120 instead of 220/240? Mainly infrastructure. 220/240 is available in most houses but is usually limited to high power devices like ovens and electric dryers. There is also 440 three phase that you will generally NOT see in residential houses that is usually used for very large machinery.

 

[Gibson486]

No, it's not more efficient. There are lots of upside to going 220/230/240 as opposed to 120, but efficiency is not one of them.

That said, we do transmit everything at high voltage. It, however, gets stepped down when it goes to service.

And, you are correct. 120V is still an arc flash hazard...however, the arc will not be as big as, say 460. AT 120, you are more worried about touching live wires, not the arcing itself.

 

[PieIsAwesome]

What makes high voltage so much more dangerous? Aren't 120V devices just as capable of killing you? Isn't it like saying getting shot in the head with a bullet is "safer" than getting shot with a cruise missile?

Not too sure, but:

Greater potential differences produce stronger electric fields which are more able to ionize the air (or other non-conductors) and "arc."

 

[PottedMeat]

high voltage what?

DC? AC? Voltage range?

50/60Hz AC is nice because all you need to step up or down is a transformer. DC->AC or DC->DC needs additional electronics.

Long distance is all tens to hundreds of kV everywhere anyway, except for some fairly short run HVDC lines. I think the 120/240 difference in homes was due to Edison.

 

[PaperclipGod]

I've been shocked by 110v at least a dozen times. I never died any of those times.
I've been shocked by 220 once and I didn't die then, either.

But would you be dead if you were shocked with 1200 volts?

I thought amperage was what you had to be careful of... i.e., 1200V and just 1mA wouldn't kill you, right?

Also, aren't fuseboxes and GFCI outlets a pretty foolproof way to increase the safety of electricity, regardless of its power?

I know the US already uses 120/220v 50/60hz, which precludes any actual infrastructure changes, but I'm just asking from a theoretical POV.

 

[rudder]

What makes high voltage so much more dangerous? Aren't 120V devices just as capable of killing you? Isn't it like saying getting shot in the head with a bullet is "safer" than getting shot with a cruise missile?

Dont know... since it is not the voltage that kills you but the amps! Running stuff at high voltage uses less amperage. All our servers here are on high voltage circuits. No one has died yet.

 

[PieIsAwesome]

high voltage what?

DC? AC? Voltage range?

50/60Hz AC is nice because all you need to step up or down is a transformer. DC->AC or DC->DC needs additional electronics.

Long distance is all tens to hundreds of kV everywhere anyway, except for some fairly short run HVDC lines. I think the 120/240 difference in homes was due to Edison.

I thought Edison was in favor of using DC over AC. Westinghouse was the one in favor of AC.

 

[Gibson486]

Not too sure, but:

Greater potential differences produce stronger electric fields which are more able to ionize the air (or other non-conductors) and "arc."

You got it. The higher the voltage, the more potential there is.

Remember, it's not voltage that kills you, but amperage. Going through fixed resistance, 460 V will dissipate more amperage than 120 V when looking for a path to ground.

 

[olds]

But would you be dead if you were shocked with 1200 volts?

I thought amperage was what you had to be careful of... i.e., 1200V and just 1mA wouldn't kill you, right?

Also, aren't fuseboxes and GFCI outlets a pretty foolproof way to increase the safety of electricity, regardless of its power?

I know the US already uses 120/220v 50/60hz, which precludes any actual infrastructure changes, but I'm just asking from a theoretical POV.

Now that you mention that, I have been shocked by a car coil which puts out in the neighborhood of 25, 000 volts.
I believe it's the amps that kill you.

 

[PaperclipGod]

No, it's not more efficient. There are lots of upside to going 220/230/240 as opposed to 120, but efficiency is not one of them.

That said, we do transmit everything at high voltage. It, however, gets stepped down when it goes to service.

And, you are correct. 120V is still an arc flash hazard...however, the arc will not be as big as, say 460. AT 120, you are more worried about touching live wires, not the arcing itself.

Is arcing still possible if the line is grounded, i.e., everything is installed properly? Again, I know it's probably a dumb question, but wouldn't a thick copper grounding wire almost always have a lower resistance than your body?

And what are the upsides of ~220V over 120V if not efficiency? I thought the main benefit of high voltage was to minimize the transmission loss. Or is it just that when talking about voltages so low already, the main benefit of 220V is packing more power into a transmission line?

 

[Gibson486]

But would you be dead if you were shocked with 1200 volts?

I thought amperage was what you had to be careful of... i.e., 1200V and just 1mA wouldn't kill you, right?

Also, aren't fuseboxes and GFCI outlets a pretty foolproof way to increase the safety of electricity, regardless of its power?

I know the US already uses 120/220v 50/60hz, which precludes any actual infrastructure changes, but I'm just asking from a theoretical POV.

yes, but working in the industry, I can tell you that a 10A breaker will not always trip at 10 Amps.

Yes, it is amperage that kills you, but that does not mean voltage does not matter. It's all about power to the load (voltage times current)

 

[overst33r]

I believe it's the amps that kill you.

That would explain the 100,000+v tasers.

 

[Lonyo]

No, it's not more efficient. There are lots of upside to going 220/230/240 as opposed to 120, but efficiency is not one of them.

That said, we do transmit everything at high voltage. It, however, gets stepped down when it goes to service.

And, you are correct. 120V is still an arc flash hazard...however, the arc will not be as big as, say 460. AT 120, you are more worried about touching live wires, not the arcing itself.

If it's not more efficient, then why is it more efficient? e.g. AT PSU tests show 230v tests getting higher efficiencies than the 120v tests.

 

[Modular]

V/R=I (Voltage/Resistance=Current)

Let's assume that the resistance in Old's body stays the same and he is shocked across the same parts of his body (ie. from left hand to left toe).

If the voltage was 120 and his resistance was 10 ohms (human bodies have MUCH higher resistance than that, but this is easy math for the concept of what's going on here), then the amperage coursing through his body would have a value of 12.

If the voltage was 220 and his resistance was 10 ohms, amperage would be 22.

You can see right away why it's much more dangerous to have higher voltage. Voltage is potential for electricity, while amperage is the actual "work" that the electrons are doing. Amperage is what kills you, voltage just gets the amperage there!