Actually, that's a misnomer. It takes 0.1 amps to stop your heart...

I think the point that I was trying to make was that for any given contact impedance (wet or dry, area of contact etc.) the higher voltage - within the domestic or industrial range - will drive a higher current: and as you say, it's the current which kills.

At very much higher voltages, one is usually saved by the inability of the source to provide any appreciable current - which is why schoolroom fun and games with Van de Graaff generators are permitted.

110v is misleading, it might say that on the tin but it is center tapped, ie +55v to -55v, so only a risk of a 55v shock.

Not so.....
At least here in the US....
Normal residential service is 110/220 or 120/240...
Each leg is 120v to ground or neutral or 240v between the two for appliances.
Nowhere can you get 55 or 60 volts.

Sorry was refuring to 110v used on UK construction sites, 110v between live - return but only 55v to earth.

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Kevin

At very much higher voltages, one is usually saved by the inability of the source to provide any appreciable current - which is why schoolroom fun and games with Van de Graaff generators are permitted.

Nope, they are permitted 'cause some of them kids just need to be juiced! :)

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"Two things are infinite: The universe and human stupidity; and I'm not sure about the universe." - Albert Einstein

As someone else above noted, there is less loss in the higher voltage. I know with water
the friction loss is exponential, I would expect similar results with power...after all, wiring and plumbing are very similar! :)

Yes, line losses are proportional to the square of the current (IIR)

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Donald
Infernal Optimist / Submariner, retired

On 240VAC, still with 3 conductors, you have hot hot ground. The two hots are on opposite phases, so there is no need for a neutral because the opposite-phases end up canceling each other out and makes a flat line, essentially. Now, half the amperage is drawn on each hot leg, but then there are two legs, so the power consumption is nearly identical. But what 240VAC will allow you to do is run a smaller gauge wire since only half the load is going to be on each conductor.

Not supposed to be three...should be four conductors...hot, hot, neutral
and ground. Each hot pulls off of a different post in the breaker panel
and as you also noted, neutral and ground are often (but shouldn't be)
connected together at the panel. I hate electricians that don't do this
right!

I would expect better efficiency from the higher voltage though. As someone
else above noted, there is less loss in the higher voltage. I know with water
the friction loss is exponential, I would expect similar results with
power...after all, wiring and plumbing are very similar! :)

Uhh...
If I am not mistaken, code here requires the neutral and earth ground to be bonded together at the main panel, but not at a sub-feed panel.

Out of curiosity. Might that get done as far back as in the meter? In every panel I have opened, in OK & NJ, the neutral & ground bus bars haven't been connected.

Also I normally see a small voltage potential between neutral & earth ground at the outlets. Normally <1v but I have seen as high as 3v between the two.

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Also I normally see a small voltage potential between neutral & earth ground at the outlets. Normally <1v but I have seen as high as 3v between the two.

This is due to the resistance between the ground and return. Any current caught in a ground loop, passes over that resistance, and causes a voltage. V=IR or Voltage = Current times Resistance. Where Voltage is in Volts (AC or DC), current in in Amps, and resistance is in Ohms.

Power (Watts) = Current (Amps) times voltage (Volts)

These equations can not be violated for any reason. If a circuit draws 100 watts, and the voltage drops, then it will draw more current to make up for it. This continues until the supply circuit can no longer handle it, and then total wattage decreases.

Steve

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Warning, addicted to SETI crunching!
Crunching as a member of GPU Users Group.
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Most good power supplies are actually more efficient at the higher voltage. A lot of the 80+ Golds just barely make gold on 110V but surpass it on 220V.

Most good power supplies are actually more efficient at the higher voltage. A lot of the 80+ Golds just barely make gold on 110V but surpass it on 220V.

+1.

There are always loss due to heat and if one recall scool, Q=I*I*R*t.
Power P=IU, so, if one transfer same power on higher voltage one will have lower current and lower Joule's heat generation. That's why long-range electricity transfers are always on very high voltages.

Also I normally see a small voltage potential between neutral & earth ground at the outlets. Normally <1v but I have seen as high as 3v between the two.

This is due to the resistance between the ground and return. Any current caught in a ground loop, passes over that resistance, and causes a voltage. V=IR or Voltage = Current times Resistance. Where Voltage is in Volts (AC or DC), current in in Amps, and resistance is in Ohms.

Power (Watts) = Current (Amps) times voltage (Volts)

Actually due to resistance in the neutral circuit. It is the one carrying the current. The ground circuit just carries the power to move the meter.

I might begin to worry at 3V if the conductor size was correct for the current being carried. Check your electric code.

I've seen some wild things here because the utility here uses a single cable, the two insulated hots wrapped around a bare neutral. The bare neutral is AL wrapped over a steel core. Squirrels like to sharpen their teeth on the AL and frequently break the connection. Then the steel has to carry the current and it isn't up to the task. Blinking lights all over the neighborhood.

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Also I normally see a small voltage potential between neutral & earth ground at the outlets. Normally <1v but I have seen as high as 3v between the two.

This is due to the resistance between the ground and return. Any current caught in a ground loop, passes over that resistance, and causes a voltage. V=IR or Voltage = Current times Resistance. Where Voltage is in Volts (AC or DC), current in in Amps, and resistance is in Ohms.

Power (Watts) = Current (Amps) times voltage (Volts)

Actually due to resistance in the neutral circuit. It is the one carrying the current. The ground circuit just carries the power to move the meter.

I might begin to worry at 3V if the conductor size was correct for the current being carried. Check your electric code.

I've seen some wild things here because the utility here uses a single cable, the two insulated hots wrapped around a bare neutral. The bare neutral is AL wrapped over a steel core. Squirrels like to sharpen their teeth on the AL and frequently break the connection. Then the steel has to carry the current and it isn't up to the task. Blinking lights all over the neighborhood.

The supply line going into my dads place was like that before he upgraded to 150A service. Which also resulted in it being a buried line.
I haven't seen anything over 1V in a while. Since I just got home from work I did some checking in my new place and I got between 80-90mV depending on the outlets location. It has been a few years since I finished my degree for electrical engineering, but I don't recall us doing to much with the NEC. Doing some checking NJ doesn't seem to have adopted the 2011 version yet.

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Not supposed to be three...should be four conductors...hot, hot, neutral
and ground.

Technically, yes, that is how it is supposed to be, but there are certain applications where it is required by the device. It is not always needed though. I know ranges (cooktop and oven in one unit) have hot-hot-neutral-ground, but clothes dryers have hot-hot-ground (newer, more modern ones have gone to 4-wire). Depends on the device for what kind of setup it is going to have. Hooking a computer power supply up for example, only has three conductors, so you can't have a neutral in there on 240VAC.

Uhh...
If I am not mistaken, code here requires the neutral and earth ground to be bonded together at the main panel, but not at a sub-feed panel.

Out of curiosity. Might that get done as far back as in the meter? In every panel I have opened, in OK & NJ, the neutral & ground bus bars haven't been connected.

It depends on the local code inspector and regulations for where you are. Around where I live, ground and neutral are bonded in the panel, but other municipalities require that they are separate even through the meter box. The power company ties the two together on the pole, so it still does the same thing anyway.

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