240/120v? why

[dreamsville]

Just wondering. I see some previous posts about books on the history of the electrical industries evolution. Why or how did we come to use 240/120v as the standard for single phase voltages in this country?

Different from a lot of other countries. Was there much experimentation with this or did Edison or somebody just come up with it and it stuck?

Just sitting around contemplating this Saturday morning

 

[Besoeker]

Just wondering. I see some previous posts about books on the history of the electrical industries evolution. Why or how did we come to use 240/120v as the standard for single phase voltages in this country?

Different from a lot of other countries. Was there much experimentation with this or did Edison or somebody just come up with it and it stuck?

Just sitting around contemplating this Saturday morning

I'm from UK and the general perception here is that your various different LV distribution voltages are more complex than need be.
Here we have just 400V 3-phase and 230V single phase (which is the line to neutral derived from the 400V 3-phase).
Almost all residences have just one voltage entering the premises - 230Vac, all domestic appliances are 230V including lighting, heating, washing machines etc.
No centre-tapped, no high leg, etc.

 

[mivey]

Why or how did we come to use 240/120v as the standard for single phase voltages in this country?

Since we do not use the metric system, and do not have the reasoning abilities of those from the UK and there-abouts, we basically just stumbled onto 120/240 by sheer dumb luck. :grin:

 

[mcclary's electrical]

Since we do not use the metric system, and do not have the reasoning abilities of those from the UK and there-abouts, we basically just stumbled onto 120/240 by sheer dumb luck. :grin:

:grin::grin:

 

[Besoeker]

Since we do not use the metric system, and do not have the reasoning abilities of those from the UK and there-abouts, we basically just stumbled onto 120/240 by sheer dumb luck. :grin:

And all manner of other voltages.....
Too late now to use a simpler and more logical system.
It would be too expensive to change now so you're stuck with what you have.....

 

[iwire]

I'm from UK and the general perception here is that your various different LV distribution voltages are more complex than need be.

And the perception here may be that those across the ocean can't handle more than one voltage. :grin:


Having grown up with it I do not find it complicated I find it good to have choices.

If I have a to move a lot of power I can use 480, if I need less power I can bring it to the end user at just 120 volt to ground instead of 230 to ground which IMO is no doubt safer.

 

[George Stolz]

Just wondering. I see some previous posts about books on the history of the electrical industries evolution.

I read Tom McNichol's book on the origins of distribution in the US, and found it to be an interesting read. IIRC, it doesn't directly answer your question, but I'd still recommend it.

 

[jumper]

If I have a to move a lot of power I can use 480, if I need less power I can bring it to the end user at just 120 volt to ground instead of 230 to ground which IMO is no doubt safer.

I am not so sure that I agree that 120v to ground vs 230v to ground would be safer overall.

Many DIYers and electricians do a lot of hack and hot work at 120v, yet respect 240v.

Since most shocks and such occur at 120v, would not 230v eliminate this particular problem.

Just a thought. IDK.

 

[iwire]

I am not so sure that I agree that 120v to ground vs 230v to ground would be safer overall.

Many DIYers and electricians do a lot of hack and hot work at 120v, yet respect 240v.

You figure if all homes were supplied with only 230 volt that the DIYs would stop?

I don't think that at all.

Since most shocks and such occur at 120v, would not 230v eliminate this particular problem.

I think that by far more people in the US are killed by 120 volt circuits is because by a far and large margin it is what more people are exposed to.

If the lowest voltage we used was 230 you would see the figures for 230 volt shocks skyrocket.

 

[jumper]

You figure if all homes were supplied with only 230 volt that the DIYs would stop?

I don't think that at all.




I think that by far more people in the US are killed by 120 volt circuits is because by a far and large margin it is what more people are exposed to.

If the lowest voltage we used was 230 you would see the figures for 230 volt shocks skyrocket.

Valid points.

As I said, It was just a thought to posit for discussion.

 

[LEO2854]

And all manner of other voltages.....
Too late now to use a simpler and more logical system.
It would be too expensive to change now so you're stuck with what you have.....

I am not so sure that I agree that 120v to ground vs 230v to ground would be safer overall.

Many DIYers and electricians do a lot of hack and hot work at 120v, yet respect 240v.

Since most shocks and such occur at 120v, would not 230v eliminate this particular problem.

Just a thought. IDK.

You figure if all homes were supplied with only 230 volt that the DIYs would stop?

I don't think that at all.




I think that by far more people in the US are killed by 120 volt circuits is because by a far and large margin it is what more people are exposed to.

If the lowest voltage we used was 230 you would see the figures for 230 volt shocks skyrocket.

Valid points.

As I said, It was just a thought to posit for discussion.

Think of all the energy we would save with 230volts.

Electric shock will will stay the same just at the higher votage and with the higher voltage it would scare off more home owners and "HANDYMEN" from doing their own electrical work and in the long run the electric shock numbers will go down .
and its a good way to get people to buy new stuff and rewire their houses.:grin:

 

[jumper]

Think of all the energy we would save with 230volts.

Hmmm, I thought a watt was a watt.

Higher voltage equals less amperage, yet if the PF is the same, I think a watt is a watt.

V x A = VA
V x A x PF = W

no?

 

[dreamsville]

Map

Map

Interesting map.

http://en.wikipedia.org/wiki/File:WorldMap_Voltage&Frequency.png

 

[brantmacga]

Just wondering. I see some previous posts about books on the history of the electrical industries evolution. Why or how did we come to use 240/120v as the standard for single phase voltages in this country?

Different from a lot of other countries. Was there much experimentation with this or did Edison or somebody just come up with it and it stuck?

Just sitting around contemplating this Saturday morning

It was orginally the 11th Commandment, but moses, having no idea what it meant, thought it was a typo and scratched it from the list.

it was unearthed some 100+ years ago by a group of gypsies when they discovered the Ark of the Covenant, thinking it was simply a nice box they could smuggle stolen children in.

Having no need for the tablets, since they didn't work well as a tambourine, they sold them at a serbian flea market. the old lady gives them to her son, yadda yadda and a few unimportant details, and today we have 120/240.


its as good an answer as any i suppose.

 

[R Bob]

I'm from UK and the general perception here is that your various different LV distribution voltages are more complex than need be.
Here we have just 400V 3-phase and 230V single phase (which is the line to neutral derived from the 400V 3-phase).
Almost all residences have just one voltage entering the premises - 230Vac, all domestic appliances are 230V including lighting, heating, washing machines etc.
No centre-tapped, no high leg, etc.

I have a colleague from the UK who is absolutely convinced that we Americans intentionally designed everything to operate opposite the way it it does in the UK just to spite the English.

Steering wheel on right, drive on right side of road, switch up=off, switch down=on, etc.

There might be something to what he says!

 

[mivey]

Hmmm, I thought a watt was a watt.

Higher voltage equals less amperage, yet if the PF is the same, I think a watt is a watt.

V x A = VA
V x A x PF = W

no?

In general: Higher voltage = less current = less delivery loss, Lower voltage = less insulation = cheaper equipment. The watt at the end is a watt, but the watt loss from source to load is what makes a higher voltage more desirable.

 

[mivey]

I have a colleague from the UK who is absolutely convinced that we Americans intentionally designed everything to operate opposite the way it it does in the UK just to spite the English.

Steering wheel on right, drive on right side of road, switch up=off, switch down=on, etc.

There might be something to what he says!

Up until now, that was a well kept secret.

 

[mivey]

In general: Higher voltage = less current = less delivery loss, Lower voltage = less insulation = cheaper equipment. The watt at the end is a watt, but the watt loss from source to load is what makes a higher voltage more desirable.

add: Lower voltage = smaller equipment = cheaper equipment

 

[gar]

100904-2029 EST

I conjecture a logical reason for the about 120 V level was that as Edison invented his electrical distribution system he wanted to make the voltage as high as reasonable to reduce copper losses. It is documented that he understood that a parallel distribution was required, and that it could not be a low voltage system because of the cost of copper. If you work in the direction of a high voltage, and the major goal at that time was lighting, then it seems that the characteristics of a practical light bulb at that time, 1879, becomes the controlling element in terms of setting the maximum usable voltage.

It seems that at some point it was realized that if you had two hot wires and a grounded neutral that again there was the possibility of a reduction in the required copper. This meant two different DC phases. One plus and one minus relative to neutral.

.

 

[esobocinski]

When I was studying Electrical Engineering, I was told that the US uses 120 volts because it was first to electrify. We had the first electrical systems in the 1870's/1880's and had the first large-scale electrification starting in the early 1890's, back when light bulbs had only carbon filaments. Apparently, carbon filaments worked best near 100 volts, but utilities picked slightly higher supply voltages like 110 and 120 to compensate for voltage drop. They reduced copper costs by using the hot-neutral-hot split-phase scheme we still use in residential, but most appliances were invented after lighting and so were designed to plug into lighting sockets that people already had installed, and thus to use lighting voltage and not to use the full voltage.

Europe however got started on large-scale electrification later, starting in the early 1900's. Europe (mostly Germany - Siemens et al) got started by using our electrical utility equipment and standards, but by then light bulbs used metal filaments and 220-240 volt bulbs were available. Using those, they could save more copper by running only two wires instead of three, ignoring the center tap and grounding one of the other wires instead. Appliances were built accordingly. The US, meanwhile, was already standardized on lower voltages. Other countries tended to adopt either the standard of their colonial overlord who forced it on them or the standard of their neighbors so that they could share power.

I don't know how true this is, but it has always made sense to me.