240 volts v 110 volts

[kentishbear]

Why does Britain use 240 volts whilst most of the other countries i know use 110 volts?

Could Britain become twice as energy efficient if we halved the power output to run all our electrical appliances and therefore reduce pollution and help slow the depletion of the ozone layer?

or doesnt it work that way ?  so thats why we dont do it

[hertz]

Pinotage - the voltage levels are not actively being reduced - all that has changed is the electricity supply companies' declaration of the limits of the supply voltage. There is only a slight difference (in the lower limit) between 240 plus or minus 6% and 230 plus 10% minus 6%. As a former Electricity Supply Distribution Engineer I often used to have to try and convince customers that we were not trying to "do" them by reducing their incoming voltage!

[SexySally]

There seems to be some confusion about power and voltage as well as safety in many of the responses posted so far?

Power dissipated (in Watts) in electrical terms is defined as the supplied voltage (Volts) multiplied by the current (Amps ; symbol 'I') taken:  W = V * I

The current taken depends upon the resistance (Ohms; symbol 'R') of the device, and the voltage across it:  V = I * R

Using these two eqations, and a little basic algebra the answers to some of the questions become clearer.  What quantifies the work that we want to use everyday is the POWER.  Assuming we want it to  be constant, if you halve the voltage, you must double the current.  If you double the current, the supply wires resistance means you will double the voltage dropped along them before you get to your device.  Since the resistance of a wire depends on it's cross sectional area, you need to double the copper to get the same drop.

--- continued in part 2

[SexySally]

---- continued from part 1


If your still with me, it comes down to economics in the end.  Early domestic systems in the UK could use in excess of 1000V, but were difficult to handle(!)  Eventually, 240V was chosen as the UK standard as a compromise between ease of use and cost, while the USA and some of europe went for 100-ish systems.  Industry and expetations rose and the benefits of a higher voltage meant that europe has now standardised on 220V.  Essentially compatible with 240V in the UK but slightly overrun, whilst UK equipment in europe is slightly underrun.

Distribution networks operate at many thousand volts so that the current is corrspondingly reduced for the same power, allowing cheaper cables (less copper or aluminium) to be used, but have to be kept out of reach!

Building sites need flexible power but the chance of contact is much greater from choppping cables, etc., so it is transformed down to 110V, BUT it is also connected to earth at the centre tap of the 110V winding.  This means that unless you are most unfortunate and touch both wires at once (110V), the most shock you should get to earth is only 55V  Much safer, but needs heavier wires to carry the power.

The second part of the question asked if we could halve our power output to reduce pollution etc.  We COULD, but would you want to?  It still takes the same amount of power to do the same amount of work, to boil the kettle, to run your computer.  To halve it, you have to have less coffee, less computer time etc.  Sorry, it's not that easy unless we go back to a less power-hungry way of life.  (And if you did, would your neighbour?)

Hope you can follow it, and that it didn't ramble too much! Bye.

[phlapp]

Being an electrician I have had mains voltages up my are three times (youd have thought Id have learnt the first time!) and have never been 'thrown' anywhere! It feels like a huge buzzing in your head, and I started to get tunnel vision, I guess I was starting to pass out, I then realsied that I was being electrocuted and let go of the supply!

[rich1982]

To all that have been thrown by 230v ~ the only thing that should of happened is that your arm or body part that touched it will jump back very quick as ac (alternating current) 0-230-0-230 making the reflex in the muscle move, I am an electrician and have been electrocuted many many times at 230 volt it isn't that bad I have been got by 400 volts which only made my body jump back a few inches and I have had 11kv through my right arm which was the only one that threw me back about 5 foot, So to them that say I been thrown over the room at 230 volts have seen to many movies,

The reason why building sites use 110 is partly safe of the centre taped transformer and mostly due to the current being higher to power more powerful tools I.e.6000watt drills that pull only 4-8amps instead of 26amps at 230volt that's all,

The reason the usa use 110 volt is due to the vast space in which the current/voltage has to cover the more volts use start with I.e. the supergrid 45kv+ the more power there is there and the further it can travel with out the volt drop or the size of the cable being huge,

Take b.t. The phone wires that go under the sea between Ireland and usa the cable is 1cms per core, but the voltage unlike the normal phone ( 50volts dc) is up and near 1000 to make faster transmitting time and no lose of signal

[Richsee]

The US uses 110 volts to lessen the risk of shock. The supply is split into two 55v lines with a central earth, so if you touch one wire and your stove the 55v shock is mild. Most appliances now are double insulated and the body is isolated rather than earthed. Touching one wire and the body doesn't shock you. The 220-240 volt European standard is from the consensus of pioneer suppliers. The 50 cycle AC is from a similar consensus. One of the biggest UK pioneers (in Newcastle) used 40 cycles until the 1930s. The US 60 cycles is logical for clocks but not for movies at 24 frames per second.

[shocking]

Funny, I am in California and I just got electrocuted for the 10th time in my life (yes, I know, the dictionary says I am dead)... I can tell you FOR SURE that 110 provides a "good zing to the old ticker" (see, here is proof, I am only 41 years old and I am using phrases like "zing" and "old ticker" rather naturally, as if I were born in 1909.) It is a good thing Americans like me only have access to 100V or we all would have killed ourselves decades earlier. (Even our small children are known for sticking kitchen utensils in the sockets, it is more or less a common childhood game.)