why do we have 110v and 240v power supplies?

[scottand1]

whats the deal with these voltages, which one is best to use, advantages and disadvantages. Im looking to buy a new jigsaw for homes use and dont know which one is right to use?

[Mortartube]

Firstly, which country are you in? The voltages were set long ago when various countries developed mains electricity. Whatever your local voltage is, use that as it will be the most economical and sensible if you only wish to use it at home. The lower the voltage, the higher the amperage ( the bit that kills), so for instance, if you have a 1000w light bulb on 250 volts, it draws four amps. If it was on 125 volts, it would draw 8 amps (twice the current).

[mibn2cweus]

Current is what causes power loss in wiring, the thinner the wire the greater the resistance and therefore the loss. Buy using a higher voltage, (as Mortartube explains above), less current delivers the same power. This is why power transmission lines up-step the voltage for extended distances of power delivery. Thicker wire is recommended for longer lengths to reduce resistance and power loss when voltage transformation is not practical.

The danger with using higher voltages is that this increases the potential for delivering a dangerous level of current through a given resistance; such as human skin and flesh. Higher voltages can penetrate thicker insulation and jump across larger gaps between conductors.

Using a higher voltage than a device is designed for is dangerous and destructive. Doubling the voltage also doubles the current and quadruples the power and heating for a given resistance.

When less power is required a lower (safer) voltage will not contribute to significant losses.

[MustafaTinkl]

If you are going to use your jigsaw at home now and again for DIY then 240V is quite alright. If you are in any way connected with the Construction Industry or are going to do jobs on other people's premises for money then 110V is compulsory. To obtain 110V you will have to plug a small 240/110 transformer into a 240V system, they cost about �60 new, are a might heavy, and the associated plugs and cables feeding the jigsaw are different from 240V.

[qapmoc]

Just a small point to all of you who out of touch with the present situation. The European harmonized standard supply voltage which includes the UK, is now 230vac not 240vac the standard is 230vac-6%+10% which allows it be between 216.2v and 253.0v

Yeah I know that 240vac is within that limit but the official UK voltage is now 230vac.

Complain to the EEC not me please.

[stanleyman]

230 volt and 110 volt can kill you, however if you use a transformer, this is wired with a centre tapped earth so that the maximum potential to earth is only 55 volts and much more safer if a wiring fault or moisture caused the tool or you to become live. If using 230 volt tools always plug into a residual current device (RCD) to protect yourself from prolonged contact with potential live faults.

[mibn2cweus]

The voltages existing in an electronic device should not be confussed with the voltage of the power source. A TV powered by a 12-volt battery creates in its circuits 10's of thousands of volts.