Why does the US use 110v and the UK use 220v?
In: Engineering
220v is less costly for power companies. More costly for individual devices as each plugged in device has to step down from 220v to needed voltage (think phone charger, radio etc). Less of an issue today with switch mode power supplies.
110v was deemed to be safer than 220v. Thomas Edison was a big proponent of 110v.
220v needs half the current as 110v to deliver the same amount of power. So wires can be thinner. This made distribution cheaper, so most other countries went with the higher voltages.
The UK is generally 240V – the same as the US (but US properties tend to split that into two lots of 120V).
The UK is in theory 230V, but that was a fudge to harmonise with the EU. Many places in the EU traditionally used 220V, so in 2003 they were harmonised to 230V but with a +10%/-6% tolerance, so devices in the EU (and UK) are required to work from 216V to 253V. This meant the countries that were 220V could keep their 220V supply, and those that were 240V could keep that.
The US is actually 240V. Power lines provide 120V to most homes… twice. Our power panels can provide either 120 or 240 to circuits: plenty of ovens, clothes dryers, heating and cooling is done on 240.
US had power first and decided to use 110v which spread to its neighbors with the same plugs.
By the time power spread to the rest of the world, better safety measures and methods, including the outlet itself, became invented/realized, and so running a higher voltage wasn’t considered as hazardous.
It’d cost North America way too much to change over for no real gain, so it didn’t.
They drink a lot of tea, and the water boils faster when you use twice the power to get it there.
[removed]
220 volts is more efficient. If the US started from scratch, we’d use it. And Europe used to use 127 volts, similar to ours.
The diffrence is the US was an earlier adopter of home appliances, things that couldn’t be converted to 220 volts. Europe fewer people had refridgerators and such early on, and the war destroyed a huge amount of buildings and electrical infrastructure, so it was possible to rebuild with the higher voltage, and introduce plugs with safety features. The experience of shocking yourself while trying to plug in a lamp reaching blindly behind the sofa doesn’t happen in Europe due to safety features like shutters, recessed design, and insulated pins.
The benefits of longer distances at higher voltages were better understood when the other countries were standardising their power systems
The USA standardised too early and settled on 120v AC.
They also then developed their standards to be backward compatible by supplying 240v to each house with a slight complication….
The winding in the roadside transformer has a centre tap which splits the 240v phase in half so they get two 120v phases and a 240v phase for high draw appliances.
I wouldnt say its better – it does require effectively twice the amount of copper around a house to carry the same amount of power, and high wattage appliances can only be used in certain dedicated 240v outlets. But it is slightly more safer. Outlets typically handle up to 1.5kw.
Where as on the 230v system, its more efficient with less copper needed to distribute the same number of watts around a house, and any outlet is a high wattage outlet capable of up to 2.2kw.
Latest Answers