# Non contact electricity

#### Unfettered

How far realistically are we from having wireless energy for homes businesses etc? I heard a few years back I think a swede team were testing and working on this with some success but had issues with the power being able to be utilised over distance but it was supposedly safe for organic material,

I could be wrong in those details it was a while back but since that story seems to have gone cold was it a dead end with our current tech (no pun intended)

#### studiot

Here is where you need some basic Physics.

Consider a UK standard 2.5 square mm twin and earth ring main.

The max breaker for this supply is 32amps

Since power = voltage x current

This works out at 240 x 32 = 7680 watts or 7.7kW.

This corresponds to a power density of 7680/2 x 1000 x1000 watts per square metre = 3480megawatts per square metre

By comparison solar radiation has a power density of 1.4 kilowatts per square metre and TV transmitters a maximum allowable power density is 2 watts per square metre for public safety.

So if you allowed a transmittted power level of 2000 times the midday sun or 1.5 million times the safe TV transmitter level , you could replace your ring main with wireless.

Happy frying.

#### Unfettered

So ok I don't want to sound silly but couldn't they use an electro magnetic field to spread safely enough to create ac power in coils placed about the place and scale down until its far safer and localised in situ to be used safely over short distance per outlet in some way,?

I am not as knowledgeable as trying to further my understanding of the thin knowledge I possess and definitely don't want to fry lol

#### studiot

So ok I don't want to sound silly but couldn't they use an electro magnetic field to spread safely enough to create ac power in coils placed about the place and scale down until its far safer and localised in situ to be used safely over short distance per outlet in some way,?

I am not as knowledgeable as trying to further my understanding of the thin knowledge I possess and definitely don't want to fry lol
Of course you can scale it down.
There is another thread just now here at PHF about a wireless electric toothbrush charger.

But you asked to generally replace wires with wireless so I worked it out for my wife's washing machine and tumble drier which would fry the cat at the same time.