# When to use step up and step down transformer

Well I once saw a video in which a guy made a spot welder using a step down transformer and in another video I saw someone make arcer using a step up transformer. Why using a step up to jump arcs and step down to cause heat in transmission metal

It is all about electrical power and energy. An arc need a higher voltage so that the jolt of electricity can jump over(or through) air. This is why more voltage is needed than current. And a heater needs more current than voltage. When current goes through a wire it can produce heat. The heat power is p=I^2.R More the current is there, more the conductor is hot. That is why a step down transformer is used for situations like this to increase the current.

As the power in = power out plus losses,

If you step down the voltage you get a higher current, and the output side turns are fewer with thicker wires...

If you step up the voltage, then the current goes down but the higher voltage will jump or arc...