# Are the high voltages used in transmission lines responsible for 'arcing'. [closed]

I am just generally confused at the mechanism behind electrical arcing.

## closed as unclear what you're asking by John Rennie, Kyle Kanos, stafusa, heather, Jon CusterOct 27 '17 at 15:26

Please clarify your specific problem or add additional details to highlight exactly what you need. As it's currently written, it’s hard to tell exactly what you're asking. See the How to Ask page for help clarifying this question. If this question can be reworded to fit the rules in the help center, please edit the question.

Arcing happens when the electric field magnitude is high enough to ionize the molecules in the material. The minimum field that does this is called the dielectric strength of the material. For air, the dielectric strength is about $3\times 10^6\ {\rm V/m}$.
So, if you had two electrodes separated by air that produced a perfectly uniform field between them, you could create arcing with a $3 \times 10^6$ V difference at a distance of 1 m, or with a 3 V difference at a distance of 1 micron. In practice, arcing would occur at much lower potential difference because the field will concentrate around certain parts of the electrodes.