Given that "a potential difference is introduced over the membrane, the associated electric field induces a conformational strong in the potassium channel" is required for our muscles to move, how powerful of an electric field is required to cause our muscles (including the heart) to fire irregularly?  How much stronger would it have to be to kill someone?

https://biology.stackexchange.com/a/53330/7973

https://en.wikipedia.org/wiki/Voltage-gated_ion_channel

(No, I'm not an "electrosensitive" afraid of cellphones or high-tension wires.)

Thanks