Did you have a look at the vid at#12? The figure 1667 is obtained when the protective device is a 30ma RCD, this figure could be as low as 1.6, if it was B type 6a MCB.
Have a butchers at John Wards vid, it may answer your question, I think; https://www.youtube.com/watch?v=CVxBettQpPU
Thanks for the reply Midwest, I have seen these videos before unfortunately neither of them explain the relationship between the disconnection of a protective device and the resistance between an exposed conductive part and an extraneous conductive part,
Unless Iam missing the obvious! (Quite possible)
The 1.6 ohms comes from R = 50v/30a = 1.667ohms I guess?
How would a live conductor supplied by this 6a MCB come into contact with the Extraneous conductive part (that we have measured) in order to cause this voltage limited disconnection?