https://plus.google.com/u/0/10096186...7 19407130044
This is one page from the binder we were given at a 3 day course, Introduction to Electromagnetic Interference and Compatibility (EMI/EMC) Best Practices" given at the University of Wisconsin last October.
Assuming a motor controller switches 40A in 1 usec in one wire arranged in a loop with radius of 1cm, a second wire 3 inches away (0.0762m) also arranged in a loop with a radius of 1cm would have a voltage of 4mV induced in it.