So I had so many electricians working for me I took some college electrical courses in self defense. I mean there is only so many times they can look at you and explain the inverted magnetic shunt flux field right? My arch nemesis was the Wheatstone bridge! I have never used it in thirty years but instructor told us repeatedly it was the building block of industry. Moron, he hated 4-20ma loop and told us it was to complex and never used. I have used it every single day since. Instructor was out of touch with modern industry, but I still learned a lot from him. The knowledge gained was invaluable to me.