Multiple wires at a bus bar screw

Does anyone know the history of Neutrals and Grounds sharing a screw at the main panel bus bar. Was there a time when it was allowed? What year did the standard become one neutral per screw? Thanks, Buck

I am not sure if this is what you are questioning but check out this thread.http://www.nachi.org/forum/f19/neutral-and-gound-under-same-lug-36898/

Congrats on your first post. Welcome!!

Thanks, I took a peek at the thread. My question is more of a historical one. Was it ever allowed or normal to combine wires under a screw? If so, does anyone know when the code changed. I am seeing some very clean panels that have shared wires under one screw, they look like an electrician did the work. The last one was a 1962 home? Thanks, Buck