A friend did some research this past spring that involved Ontario  
Hydro records. I asked him for some details.

Ontario Power Generation holds the Ontario Hydro files that he looked  
at. They (the records) used to be held in their main building on  
University Ave, but they have been relocating and culling them over  
the past decade. He had to go through an Access to Information Request  
to look at the files. After it was granted he was directed to the OPG  
facility on Kipling. It sounds like they have very few external,  
non-OPG researchers visit and records were poorly organized,  
identified, described.

I can provide you with a few more details about his visit offline. I  
don't have any information on the specifics asked about at the  
beginning of this thread.