In my opinion, an experienced electrician with a long history of work, this is the most acceptable reference book for electricians in everyday work. Its value lies in the fact that the directory contains the most valuable and significant information for the work of an electrical engineer. It contains almost any answer to complex questions related to the subject of electrics. You just get acquainted with the contents of this excellent guide and instantly realize that you have secured a positive credit at the qualification commission. I strongly advise you to always have irreplaceable helpers in your arsenal.