Almost sorry to recommend this - it is an invaluable reference for anyone in the utility business - because you can't buy a copy for any price.
Resource was produced internally at Pacific Gas and Electric Company in 1985 and the second edition debuted in 1992.
The book was produced by a team out of PG&E's Rate Department, so the preponderance of entries get right down to the business of rate setting and regulatory proceedings. However, there is also an abundance of straightforward utility business fundamentals, and the coverage of technical and engineering matters is excellent.
PG&E employees have been known to carry their copy from job to job, relinquishing them only upon retirement to up-and-coming newbies.
If you're desperate for a copy, make friends with someone at PG&E, or scour Ebay (good luck!). I've often thought that digitizing this material would be a huge service, not only for PG&E, but for the utility industry in toto.