I purchased this because of how it was described, but the majority of the information is not relevant for the skilled residential user. It doesn't discuss wire gauges on different amperage circuits, it doesn't include voltage drop on longer runs, and for the most part it contains formulas that will never be used by the do it yourself skilled homeowner. It wastes pages on first aid, and on common sense stuff that anyone who has worked around their home will already know. It is nicely printed and nicely bound, and there are pages for your own notes. Overall very disappointing. I'll keep it but would not recommend it.