If you are taking PE - professional engineering exam theoretically it is not necessary to study all of the diverse engineering subjects to pass the exam.
PE power exam is easily cleared in the first attempt if you include effective study strategies for passing the PE exam such as following the broad approach.
The strategy has helped many engineers to pass the PE exam since the examination includes many fundamentals questions.
The second approach is as popular as the broad approach and is for "those examinees who are short of time for preparation" is to focus on subjects in which they expect most questions to be from.
However the best and the last approach involve buying an FE exam study guide and solving as many questions as possible.
For the takers of PE Electrical Power exam for the first timers it is advisable to take some form of review course.