Electrical engineering is a field of engineering that generally deals with the study and application of electricity, electronics, and electromagnetism.
Mechanical engineering is the discipline that applies the principles of engineering, physics, and materials science for the design, analysis, manufacturing, and maintenance of mechanical systems. It is the branch of engineering that involves the design, production, and operation of machinery.
Safety engineering is an engineering discipline which assures that engineered systems provide acceptable levels of safety. It is strongly related to industrial engineering / systems engineering, and the subset system safety engineering.