Do you mind which EPCC company are you currently working with and position?

First of all, single line diagram is the most important thing to study. Do you research on all the instruments, cable, etc etc on the line list. This way, you,know where is the line going, what is does, and why izit there in the first place.

2nd of all, do not stick to electrical discipline. Try to get knowledge on other discipline as well ; mechanical, structure, and piping. By getting all the discipline together, you will have a clearer picture and and upper hand in dealing with nuisance client who try to "show off" their knowledge.

Finally, be resourceful. I reckon if you ask some experience colleagues for an answer, do counter check their answer. Sometimes, they might just BS you cos they know or someone told them. But in depth, they don't understand "why" and "how".

Do the above, you will become a better employee.