Finally passed my IEM exam last week after 8 weeks of studying. I was putting in about 90 minutes a day on weeknights and longer sessions on Saturdays. Scored 74% on my first practice test and got it up to 83% by test day, which turned out to be enough.
The AC/DC motor controls section was the part I kept getting wrong early on. Specifically the ladder logic diagrams and PLC troubleshooting scenarios - they're not intuitive if you've been doing mostly relay-based work in the field. I'd say that section alone accounted for about 20% of the exam.
Power factor correction and harmonic distortion questions also showed up more than I anticipated. The math isn't hard but the way the problems are worded can trip you up if you're reading too fast. I made a lot of silly errors on those until I slowed down.
What helped most was finding real troubleshooting scenarios online and walking through them step by step. Reading NEC articles related to industrial installations also filled in gaps I didn't know I had.
Passed mine with 78% after 10 weeks. The NEC industrial sections caught me off guard - I'd focused too much on the theoretical and not enough on code compliance questions.
The motor controls section is no joke. I'd strongly recommend going through real wiring diagrams if you can find them, not just textbook examples. The exam uses real-world scenarios.
PLC ladder logic was the hardest part for me too. I spent an extra 2 weeks just on that section and it was worth it - probably 6 or 7 questions on my actual exam came from PLC diagnostics alone.
Did anyone else think the harmonic distortion math was harder than it looked? I got those problems right in practice but blanked on two of them during the actual exam.
Failed my first attempt back in March and honestly electrical systems/circuit analysis was what got me. I thought I understood it but the actual test questions were way more application-based than I expected. What I changed the second time was grinding free iem electrical systems circuit analysis practice questions specifically until I could do them without hesitating. It's a different skill than just reading the material.
The other thing I'd say is don't skip AC/DC motor controls even if it feels tedious. I underestimated it both times honestly, but the second time I at least knew what to expect so I could manage my time better. You've got this if you're already putting in the hours.
I almost quit around week five, not gonna lie. The troubleshooting scenarios were killing me and I kept second-guessing every answer. What got me through was just accepting I wasn't going to understand everything perfectly and focusing on the patterns in the questions instead.
Motor controls tripped me up too. It's one of those things where you think you get it and then you see it phrased slightly differently and your brain goes blank. I drilled that section probably three times more than anything else. Honestly if you're feeling stuck, you're probably closer than you think -- the fact that you're still showing up means you're gonna get there.
Failed my first attempt and honestly the motor controls section is what got me too. I wasn't treating it seriously enough -- I thought I could just memorize formulas and call it a day, but the way they phrase the questions on the actual exam is way different from what I expected. Second time around I focused way more on understanding why the circuits work the way they do, not just what the answers are.
The other thing that changed for me was timing. I'd been rushing through practice tests to "finish" them, but that's not how I learned anything. Slowing down and actually reviewing every wrong answer -- even the ones I got right by guessing -- made a huge difference. If you're on your first attempt, don't skip that review step. It's tedious but it's where the real studying happens.