More than a decade into my career, I still think about a specific Thursday afternoon from my first few years in the industry, long before I joined Isomer. It always starts the same way: with two little plus and minus signs on a loop sheet.
That project, at the firm where I got my start, was my first real shot at owning something from the ground up. I was the junior lead, which sounds impressive until you realize it mostly means you get to do everything and make sure everything is perfect. P&ID support, instrument spec’ing, PLC panel design, PLC programming, HMI design, and eventually start-up and commissioning in the field. I was hungry for it. I wanted to be the guy who could say he touched every piece of a project, start to finish.
By the time we got to the final five percent, I felt beyond happy to be where we were on the project, but also fully exhausted from the months of work. We’d built over 300 loop sheets tracing every signal back to the PLC. Three hundred. If you’ve never done this kind of work, understand that a loop sheet is not exciting. It’s a document that tells you exactly how a wire gets from a field instrument to a terminal in a panel, and it needs to be right, because most of the time nobody double-checks it in the field before they turn the power on. Out of those 300-plus sheets, two loops were still open. We didn’t have final terminations yet, so we put placeholder tags in place with a plus and a minus and made a note to confirm the real terminations against the vendor manual before issue.
I want to be honest about what happened next, because the honest version is embarrassing. I looked at those two loops, decided they looked right, and moved on. I didn’t go back and verify them against the manual. I was young, confident, and if I’m being fully truthful, I was a little proud — I thought I’d gotten good enough that my first pass was basically my final pass.
Here’s the thing about being early in your career: you don’t yet know the difference between confidence and correctness. They feel identical from the inside.
I had a mentor at that first firm who used to say something that, at the time, I thought was just a suggestion. He’d tell me, no matter how many hours you’ve put into a drawing, no matter how many times you’ve already looked at it, go back and back-check it before it goes to someone else. Not a fresh set of eyes. Your own eyes, one more time, slower, assuming you’re wrong until you can prove you’re not. I nodded along and, on those two loops, I skipped it. I told myself I already knew the answer; why else would I have put the terminations on the drawing?
We found out how wrong that assumption was in the field. We energized instrument control power to two flow transmitters. The problem was that the placeholder terminations I’d never gone back to verify put 120 VAC where 24 VDC was supposed to be. I watched two instruments start smoking in real time. They were done, not “let’s troubleshoot this,” just gone. We were lucky that the local vendor had replacements on the shelf, because otherwise that would have been a multi-week delay instead of an afternoon one.
What gets me, even now, is the math on it. The back-check my mentor talked about would have taken 15 minutes. Fifteen minutes against two ruined instruments, a scramble for replacements, and a start-up crew standing around while I quietly reevaluated my entire relationship with my own competence. That is not a good trade, and I made it because I was too eager to be finished to be careful.
That was the last time I ever skipped a back-check. Not because I got yelled at (nobody needed to yell; the smoke did the talking) but because I finally understood what my mentor meant. He wasn’t telling me to be slow. He was telling me that the version of you who did the work and the version of you who checks the work need to be treated as two different people, because the person who built it is the worst person possible to trust to find their own mistakes. You’re too close to it. You already believe it’s right.
I’ve carried that into every project since, at every firm I’ve worked for, including Isomer. Instrumentation, panel design, programming: it doesn’t matter. The work isn’t done when it looks right to the person who made it. It’s done when you’ve gone back, assumed you missed something, and made yourself prove otherwise. Fifteen minutes, every time. I learned that lesson from a burnt transmitter and a mentor who’d learned it from his own burnt transmitter 20 years before I started in the industry. I even back-checked this blog post before submitting it. It’s engraved in my core.
That early lesson is part of why the back-check isn’t optional on our projects at Isomer, no matter who’s doing the work or how many years they’ve got behind them. We build it into how we review drawings, and we build it into how we mentor the next generation of engineers coming up behind us — because somebody is going to hand them the same 15 minutes I skipped, and we’d rather they take it.
