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Joined 27 days ago
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Cake day: June 16th, 2026

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  • No problem! This is actually more in the factory level of power than it is grid. 480v is the common voltage inside plants.

    But sometimes you’ll see different voltages (like 380 and 720). 600v and below is considered low voltage, but sometimes 720 is considered low too if its feeding machinery. Everything above that is usually considered high voltage. But the mysterious medium voltage exists too, I’d call that somewhere up to like 20kV.

    The 13kV in this picture is controlled by the plant. Some equipment uses 13kV, but usually plants just get 13kV (or other distribution voltages) and distribute it themselves. It’s really fun equipment to operate, big switches that you have to put your body into, and it makes big mechanical thuds and you’ll hear the electric make and break connections before the switch dies. It sounds like bzzzTHUDmmmmmmm










  • It sounds like you all don’t have task specific job safety plans?

    Depends where I’ve worked, what the task is, and how it’s structured.

    Data center? Yes, we had quadruple redundancy. Boring job.

    Auto plant? PMs, yes. Reactive? Sometimes, but if the line was down, we weren’t getting them printed out. The maintenance training program was incredible though, trained the troubleshooting process, even the dumbest could have written a work plan for any piece of equipment. All equipment had PPE requirements and showed LO locations and procedures. For reactionary work, work plan was quick chat with everyone involved, then follow SOP for de-energization, verify de-energization. The work was done up front similar to how you’ve described, but on every team. Nothing got missed.

    100 year old steel mill? PMs and only sometimes. Fun place to work, but that job was almost 100% fire fighting. Safety culture didn’t exist, especially when private equity took over lol. Early on had an untrained maintenance guy in street clothes operate a tripped breaker rated over 90 cal, he did not look to see what caused trip. That was when I was able to create a glove and training program lol. But that plant is the biggest reason why I’m against double labels. That plant hasn’t filled my position, and when I left, very little of it got delegated. The arc flash stickers are probably the last line of defense, I don’t think the drawings have been looked at since I left. That’s common in a lot of plants I visit at my new job, unfortunately.

    I’ve had arguments with arc flash study providers over it - unfortunately this isn’t necessarily a dumb new engineer - these are well seasoned vets. And double labels in a book, or on a drawing makes sense. But when you look at plants that do less than bare minimum safety, it highlights how important those stickers are. The well trained facilities with good safety culture will have drawings to get information that’s missed on the removed label (primary side incident energy). But safety culture can go to shit overnight, turnover, etc. Sticking with 1 label per enclosure ensures that the safety you provide on those stickers will outlast your program.

    Labeling requirements per NFPA70E are nominal voltage, arc flash boundary, incident energy or PPE category*, and minimum PPE requirements. I believe that minimum PPE requirements should be carried through entire enclosure, and adding that to the book would close the transformer debate. But I think its been unaddressed for too long that they should be adding a note specifically calling out transformers and DPs.

    *this requirement is why you’ll see a PPE level listed instead of a PPE category if the incident energy is precisely calculated



  • That makes sense. I shouldn’t have bashed IR windows. The plants that mandate rigid conduit everywhere, IR windows make sense and are good. For the limited budget plants, I think IR windows on transformers are low priority. But infinite budget, IR windows are great.

    IR windows have a lot more use cases outside of transformers where I think they are more important. And everything has to do with frequency and down time availability.

    The last job I worked was a steel mill. I was in charge of all electrical distribution from utility to disconnect prior to production equipment. Because of the metal dust, we needed to vacuum out distribution equipment yearly at a minimum and NFPA70B recommended some tasks yearly for us. I left when my 2 day outage on a 3 day weekend was canceled. I consolidated the outage plan to a single day, and they still wouldn’t let me have it. Once we got a year behind, I left. I’ve been gone a year, and they still haven’t done it.

    I had the main transformers on a 5 year EOL plan because of oil samples and age. The lead time was 18 months for each, and they needed 3, lol. The EOL plan was also neglected.

    I would’ve felt more comfy with IR windows lmao but I wasn’t going to stick around to be the scape goat when the plant goes down.