Nods to the linemen amongst us! Here's a quick one about a FD "service" call turned mini-class.
Got a call at the FD today for a "transformer on fire". We were coming back form another call, and were only a few blocks away.
When we arrived on location, we looked up, expecting to see the "ash can" ablaze, with that lovely
(and tasty) oil smoke, but we see...nothing. Spot an older gentleman on the curb, frantically waving and pointing.
Turns out that this guy had seen a fuse on a 12.5 KV line blow, and fire had shot out of it. Now there was no power in the area. We called the PoCo, and waited. I explained to the gentleman that it was a fuse, that the "real" problem had to be farther down the line. My boss showed up and left me with the pickup truck, and gave me "babysitting" duty since "...you're the electrician on the department".
After a while, PoCo showed up, found that a bird had crossed to ground on a xformer a few poles down - that fuse had blown, and when the system tried to "re-proof" (reset) a few moments later, the fuse by the caller's house had lit up.
The lineman went up in the bucket, and changed out the xformer fuse (snap)... then backed down the alley and discovered that the "burning" fuse (which looked intact) had actually arc welded inside the tube, so it didn't "pop".
Came up and ID'd myself to the lineman when he was done (Hmm... big red truck w/FD on it - no, told him I was a residential spark), and asked how these things worked, since the closest I get to his turf is new services.
Got into a discussion about rope / expulsion(?) fuses, and exactly how the spring loaded fuses on power poles work. He also explained the different layout of the ComEd system, their system status reporting capabilities, and how their OCP works on their lines. I'll tell you guys, watching that dude replace the fuse from the ground using a wobbly 28' fiberglass stick reminded me of a microsurgeon. AMAZING!
All in all, not a bad learning session!