20 Amp Dual Function breakers tripping. Caused by the source side.

[11bgrunt]

For forty years I have preached that a breaker trips because it saw something on the load side it didn't like. I am wrong.
This is the third time that many houses all complained of multiple breakers tripping. All residential.
The POCO found one vacuum switch on a primary voltage capacitor bank, that when it closed, it malfunctioned and sounded like it was arcing.
The DFs didn't trip every time, and the affected customers were not on the same POCO phase or even the same circuit leaving the substation.
In the past, I only saw Square D DF breakers. QO and Homeline. This time there was an Eaton Cutler Hammer panel with DF breakers tripping.
All pretty crazy.
These POCO circuits have thousands of customers. They received five calls to complain.
These are the links for the last two I reported on this forum.
https://forums.mikeholt.com/threads...-in-blocks-of-four-in-several-houses.2580324/
https://forums.mikeholt.com/threads...f-breaker-tripping-and-strobing-leds.2586609/

 

[brantmacga]

A few years ago a restaurant I built in central Florida had an issue where roughly 50 GFCI circuit breakers kept randomly tripping after the store opened. Somewhere in my post history is a long thread about it where I was brainstorming to find the problem . Multiple trips down there to meet the POCO and we finally opened up their handhole and found they’d substantially undersized their secondary taps coming down the pole and all the Polaris lugs had melted. If I remember correctly they ran 4/0 or 250 AL to meet our 400 copper on a 1200A service. They replaced their conductors and the problem went away.


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[ModbusMan]

I had that happen a couple of times as First Energy came through the neighborhood upgrading our meters. The first couple times confused me, but when they did mine and half the panel (QO) tripped out, it was like, "Ohhhh......"