FOLLOWUP: What caused Saturday’s vault fire, outage in West Seattle

smokingmanholes
(Saturday photo, by Matt)

As promised, we followed up with Seattle City Light today about Saturday’s underground-electrical-vault problem that took out power for almost 4,000 homes and businesses. It happened right outside Spruce/LA Fitness at 39th SW/Fauntleroy Way/SW Alaska shortly after 1 pm; people reported hearing explosions, and then – as shown in the top photo – smoke began pouring out of the vault covers in the street. Some WSB commenters noted that there had been a “planned” outage in the area the night before, and in his response to our inquiry, City Light spokesperson Scott Thomsen confirmed a connection:

The underlying cause of the vault fire and outage was the failure of a piece of equipment called a j-box, which is essentially a high-voltage power strip.

The planned outage [Friday night] allowed our crews to install new equipment, including cable, which was spliced into an old cable. After it was energized, the j-box connected to the section of old cable is what failed. The crew isolated the damage and made repairs.

Seattle Fire’s time on scene was relatively short – all but one unit was cleared within less than an hour; we checked today with SFD spokesperson Lt. Harold Webb, who explained, “City Light was on scene when we arrived and quickly secured the vault and did not require further SFD standby.” But effects of the outage kept them busy, he added: “We had numerous elevator removals [in the area] due to widespread power outages.” No one was hurt. The last 130+ customers without power didn’t get it back, as noted in our updates, for almost eight hours.

6 Replies to "FOLLOWUP: What caused Saturday's vault fire, outage in West Seattle"

  • T December 12, 2016 (11:15 pm)

    Did a man hole cover really blow off?

    • Westgirl December 12, 2016 (11:18 pm)

      Yep! I was standing right at the crosswalk when it happened. Both manhole covers blew up in the air about a foot (maybe more) three times!

    • Nanner December 15, 2016 (6:21 pm)

      As a former SCL employee, I can tell you that covers do indeed blow off the vaults.  Fortunately it is a rare occurrence in our system.  The best non-gender reference to a man hole cover I know is Maintenance Hatch cover.  One advantage to the term is that it abbreviates to MHC or MH just as the traditional male term does.  This lets engineering drawings and documents stay current without tedious revisions.

  • dsa December 13, 2016 (12:13 am)

    Access cover :)

    • Azimuth December 13, 2016 (9:53 am)

      Personhole :)

  • mark47n December 13, 2016 (12:18 am)

    Lots of energy being released in a medium voltage/high voltage arc. We use it to melt 100t of steel and it can blow steel and scrap rather far if the charge is wet. You bet it could blow off a manhole cover! Maybe not into the air like Looney Toons but certainly unseat it.

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