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Exploding underground duct bank |
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Thursday, 03 July 2008 |
 This started off as a normal day at a nice hotel. A few guy were installing interlocking brick near the main electrical room’s big air vent, when they heard a big bang sound and saw sparks and flame shooting out of the vent. Soon afterward, the hotel lost all power.
After digging a hole and cutting our way into the duct bank, we found the concrete was all hot and black. Almost 12 hours after the big bang, the old conductors were still hot to the touch. The duct bank contained six, 4-in. conduits with up to 750kcmil per conduit.
 Best anyone could figure was that a small nick in the wire during installation had boiled the water that was present in the conduit to the point where it melted the insulation off of the other conductors, causing one huge ground fault.
(Photo courtesy Michael Kelly of The Electrical Department Co.)
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Anthony Capkun
Electrical Business
House of Horrors
240 Edward Street
Aurora ON L4G 3S9
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