Electrical Conduit Cut During Aggressive Concrete / Masonry Penetration

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Type:  Lessons Learned

Publisher:  Brookhaven National Laboratory, Upton, NY

Published As:  Public


Topics:  Engineering, Operations, Management Systems, Construction/Project Management, Work Management/Planning, Excavation

On November 7, 2013, a Brookhaven National Laboratory contractor was making two 4-inch floor penetrations when he discovered that he had cut through an electrical conduit. On November 25, 2013, a contractor safety representative discovered that an in-floor electrical conduit had been damaged by the core drilling activities of the prior week. On January 16, 2014, while performing a permitted concrete penetration a subcontractor noticed that the drill had made contact with a metal conduit. Upon further investigation it was noted that the drill had pierced the conduit, which contained an energized 110 VAC power circuit.

Lessons Learned: It is recommended that ground penetrating radar (GPR) scanning equipments three-dimensional scanning capability be utilized for locations that produce inconclusive two-dimensional results, i.e. are suspect for potentially containing "stacked" subsurface objects or objects in close proximity to each other.

GPR scanning equipment limitations such as inability to scan close to fixed objects and on irregular surface conditions must be taken into consideration when scanning proposed penetration locations.

Areas scanned for subsurface objects during the concrete or masonry aggressive penetration process must be clearly marked to indicate areas that are not scanned.

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