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Monday, December 11, 2023
Question:
Good morning CQD people, thanks for the opportunity to have a useful morning brainteaser with this forum. We often specify Liquid-tight Flexible Metallic Conduit (LFMC) be used in mechanical rooms and on rooftops for connections to vibrating equipment, to help with isolation. However, according to 350.12 LFMC is not suitable for use where subject to physical damage. I would consider a mechanical room a place where it
is exposed to physical damage, because the conduit is not concealed.
My question is: How could we achieve vibration isolation of equipment in a damp environment if the conduit is not concealed? Thanks in advance, Cooper
A
Answer:
Hi Cooper, thanks for the kind words and your participation in the CQD. Section 350.10 provides the uses permitted for LFMC and the charging text of this Section permits the use of LFMC in both concealed and
exposed installations, meaning simply because the LFMC is exposed does not mean it is subject to physical damage. Whether or not the LFMC is subject to physical damage is ultimately decided by the AHJ. The AHJ should base this decision on external or environmental factors that may contribute to the wiring method being damaged. This is one of those scenarios where it is always good practice to check with the AHJ if in doubt for a specific installation.