National Electrical Installation Standards

Standards as High as Your Own

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Monday, August 6, 2018

Question:

We have exhaust fans on the roof of the hospital and currently have liquidtite flex connecting them to a disconnect. These fans have a lot of vibration in them causing the conductors to rub on the metal flex inside of the flex causing them to short out and burn the wire into. Is it against code for carflex be used on this application to stop these failures from happening?

Michael Essary

A

Answer:

Hey Michael thanks for your question. Liquidtight nonmetallic flexible conduit (LFNC) is allowed to be used as stated in 356.10 under the conditions provided. It must be listed and marked for outdoor use as stated in 356.10(3) if used there.

You might want to have someone see if they can determine why there is so much vibration, such as the fan blades being out of balance.

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