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What's Wrong Here?

Aug 27, 2007 10:38 AM, By Joe Tedesco, NEC Columnist

Hint: A case of the bends.

The use of gray duct tape may have been a better choice here, but when the metallic part of any conduit such as LFMC is over bent this is what usually happens. Don't touch the outdoor street sign this serves when it is on because the lack of continuity, improperly seated connector, and most likely broken equipment grounding conductor may lead to an electric shock.

We can cite some of the following requirements in Art. 350 (Liquidtight Flexible Metal Conduit: Type LFMC) when analyzing this installation for Code conformance.

• 350.24 Bends — How Made: “Bends in conduit shall be so made that the conduit will not be damaged and the internal diameter of the conduit will not be effectively reduced. Bends shall be permitted to be made manually without auxiliary equipment. The radius of the curve to the centerline of any bend shall not be less than required in Table 2, Chapter 9 using the column ‘Other Bends.’''
• 350.26 Bends — Number in One Run:”There shall not be more than the equivalent of four quarter bends (360 degrees total) between pull points, for example, conduit bodies and boxes.”
• 350.60 Grounding and Bonding:”Where used to connect equipment where flexibility is required, an equipment grounding conductor shall be installed. Where flexibility is not required, LFMC shall be permitted to be used as an equipment grounding conductor when installed in accordance with 250.118(6). Where required or installed, equipment grounding conductors shall be installed in accordance with 250.134(B). Where required or installed, equipment bonding jumpers shall be installed in accordance with 250.102.”

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