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What's Wrong Here?

Nov 19, 2009 5:41 PM, By Brian J. McPartland, NEC Consultant

Hint: Physical protection

In 334.15(B), which covers Type NM cable, the NEC states, "Cable shall be protected from physical damage where necessary by rigid metal conduit, intermediate conduit, electrical metallic tubing, Schedule 80 PVC conduit, or other approved means." Clearly, the NM cable shown here is in need of physical protection.

Another concern with this installation relates to the basic rule in the first sentence of 314.17, which says, "Conductors entering boxes, conduit bodies, or fittings shall be protected from abrasion and shall comply with 314.17(A) through (D)." Again, this installation fails to meet this requirement.

Additionally, this setup doesn't satisfy the rule put forward in the last two sentences in 314.17(B), which states, "Except as provided in 300.15(C), the wiring shall be firmly secured to the box or conduit body. Where raceway or cable is installed with metal boxes or conduit bodies, the raceway or cable shall be secured to such boxes and conduit bodies."

Last but not least, although it's somewhat hard to see, it appears as if the grounding conductor is spliced to a pigtail without a wire connector. Section 250.8(A) identifies the acceptable methods for connecting grounding and bonding conductors. This rule reads as follows: "Grounding conductors and bonding jumpers shall be connected by one the following means: (1) listed pressure connectors; (2) terminal bars; (3) pressure connectors listed as grounding and bonding equipment; (4) exothermic welding process; (5) machine screw-type fasteners that engage not less than two threads or are secured with a nut; (6) thread-forming machine screws that engage not less than two threads in the enclosure; (7) connections that are part of a listed assembly; and (8) other listed means." Simply wrapping one ground wire around another is not acceptable, because under fault conditions this type of connection is likely to come undone, which will "open" the fault-return path.