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Illustrated Catastrophes

Mar 1, 2008 12:00 PM, Joe Tedesco, NEC Columnist

As usual, never consider the following commentary associated with these photos as a formal interpretation of the National Electrical Code (NEC). Without criticizing anyone or any product, the following scenarios present us with serious safety questions.

All references are based on the 2008 NEC.

MISGUIDED METER INSTALLATION

Ted Robinson, P.E., a self-employed electrical consultant specializing in building inspections in Queens, N.Y., submitted these photos as an example of what not to do. “The first photo is of a new 200A service in an existing house. Although it's very hard to see, the main bonding jumper is not being used. In addition, notice the six taps on the main feeder cable and the two branch wires terminated on one 30A circuit breaker. The second photo shows the installer couldn't decide what to do with the meter pan ground jumper.”

Robinson identified a few of the many problems here. As noted in 110.14(A), “Terminals for more than one conductor and terminals used to connect aluminum shall be so identified.” In addition, 300.4 notes the requirements for protection of wires against physical damage. More specifically, 300.4(G) states: “Where raceways contain 4 AWG or larger insulated circuit conductors and these conductors enter a cabinet, box enclosure, or raceway, the conductors shall be protected by a substantial fitting providing a smoothly rounded insulating surface, unless the conductors are separated from the fitting or raceway by substantial insulating material that is securely fastened in place.

Exception: Where threaded hubs or bosses that are an integral part of a cabinet, box enclosure, or raceway provide a smoothly rounded or flared entry for conductors. Conduit bushings constructed wholly of insulating material shall not be used to secure a fitting or raceway. The insulating fitting or insulating material shall have a temperature rating not less than the insulation temperature rating of the installed conductors.”

Found a Code Violation? E-mail your photos (no cell phone images, please) to Joe Tedesco at joetedesco@comcast.net.

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