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What's Wrong Here? Hint: Mismatched Conductors

What's Wrong Here? Hint: Mismatched Conductors

Can you identify the Code violation(s) in this photo?


How well do you know the Code? Think you can spot violations the original installer either ignored or couldn't identify? Here's your chance to moonlight as an electrical inspector and second-guess someone else's work from the safety of your living room or office. It's your turn to identify the violation.


Hint: mismatched conductors


Find the Answer

James Hooten, a service manager with Hargis Electric, LLC in Paris, Texas, thought everyone would like to see a photo of this 20kW heating unit one of his service techs fixed not so long ago. "It has a No. 3 THHN conductor feeding one of the breakers with a No. 10 solid conductor jumper to the other breaker," says Hooten. "It was connected to a 100A ITE breaker in the panel."

I would call attention to the requirements noted in 240.4 for protection of conductors, which states: "Conductors, other than flexible cords, flexible cables, and fixture wires, shall be protected against overcurrent in accordance with their ampacities specified in 310.15, unless otherwise permitted or required in 240.4(A) through (G). We can also point to a rule in Art. 424 [Fixed Electric Space-Heating Equipment]. Section 424.9 notes, "All fixed electric space-heating equipment shall be installed in an approved manner."

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