You will nopt find this requirement in the NEC. It is a HVAC requirement. It has become a problem that this stuff is not bonded and it connot clear a short/lightning strike. It has happened to my customers nieghbor. A fire actually started from this. I spoke to a local inspector and he gave me his version of the bonding, but told me to call his office for the actual paperwork. I have not heard back as of yet. I had a HVAC guy run a #6 into my panel on another job(made a mess of my panel) the city inspector said Ok but was un fimaliar with this requirement. I have spoken to 2 other HVAC guys I know and each has a diffrent version. That is why I figured this was the place to go?
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