Question 424.22.C

[tony_psuee]

I have a question regarding Article 424.22.C, overcurrent protection for subdivided heater loads. My company is looking at installing resistive heaters in cooling coils for defrost. Our product is not listed and in referencing the NEC if my heater load is greater than 48A it needs to be sub-divided, 424.22.B, and if we have a sub-divided load must provide the supplementary overcurrent protection, 424.22.C. Yet, none of our competitors provide the protection as a standard, only as an option. I have tried to get a justification and only get mumbling that ends with and that's the way it has always been done. Can anyone provide some direction on this section?

Thanks,

tony

 

[nvcape]

Re: Question 424.22.C

Why not get UL so that it is "acceptable to the authority having jurisdiction"? Also, article 424 is for space heating, and your description did not appear to be this?

 

[tony_psuee]

Re: Question 424.22.C

nvcape,

424 is for space heating, however 440.3.B states that articles 422, 424, or 430 shall apply to equipment without hermetic compressors, which is this equipment. I use 430 for the motors so am looking at 424 for the electric heaters. Getting UL listing is not a preferred option because this is not cookie cutter equipment. There are enough design changes for each job to require UL testing every time. The panels supplied are UL but the mechanical equipment is not.

Thanks for responding,
Tony