120/208 feeders- neutral counted as a CCC

[electro7]

Hi,

Does the nuetral conductor for a set of feeders on a 120/208V 3 phase Wye service originating from the MSB running to a panelboard count as a CCC?

I think not because it would be carrying only the unbalanced current according to 310.15(B)(5)(a).

Thanks!

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[infinity]

Only if the load is more than 50% harmonic. Not very likely so the answer is no but for the heck of it what is the type of loads being served?

 

[electro7]

Okay thats what I thought.

Its at a school, mini split hvac units, plugs, lights, etc. Not much in harmonic loads that I would think- except do mini splits have harmonic distortion with their electronics?

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[infinity]

Okay thats what I thought.

Its at a school, mini split hvac units, plugs, lights, etc. Not much in harmonic loads that I would think- except do mini splits have harmonic distortion with their electronics?

Given the nature of the building and its loads the neutral is not considered a CCC for derating purposes.

 

[electro7]

thanks

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[winnie]

One caution: if you are running so called 'single phase' feeders from a wye source, then the neutral _is_ a CCC.

You need all 3 hots and the neutral for the neutral to be balanced.

Jon

 

[electro7]

Yes thanks Jon. I remember seeing that on a Mike Holt and Ryan Jackson video.

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[DrSparks]

Only if the load is more than 50% harmonic. Not very likely so the answer is no but for the heck of it what is the type of loads being served?

Really depends on the facility. Think about it, all LED drivers, lighting ballasts, every electronic device. With the exception of resistive heating and motors, it's all electronic now.

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[electrofelon]

Really depends on the facility. Think about it, all LED drivers, lighting ballasts, every electronic device. With the exception of resistive heating and motors, it's all electronic now.

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But just because something is "electronic" that doesnt mean it will be highly harmonic or non linear. Pretty much everything now has PF correction and generally pretty "clean" power supplies. Its just really not an issue 99% of the time.

 

[infinity]

Really depends on the facility. Think about it, all LED drivers, lighting ballasts, every electronic device. With the exception of resistive heating and motors, it's all electronic now.

Still wouldn't matter in a new modern building. It would be extremely unlikely in a school to get above 50% harmonic loads on a panel. With modern equipment we're almost at the point where we can forget about high harmonic loads completely.