225A 208/120V service cables de-rating cables requirements?

[Cartoon1]

Hello All,

I have a 208/120V, 3 phase system, rated 225A for a small sandwich shop. I provided 4/0 cables that is rated for 230A copper. The reviewer comments: wire sizes are insufficient for the electrical panel ampacity please resize to comply with NEC 310.15 (C)(1). So they want to derate feeder to 80%. Please let me know what you think about this.

Thank you,

 

[infinity]

They're assuming that the neutral is a CCC which for a sandwich shop it will never be one. They're just wrong.

 

[Rock86]

I agree with Infinity. They are wrong.

 

[infinity]

Here is the applicable code section. There is no way that this type of establishment will have a majority of the load being non-linear. Therefore the neutral does not count as a CCC and no 80% factor is required for the conductors.

310.15(B)(5)(c) On a 4-wire, 3-phase wye circuit where the major portion of the load consists of nonlinear loads, harmonic
currents are present in the neutral conductor; the neutral conductor shall therefore be considered a current-carrying conductor.

 

[Cartoon1]

Here is the applicable code section. There is no way that this type of establishment will have a majority of the load being non-linear. Therefore the neutral does not count as a CCC and no 80% factor is required for the conductors.

Agreed! Where does this come into play anyways? Even bigger restaurants like 800A 3 phase and up don't fall into it. The area where i can see this nonlinear loads are server/ups rooms and things with a lot of VFD's?

 

[infinity]

Agreed! Where does this come into play anyways? Even bigger restaurants like 800A 3 phase and up don't fall into it. The area where i can see this nonlinear loads are server/ups rooms and things with a lot of VFD's?

Server rooms maybe but in 2025 my guess is that's about it. When this was put in the code things were vastly different with power supplies and other equipment that added non-linear loads.