I'm using a Fronius Primo 15 kW inverter that is a true three-phase 208/120 inverter, three hots and a neutral. I have a document from Fronius that says their inverters only use the neutral for voltage and phase detection and therefore you can apply the provisions of 705.95(B) and use a neutral conductor sized no smaller than the equipment grounding conductor.
My question is since this neutral conductor is only used for voltage and phase detection can I also apply 310.15(B)(5) which says that "A neutral conductor that carries only the unbalanced current from other conductors of the same circuit shall not be required to be counted when applying the provisions of 310.15(B)(3)(a)" (adjustments for total number of current carrying conductors).
I'm trying to run my inverter output conductors through an existing piece of 1" RMC that already has (6) #12 conductors. If I count the neutral conductor as a current carrying conductor this would be ten conductors in a raceway for a 0.5 adjustment factor and therefore I would have to upsize the Inverter output conductors to a #4 which won't fit in the 1" RMC raceway with the (6) #12 conductors (over max fill allowance). The #12 wires are for three lighting and outlet circuits on 15 A breakers so these would still be
If I avoid counting the neutral conductor when applying adjustments in Table 310.15(B)(3)(a) this brings the adjustment factor up to a 0.7 factor and I my #6 wire for my inverter output calcs out and everything is hunky dory. Also, the (6) #12 wires are for three lighting and outlet circuits each on 15 A breakers so these would still be protected with the new adjustment factor for adding the inverter circuit to the raceway.
I feel like 310.15(B)(5) seems mostly clear that I do NOT need to count this neutral in my conductor bundling adjustments. The neutral conductor only carries the unbalanced current from other conductors of the same circuit so it meets the requirements 310.15(B)(5)(a). Its a true three phase output (three lines and a neutral) so 310.15(B)(5)(b) doesn't apply.
The requirements of 310.15(B)(5)(c) is what I'm not totally clear on but I'm pretty sure inverter outputs are linear outputs (not Non-linear) and there shouldn't be any harmonic currents in the neutral.
Can anyone tell me if I have to count my neutral conductor as a current carrying conductor for my conductor bundling adjustments per 310.15(B)(3)(a)?
My question is since this neutral conductor is only used for voltage and phase detection can I also apply 310.15(B)(5) which says that "A neutral conductor that carries only the unbalanced current from other conductors of the same circuit shall not be required to be counted when applying the provisions of 310.15(B)(3)(a)" (adjustments for total number of current carrying conductors).
I'm trying to run my inverter output conductors through an existing piece of 1" RMC that already has (6) #12 conductors. If I count the neutral conductor as a current carrying conductor this would be ten conductors in a raceway for a 0.5 adjustment factor and therefore I would have to upsize the Inverter output conductors to a #4 which won't fit in the 1" RMC raceway with the (6) #12 conductors (over max fill allowance). The #12 wires are for three lighting and outlet circuits on 15 A breakers so these would still be
If I avoid counting the neutral conductor when applying adjustments in Table 310.15(B)(3)(a) this brings the adjustment factor up to a 0.7 factor and I my #6 wire for my inverter output calcs out and everything is hunky dory. Also, the (6) #12 wires are for three lighting and outlet circuits each on 15 A breakers so these would still be protected with the new adjustment factor for adding the inverter circuit to the raceway.
I feel like 310.15(B)(5) seems mostly clear that I do NOT need to count this neutral in my conductor bundling adjustments. The neutral conductor only carries the unbalanced current from other conductors of the same circuit so it meets the requirements 310.15(B)(5)(a). Its a true three phase output (three lines and a neutral) so 310.15(B)(5)(b) doesn't apply.
The requirements of 310.15(B)(5)(c) is what I'm not totally clear on but I'm pretty sure inverter outputs are linear outputs (not Non-linear) and there shouldn't be any harmonic currents in the neutral.
Can anyone tell me if I have to count my neutral conductor as a current carrying conductor for my conductor bundling adjustments per 310.15(B)(3)(a)?