Feeders

[Strathead]

Would you mind elaborating on how the neutrals are not considered CCCs in my case specifically if I were to run them? I think I have been trained to always consider neutrals as a CCC maybe because it's easier than arguing with the engineer but in this case I would love to win an argument lol.

Do you understand the impact of triple harmonics? Non-linear loads can cause harmonics on the neutral that actually increase the amperage on the neutral beyond the phase currents. With today's technology few of those loads exist today. I would need an engineer to determine there were non linear loads of concern to count my neutral, not the other way around. You will notice that your riser diagrams rarely have wires large than 3 CCC ampacities done by Engineers as an example to hold up.

 

[Rockinrmt]

Do you understand the impact of triple harmonics? Non-linear loads can cause harmonics on the neutral that actually increase the amperage on the neutral beyond the phase currents. With today's technology few of those loads exist today. I would need an engineer to determine there were non linear loads of concern to count my neutral, not the other way around. You will notice that your riser diagrams rarely have wires large than 3 CCC ampacities done by Engineers as an example to hold up.

The hardest part for me is telling the engineers on this project how to do their job. I am not an engineer so they are the ones that have to bless whatever I come up with since they don't wanna do the leg work. I shouldn't be doing any of this for them but they don't seem to have a clue. Figured I would ask those smarter than me who can elaborate on the specifics.

 

[infinity]

The hardest part for me is telling the engineers on this project how to do their job. I am not an engineer so they are the ones that have to bless whatever I come up with since they don't wanna do the leg work. I shouldn't be doing any of this for them but they don't seem to have a clue. Figured I would ask those smarter than me who can elaborate on the specifics.

No problem, as electricians many of us have been there. I've been on several jobs where half way through the job our shop engineer either quit or was fired and the guys in the field finished the shop design on their own.

 

[don_resqcapt19]

The reason you don't count a neutral as a current carrying conductor is because the adjustment factors are based on the I²R losses in the conductor that cause heat. The adjustment factor is to limit the heat. Since the heat is I²R we can look at it this way for a 3 phase circuit, not including non-linear circuits.
If we have circuits loaded to 20 amps and all of the loads are line to neutral we can look at the heat a number of ways
A phase current 20 amps, 400R watts of heat
B phase current 20 amps, 400R watts of heat
C phase current 20 amps, 400R watts of heat
Neutral current 0 amps, 0 watts of heat
Total heat 1200R watts of heat
A phase current 20 amps, 400R watts of heat
B phase current 20 amps, 400R watts of heat
C phase current 20 amps, 0 watts of heat
Neutral current 20 amps, 400R watts of heat
Total heat 1200R watts of heat
No matter what combination of current on the phase conductors and the neutral, the total heat will never exceed the heat created by all three phase conductors being loaded at 20 amps.