Wiring RCBOs inside panel

Designmen90 · Jan 7, 2023

Hello everyone,
I would be happy to hear your opinion about wiring RCBO inside switchboboards, panels. Here I attached some example.
We have 9 (F1-F9) RCBOs, each 20A. If we connect first one (F1) with 16mm2 wire to first phase busbar, second (F2) with 16mm2 to second phase busbar and third (F3) with 16mm2 to third busbar, and neutral with 16mm2 to F1:N, then we can connect everything with comb busbar (L1/N/L2/N/L3/N/L1/N...). Because first phase wire (16mm2) will be enough to supply all first phase RCBOs (F1,F4,F7), 3x20A=60A which is OK for 16A wire. But, what is with neutral wire? The neutral wire in such situation will be undersized? Neutral is the same for
all RCBOs (9 total)....In such way, It looks that we can connect only 3 RCBOs with one comb busbar, because 3X20A is 60A for neutral wire...I would like to hear your opinion..

[ElectriciansForums.net] Wiring RCBOs inside panel

Eddy Currents · Jan 7, 2023

Neutral current is a 3 phase system are not calculated as you think depending on how balanced the loads are across each phase

I'm sure someone here will give a more detailed explanation but in the meantime check out this video which shows you an example waveform and the affects of each phase on the neutral current

westward10 · Jan 7, 2023

The neutral conductor should be of the same csa of the line conductors which supply the busbar.

Designmen90 · Jan 8, 2023

Eddy Currents said:
Neutral current is a 3 phase system are not calculated as you think depending on how balanced the loads are across each phase

I'm sure someone here will give a more detailed explanation but in the meantime check out this video which shows you an example waveform and the affects of each phase on the neutral current

Thank you, it helps a lot, I also watched the unbalanced neutral and it gives me the answer. Tnx.