Good day 29-03-24
3 phase installation, 9 MultiPlus II 48/500’s, 3/phase, neutral wire question, as most of the load on the system will be 220V single phase with some 380V 3 phase machinery (motors mainly)
Each of the 3 per phase +v’s are connected to a individual terminal on the 4P isolation breaker rated to suit the inverter @25 amps?? 6mm² house wire the outputs thereof are then bridged to form a common i.e. “L1 Red” of the three phases 10 or 16mm² to the main DB.
The neutrals, 6mm² house wire, are all grouped and go through the Neutral of the four-pole isolator again to one 10 or 16mm² conductor on the opposite switch terminal.
My understanding is that I have got three times 25 amps of power going through the neutral if it is used in a single-phase load condition i.e. the breaker is underrated by 50 amps it and the wiring or conduct a size should be equally able to the 75 amps.
Thus a 100A 4P breaker and the Neutral conductor as well as the positive conductor as stated above, should be equated to the 75A SANS “in South Africa that would be 16mm² house wire”
Please advise/correct my single-phase thinking
Yours
Patrick