Wire size supply infeeds

[Slicc 0]

Hello,

I want to ask for a second opinion regarding sizing infeed wires and cables.

Take this case for example:

5G16 incoming supply cable (400VAC 3PH+N) to a panel which goes through a MCB and then to a potential distribution block. From there on i can feed various supplies:

1 off 30A Inverter (4mm wire)

1 off 15A Motor (1.5mm wire)

1 off 24VDC PS (2.2A) (1mm wire)

The wires from the potential distribution block to the MCP (inverter / motor) an MCCB ( PS)  do they all have to be the same size as the highest consumer? This case inverter so 4mm?

 

Thank you.

[BobLfoot 301]

I see you're from the UK so any advice I would given from US Codes while close to relevant will not be exactly accurate for your situation.  Let me make sure I am following your question.  Your 5G16 wire runs into the Line side of the MCB and you want to know what size wire to use between MCB and Distribution Block?  Now 16 mm^2 equates to 6ga and 6ga rates at 55 to 75 amps based on the temp of insulation.  Since your feeds add up to 45 Amp plus the PS24 feed, I'm going to assume that the MCB is 50A rated.    The wire between the MCB and Distribution Block needs to be able to take the full MCB Current.  There is a side note that lets you go a size smaller for short runs in panels.  So you're either using 16 mm^2 or 10 mm^2 between the MCB and the Distribution Block.

[Slicc 0]

@BobLfoot thanks for the answer however i am more interested in the wires from the Distribution Block to the MCP and MCCB of the consumers. Basically do i wire past my distribution depending on each of my consumer or the biggest consumer?