It's clearly different to a situation where an overpowered FCU or MCB can power a lower powered device e.g. lights on a 32Amp breaker.
That's the parallel I was trying to draw.
There is no comparison - totally different devices. FCUs and MCBs are passive devices i.e.they are not power supplies. They are just a combination of a switch and an overload and/or fault protection device. Under normal operation they are no different from a length of cable. Their current ratings refer to the maximum current they can handle under normal operation. The actual current that flows is a function of the supply voltage and the load being supplied.
This site seems more confusing than helpful. For example, the statement: "Voltage is the difference in charge between two points."
They are not even in the same units, let alone whether they give a good picture.
The idea to help people build a picture of electricity is a good one. Many of the issues that arise on forums such as this are caused by not having that all important image in their mind.
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