@Lucien Nunes raises an interesting point.
Many production lines are more than just an item plugged in.
Often a large supply feeds an isolator, from there it supplies a large control panel.
More often than not, the protective device for the main supply is far too big to provide fault protection for most of the equipment on the production line.
Main control panel will often have rows of circuit breakers, connected to bus bars for separating the supply into multiple smaller circuits.
This arrangement could be compared to any other distribution board in terms of the protection it provides to all the circuits that it feeds.
Do we consider this to be a distribution board in terms of the fixed wiring?
In general no, we don’t for the following reasons.
The production line is likely to have many hazards that are well above anything described in the electrical regs, each of these will have been addressed during the design, construction and commissioning of the line.
The simple approach that is generally used for dealing with faults detected by distribution boards etc is as follows. detect fault, turn off power to affected circuit as quickly as possible and always within x seconds. As a general rule this provides the highest degree of safety that can reasonably be expected.
For many production processes, the above approach can actually increase the risk by bring in extra hazards, some could be far worse than the original fault.
Work holding devices, electromagnetic clamping and lifting etc are some that spring to mind.
Others may be less obvious. cooling pumps, local ventilation, vacuum pumps etc.
For a production line, these modes of failure should have been risk assessed both individually and as part of the whole process.
Overload protection may be bypassed automatically or manually on some circuits to provide time for a backup system to start or another process to be stopped safely.
So in some ways a machine control panel is a distribution board
But they should not be considered as such from an inspection and testing point of view, specific knowledge and understanding is required before some recently qualified “inspector” sucks their teeth and says
Oh that’s dangerous, there should be and rcd on that.
In some places, by “improving the safety” you could be unwittingly signing off someone’s cause of death.
