It’s relatively common in low voltage industrial controls to physically separate power distribution from control equipment, whether it’s via separate cubicles or just physical separation (known as segregation).
Let’s have a look at why this is done (with a focus on relatively small Form 1 control panels), and also some disadvantages.
Safety
This is the number one reason why distribution is segregated. Particularly if the board design includes a dedicated section for extra low voltage control, a non-electrically trained person such as a PLC programmer or integrator can access the PLC and control components with no risk of exposure to dangerous voltages.
Lower risk of accidental damage
Keeping low voltage (415/240V) and extra low voltage (12/24V) separate from each other adds an extra layer of idiot-proofing: there’s a much lower risk of an incompetent person introducing a dangerous voltage into an extra low voltage circuit and damaging expensive control equipment.
Larger overall cabinet size
There are some downsides to the segregated approach too: one of the common disadvantages is the larger size of the electrical cabinet, particularly for situations where space is at a premium.
Higher cost
There’s obviously a higher cost attached to splitting your control panel into separate cubicles. Every project should be assessed on its own merits; the extra cost and panel size is often not justified for smaller installations.
A professionally designed and well built board with low voltage and extra low voltage physically separated in the same cubicle, and with all low voltage components shrouded to be touch safe, presents minimal risk of accidental damage or injury.